national institute of materials physics annual report 2012

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national institute of materials physics annual report 2012
NATIONAL INSTITUTE OF
MATERIALS PHYSICS
ANNUAL REPORT
2012
1
National Institute of Materials Physics
(Institutul National de Cercetare-Dezvoltare pentru Fizica Materialelor)
DIRECTORATE
Director: Dr. Lucian Pintilie
Scientific Director: Dr. Florin Vasiliu
ADDRESS
P.O. BOX MG – 7
Bucharest – Magurele / ROMANIA
Tel. (+4) 021 369 01 85
Fax (+4) 021 369 01 77
E-Mail
L. Pintilie: [email protected]
F. Vasiliu: [email protected]
WWW
http: //www.infim.ro
2
Table of Contents
Preface .............................................................................................................................................4
Laboratories ...................................................................................................................................7
Personnel .......................................................................................................................................12
List of Personnel .......................................................................................................................13
Visiting Guests ..........................................................................................................................18
Ph.D. Theses ..............................................................................................................................19
Awards.......................................................................................................................................20
Honorary Membership ............................................................................................................21
Publications and Presentations ...................................................................................................24
Books .........................................................................................................................................25
Journals .....................................................................................................................................26
Conference Proceedings ...........................................................................................................60
Contributed Presentations .......................................................................................................63
Invited Lectures ........................................................................................................................85
Selected Results ............................................................................................................................89
Condensed Matter Physics at Mesoscale ................................................................................89
Nanoscale Physics ...................................................................................................................132
Potential Applications ............................................................................................................157
Patents and Patent Requests .....................................................................................................189
Seminars......................................................................................................................................191
Events ..........................................................................................................................................196
International Cooperation.........................................................................................................212
NIMP Funding ...........................................................................................................................219
3
PREFACE
2012 was a successful year for the National Institute of Materials Physics, especially
from the point of view of the scientific output. Thus NIMP has published 180 papers in
ISI journals which is equivalent with a cumulated impact factor of 377.2, the highest in
the institute history. We must mention that in next couple of months, some other
publications will be added at this record (taking into account some delayed journal
issues) and also that now other 33 papers are already published or accepted for 2013. In
Fig. 1 it is shown the NIMP output in the last five years which prove the consolidation
of the scientific performance especially by comparison with years 2009, 2010 when the
impact factor was roughly half from the nowadays value.
Paper Number
Cumulative Impact Factor
200
400
NIMP OUTPUT 2008-2012
Paper Number
160
300
140
120
200
100
Cumulative Impact Factor
180
80
2008
2010
2012
A
Fig. 1
4
Other important observation is related to the tendency of publication in higher impact
factor journals (Fig. 2). If in the years 2009-2010, the cumulated impact factor of
journals with FI>2 was 75 and 120, respectively, in 2011 this increased to 200 and to 240
in 2012 (even without adding the two papers published in very high impact factor
journals-one of 54 in 2011 and other 36 in 2012). Therefore, about 60% from cumulated
impact factor is now obtained only from papers published in the very prestigious
journals.
NIMP Impact Factor Distribution
2008-2012
90
80
70
60
50
40
30
20
10
0
2008
2009
2010
2011
2012
0-1.0
1.0-2.0
2.0-3.0
3.0-4.0
4.0-5.0
>5.0
Fig. 2
In 2012 a number of 176 contributed presentations (invited, talk or poster) have been
selected to be communicated at international conferences, congresses or workshops.
Research work was dedicated to a high number of projects such as: 3 CORE projects, 5
projects UEFISCDI Module III, 13 IDEAS-PCE projects, 11 HUMAN RESOURCES
projects, 2 IDEAS-PCCE projects as coordinator, 2 IDEAS-PCCE projects as partner,
3 IFA-CEA projects, EURATOM 6 projects, 4 PARTNERSHIP projects as coordinator
and other 13 as partner.
NIMP continued to develop new international collaborations with research institutions
from whole word. In 2012 NIMP has continued or started 2 FP7 projects, a CERN
collaboration, 2 projects Romanian Swiss Research Program RSRP, 3 projects with
Commissariat de l”Energie Atomique (CEA), 1 project with Agence Nationale de
Recherche (ANR), other 7 European-funded projects, 6 inter-governmental agreements
and 12 bilateral cooperation with foreign institutes or universities.
Several events with international participation were organized in 2012, among which
the workshop "Advanced workshop on solar energy conversion" ( 21 - 23 May 2012.),
the 7th International Conference on Advanced Materials, ROCAM 2012, 28-31 August
5
2012, Brasov, Romania and two exploratory workshops entitled: ”Theory and
experiment in surface, interface and nanoparticle physics” and “Materials in extreme
conditions: processing, characterization and applications” in the framework of the
conference “Diaspora in Romanian Research and High Education-“Seeds for the Future
“ (25-28 September 2012)
2012 was a challenging year for NIMP. The institute has been evaluated by an
international panel who has decided that the institute will be certified for research
(certification level: A +). We think that the future institutional funding will depend
entirely on the result of this evaluation exercise.
In summary, the NIMP team is ready to face the challenges of the present in order to
consolidate the leading position of the institute in the national research system and his
excellent visibility at international level.
Dr. Lucian Pintilie
General Director
6
Laboratories
10. Laboratory of Multifunctional Materials and Structures
The laboratory is dedicated to the research of oxidic materials and nanostructures with an
emphasis on functionality and applications. A wide range of properties of the materials are
studied, including here dielectric , ferroelectric, piezoelectric, optic and transport, for bulk
materials, thin films and nanostructures.
There are two main research directions:
1. Synthesis and characterization of nano-objects (e.g. nanowires, nanotubes,
nanocylinders, nanospheres) and of devices or applications including such low
dimensional structures (e.g. nanowire diodes, photodetectors, OLED,
ultraminiaturised light emitting structures, targeted drug delivery vectors).
2. Synthesis and characterization of bulk materials and thin films with ferroelectric,
piezoelectric or multiferoic properties for applications in various fields such as
information technology, communications, microwave technology.
The activities in the laboratory are well balanced between synthesis and characterization
of materials. The main methods of preparation employed are both physical and chemical:
pulsed laser deposition and magnetron sputtering, sol-gel, electrodeposition and chemical
bath deposition, chemical synthesis and various polymerization approaches. In this way
materials with different characteristic sizes are obtained, such as bulk ceramics, thin films
and multilayers (including MOS structures), semiconductor and metal nanowires and
polymer nanofibers, simple structure or core shell nano-particles of various materials ranging
from polymers to semiconductors or magnetic oxides.
Characterization techniques cover a wide range from optical to transport properties, from
structure to microwave properties or magnetism and are basd on a high quality infrastructure.
Examples of techniques unique in the area are: deep level transient spectroscopy, near field
phtotoluminescence spectroscopy, cathodoluminescence, microwave characterization of
materials on a wide range and up to far infrared.
The structure of personnel is also well balanced, 24 physicist and 6 chemists representing
the research personnel of the laboratory out of which 11 young assistants being hired in the
last few years.
20. Laboratory of Magnetism and Superconductivity
The laboratory is devoted to research in the field of materials with magnetic or
superconducting properties and related electronic phenomena. The research process covers all
the steps from preparation (powder, bulk, ribbons, thin films or nanostructures), going
through basic physical characterizations, and ending with in-depth analysis of the magnetic
dependent and superconducting properties. The laboratory is composed by two groups of
specific activities related to electronic correlations and magnetism and respectively,
superconductivity. As main research directions are to be mentioned: size effects and
interactions in nanoparticulate systems and nanocomposites, interfacial interactions and
surface electronic/spin configurations in layered nanosystems, molecular magnets, phase
7
transitions and electron correlations in functional materials, vortex dynamics in high-Tc
superconductors, MgB2 for practical applications, composite superconductors, exotic
superconductors (iron-based pnictides, non-centro-symmetric superconductors). The
presently available experimental facilities allow the complex processing and investigation of
the mentioned systems as well as the understanding the basic interaction mechanisms at the
microscopic level, by using first principles atomistic modeling and simulation of materials
within the Density Functional Theory (DFT) framework, on specially assigned computer
clusters.
The magnetic and superconducting structures are prepared by various technologies,
like mechanical attrition, melt spinning, microwave annealing, spark plasma & hot press
sintering, radiofrequency sputtering, chemical routes, etc. Subsequent processing via thermal
treatments (assisted or not by applied magnetic fields) or via gas reaction control can be also
managed.
The structural and morphological characterization of the samples and a large field of
magnetic, thermodynamic and transport properties are studied by Physical Properties and
Magnetic Properties Measurement systems (PPMS, MPMS-SQUID), Vibrating Sample and
Magneto-Optic Kerr effect magnetometry (VSM and MOKE), DSC/DTA as well as Laser
Flash Calorimetry. The declared purpose of understanding and controlling the electronic
phenomena and spin configurations is enhanced by the whole range of Mössbauer
spectroscopies (the only institute in Romania), from temperature /field dependent Mossbauer
spectroscopy, to the surface/ interface sensitive Conversion Electron Mössbauer
Spectroscopy (CEMS).
Spark Plasma Sintering (left), MPMS (middle) and PPMS (right) systems
30. Laboratory of Nanoscale Condensed Matter
There are 3 reseach groups in the laboratory of Nanoscale Condensed Matter Physics:
SITSC-XESD team ( Surfaces, interfaces, thin films and single crystals. X-ray / electron
spectroscopies and diffraction), Si- and Ge –based nanomaterials and Nanostructures team
and the Theoretical Physics group.
The main activities of the SITSC-XESD group are centred on the development and
complex studies of new materials, heterostructures, surfaces and interfaces. The group
utilizes and maintains several widely used installations of NIMP: (i) a surface and interface
science cluster composed by a molecular beam epitaxy (MBE), a scanning tunneling
microscopy (STM) and a spin- and angle-resolved photoelectron spectroscopy (SARPES). A
non-negligible amount of activity is dedicated to the development of analysis methods,
starting from the theory of quantitative assessment to the adjustment of the experimental
8
conditions. The group also provides unique expertise at national level in two very demanded
fields: X-ray diffraction and X-ray photoelectron spectroscopy. Also, this is practically the
unique group in the country concentrated on surface and interface science, working in real
ultrahigh vacuum (UHV, 10-10 to 10-11 mbar). An MBE setup is installed and works
currently.
The X-ray diffraction expertise is also boosted by novel developments in the XRD
basic theory and data analysis, often implemented in widely used XRD analysis codes, which
emerged also from the SITSC-XESD group.
The Si- and Ge –based nanomaterials team is working in the field of nanostructured
semiconductors with applications in nanoelectronics, photovoltaics and sensors. The group
studies:
• Films of Si nanodots embedded in amorphous SiO2 matrix: (i) preparation; (ii)
investigation of microstructure, electrical transport, phototransport, and
photoluminescence with the aim of capturing quantum confinement effects; (iii)
modelling of nanoparticle energy structure.
• GeSiO-based nanostructures: (i) preparation of Ge nanoparticles embedded in a-SiO2
matrix, by magnetron sputtering and sol-gel methods; (ii) investigation of electrical
behaviour and phototransport (experiment and modelling), photoluminescence and
Hall effect.
• Electrical processes in carbon nanotubes based structures.
• Percolation phenomena: evidenced in carbon nanotubes based structures, Si nanodots
embedded in amorphous SiO2 matrix and nanocrystalline porous Si.
• Trapping phenomena in Si-based nanostructures: stress-induced traps.
• The Theoretical Physics Group studies quantum transport phenomena in mesoscopic
systems and provides phenomenological models and reliable descriptions of various
effects observed in transport measurements.The main research topics cover several
timely and challenging issues of mesoscopic transport: the transient transport regime
in nano-devices, the mesoscopic Kondo and Fano-Kondo effects, controlled and
intrinsic dephasing in mesoscopic interferometers, Coulomb drag and quantum ratchet
effects in parallel quantum dots, spin interference in Rashba rings.
40. Laboratory of Optical Process in Nanostructured Materials
The research activity in this laboratory is focused on the study and characterization by
optical methods of the nanocomposites and nanostructured materials. Other research topics
regard the preparation and characterization of semiconducting nanometric structures, of
electrochemical synthesis of polymers with special properties as well as the synthesis and
characterization of calcogenide glasses.
The main equipment’s used to optical characterization of investigated materials are:
UV-VIS-NIR spectrometer (Lamda 950 model, Perkin Elmer), FTIR spectrophotometer
(Vertex 70, Bruker), FTIR imaging microscope (Perkin Elmer), FTRaman spectrometer
(RFS 100/S model, Bruker), confocal Raman spectrometer (T64000 model, Horiba Jobin
Yvon) equipped with Ar and Kr lasers, Scanning Near-Field Optical Microscope and Atomic
Force Microscope (Nanonics), a fluorolog (3.2.2.1 model, Horiba Jobin Yvon),
thermoluminescence reader (TLD 3500 model, Harshaw), experimental setup for
photoconductivity studies and solar simulator (LOT Oriel). Other equipment used to
characterization and/or preparation of materials are: broadband dielectric spectroscopy
9
system (Novocontrol), drop shape analysis (DSA 100 model, Kruss), the film evaporation
system for organic materials research “Spectros”, Langmuir –Blodgett systems (KSV 5000
model), spin coater (KW-4A model, Chemat) and a potentiostat/galvanostat (Voltalab 80
model, Radiometer Analytical). The main applications reported by this laboratory are in the
field of the non-linear optic (as shown in Fig. 1), superhydrophobic textiles, the sensors,
batteries and supercapacitors as well as energy conversion (dye-sensitized solar cells).
Fig.1 Anomalous anti-Stokes Raman emission at λexc=514.5 nm of LiNbO3 in three morphological forms: (a)
single crystal, (b) platelet made from LiNbO3 powder compressed no hydrostatically at 0.58GPa and (c)
micrometric (<40 µm) LiNbO3 powder. On the right side are shown the optical microscopic images of the laser
spot focused on the respective samples. Small green circle indicates the diameter of the laser spot.
50. Laboratory of Atomic Structures and Defects in Advanced Materials
This laboratory is mainly committed to structural investigations by advanced
characterization methods such as analytical transmission electron microscopy (TEM),
electron paramagnetic resonance (EPR), Mössbauer spectroscopy. The research activity
includes, also, synthesis of nanostructured materials by the hydrothermal or co-precipitation
methods. Other important research subjects are related to the gas sensing and photocatalysis
fields.
Among the important research equipments we mention: two analytical transmission
electron microscopes, a SEM-FIB dual analytical system, five EPR spectrometers operating
in several microwave bands and working modes down to liquid He temperature, three
Mössbauer spectrometers, XRD installations, complex gas mixing station for electrical
measurements under controlled gas atmosphere for gas sensing, specialized equipments for
hydrothermal and co-precipitation synthesis.
A new atomic resolution TEM has been installed in 2011. The instrument is provided with
probe Cs corrector of the spherical aberration, EDS and EELS microanalytical facilities.
Another newly acquired equipment is the analytical SEM-FIB dual system which has been
installed in a cleanroom next to equipments for photolithography and nanolithography.
10
(a)
(b)
Figure 2. (a) The atomic resolution TEM, JEM ARM 200F, recently installed at NIMP; (b) HAADF-STEM
image of the SrRuO3-SrTiO3 interface obtained with the JEM ARM 200F microscope installed at NIMP.
The research activity of the scientists working in this laboratory is focused on the
physical properties of advanced materials (structure, optical, electrical properties), resulting
either as size effects (nanostructures, thin films) or by structural defect engineering. The
scientific concerns are mainly directed towards the discovery, investigation and manipulation
of physical properties at nanometric and atomic scale for the development and
characterization of new materials (dielectrics, semiconductors, alloys, ceramics) to be used in
various applications (semiconductor technology, gas sensing, radiation detectors,
telecommunications).
11
PERSONNEL
12
List of Personnel
Lab. 10
Laboratory of Multifunctional Materials and Structures
HEAD:
Dr. Ionut ENCULESCU
E-mail: [email protected]
Tel.: (+4) 021 369 01 85
Fax: (+4) 021 369 01 77
1. Dr.Ioana PINTILIE
2. Dr.Cornel MICLEA
3. Dr.Andrei IOACHIM
4. Dr.Gabriel BANCIU
5. Dr.Daniela PREDOI
6. Dr.Corneliu Florin MICLEA
7. Dr.Marin CERNEA
8. Dr.Monica ENCULESCU
9. Dr.Silviu POLOSAN
10. Dr.Luminita AMARANDE
11. Dr.Nicoleta PREDA
12. Dr.Viorica STANCU
13. Dr.Liviu NEDELCU
14. Dr.Aurelian GALCA
15. Dr.Alin IUGA
16. Dr.Lucian Dragos FILIP
17. Dr.Elena MATEI
18. Lucian TRUPINA
19. Cristina BUSUIOC
20. Carmen CIOBANU
21. Cristina DRAGOI
22. Andrei FILIMON
23. Camelia FLORICA
24. Irina GHITA
25. Georgia IBANESCU
26. Simona ICONARU
27. Roxana RADU
28. Corina RADU
29. Liliana TRANCA
30. Marian IOSIF
31. Alexandru GAVRILA
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher II
senior researcher II
senior researcher II
senior researcher II
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
engineer
engineer
13
Lab. 20
Laboratory of Magnetism and Superconductivity
HEAD:
Dr. Victor Eugen KUNCSER
E-mail: [email protected]
Tel.: (+4) 021 369 01 77
Fax: (+4) 021 369 01 77
1. Dr. Mihaela VALEANU
2. Dr. Neculai PLUGARU
3. Dr. Andrei GALATANU
4. Dr. Lucica MIU
5. Dr. Petre BADICA
6. Dr. Gheorghe Virgil ALDICA
7. Dr. Viorel Constantin SANDU
8. Dr. Ovidiu CRISAN
9. Dr. Petru PALADE
10. Dr. Valentina MIHALACHE
11. Dr. Alina CRISAN
12. Dr. Felicia TOLEA
13. Dr. Carmen PLAPCIANU
14. Dr. Maria-Cristina BARTHA (Valsangiacom)
15. Gabriel SCHINTEIE
16. Ion IVAN
17. Bogdan POPESCU
18. Mihaela SOFRONIE
19. Ancuta BARSAN
20. Simona Gabriela SANDU
21. Magda GALATANU
22. Aurel LECA
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher III
senior researcher III
senior researcher III
researcher
researcher
researcher
researcher
researcher
researcher
researcher
assistant researcher
assistant researcher
assistant researcher
engineer
23. Dr. Adrian Ioan CRISAN 1
24. Dr. Adrian JIANU 2
25. Dr. Marilena TOMUT 3
senior researcher I
senior researcher I
senior researcher III
26. Dr. George FILOTI
senior researcher I
(associate collaborator)
27. Mihai Burduselu
assistant researcher (collaborator)
Univ. Birmingham, Dept. Met & Mat., Birmingham, England.
Institute for Pulsed Power and Microwave Technology, Forschungszentrum Karlsruhe.
3
GSI / KP2 Nuclear Structure and Nuclear Chemistry, Darmstadt.
1
2
14
Lab. 30
Laboratory of Nanoscale Condensed Matter
HEAD:
Dr. Valeriu MOLDOVEANU
E-mail: [email protected]
Tel.: (+4) 021 369 01 77
Fax: (+4) 021 369 01 77
1.Dr. Cristian-Mihail TEODORESCU
2.Dr. Alexandru Emil ALDEA
3.Dr. Dan MACOVEI
4.Dr. Nicolae POPA
5.Dr. Magdalena Lidia CIUREA
6.Dr. Sorina LAZANU
7.Dr. Mugurel TOLEA
8.Dr. Constantin Catalin NEGRILA
9.Dr. Maria-Ruxandra COSTESCU
10.Dr. Ionel STAVARACHE
11.Dr. Iuliana PASUK
12.Dr. Rodica GHITA
13.Dr. Marius Adrian HUSANU
14.Dr. George STAN
15.Dr. Marian NITA
16.Dr. Mihaela STEGARESCU
17.Nicoleta GHEORGHE
18.Ana Maria LEPADATU
19.George-Adrian LUNGU
20.Dr.Ion Viorel DINU
21.Adrian Claudiu POPA
22.Elena Laura STOFLEA
23.Dana Georgeta POPESCU
24.Bogdan OSTAHIE
25.Catalin PALADE
26.Laura Elena STOFLEA
27.Liviu Cristian TANASE
28.Radu DRAGOMIR
29.Cristian TACHE
30.Ioana Cristina BUCUR
31.Paul GARTNER 4
32.Andrei MANOLESCU 5
33.Toma STOICA 6
34.Paul RACEC 7
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
researcher
researcher
researcher
researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
engineer
engineer
senior researcher I
senior researcher I
senior researcher I
senior researcher III
4
Institut fur Theoretische Physik, Universitat Bremen, Germany
School of Science and Engineering, Reykjavik, Iceland
6
Forschungszentrum Julich, Peter Grunberg Institut, Julich, Germany
7
Weierstrass Institute for Applied Analysis and Stochastics, Berlin, Germany
5
15
Lab. 40
Laboratory of Optical Processes in Nanostructured Materials
HEAD:
Dr. Mihaela BAIBARAC
E-mail: [email protected]
Tel.: (+4) 021 369 01 77
Fax: (+4) 021 369 01 77
1. Dr. Ioan BALTOG
2. Dr. Ligia FRUNZA
3. Dr. Stefan FRUNZA
4. Dr. Mihai POPESCU
5. Dr. Mihai SECU
6. Dr. Marian SIMA
7. Dr. Anca STANCULESCU
8. Traian BEICA
9. Dr. Florin COTOROBAI
10. Dr. Adam LORINCZI
11. Lucian MIHUT
12. Dr. Corina SECU
13. Dr. Marcela SOCOL
14. Timucin VELULA
15. Dr. Irina Ionela ZGURA
16. Paul Constantin GANEA
17. Dr. Ilarie GONTIA
18. Dr. Mariana SIMA
19. Florinel SAVA
20. Dr. Oana RASOGA
21. Dr. Alin VELEA
22. Iulia ARGHIR
23. Ioana DUMITRESCU
24. Malvina SCOCIOREANU
25. Daniel-Iosif SIMANDAN
26. Ion SMARANDA
27. Cristina POPA
28.Dana DURAN
29. Mirela ILIE
30.Adelina MATEA
31 Carmen BREAZU
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher II
senior researcher II
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
senior researcher III
researcher
researcher
researcher
researcher
researcher
researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
assistant researcher
16
Lab. 50
Laboratory of Atomic Structures and Defects in Advanced Materials
HEAD:
Dr. Corneliu GHICA
E-mail: [email protected]
Tel.: (+4) 021 369 01 85
Fax: (+4) 021 369 01 77
1. Dr. Ion BIBICU
2. Dr. Serban CONSTANTINESCU
3. Dr. Lucian DIAMANDESCU
4. Dr. Nicoleta Maria GRECU
5. Dr. Leona Cristina NISTOR
6. Dr. Sergiu Vasile NISTOR
7. Dr. Nicoleta POPESCU-POGRION
8. Dr. Corneliu SARBU
9. Dr. Doina TARABASANU-MIHAILA
10. Dr. Valentin Serban TEODORESCU
11. Dr. Carmencita Doina MATEESCU
12. Adelina STANOIU
13. Dr. Mariana STEFAN
14. Dr. Alina BANUTA
15. Dr. Marcel FEDER
16. Dr. Daniela GHICA
17. Dr. Mihai VLAICU
18. Dr. Cristian Eugen SIMION
19. Jean Narcis BARASCU
20. Dr. Valentin Adrian MARALOIU
21. Dr. Ionel Florinel MERCIONIU
22. Raluca DAMIAN
23. Ioana VLAICU
24. Ecaterina PAULESCU
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher I
senior researcher II
senior researcher II
senior researcher II
senior researcher III
senior researcher III
senior researcher III
senior researcher III
researcher
assistant researcher
engineer
engineer
assistant researcher
PhD student
assistant researcher,
PhD student
assistant researcher
MSc student
17
INDETIR Laboratory for Specific Testing of Infrared Detectors
1.Dr.Gheorghe IORDACHE
2.Drd.Marius CIOANGHER
3.Drd. Adrian SLAV
senior researcher II
researcher
researcher
MAAS Laboratory for X-Ray Photoelectron Spectroscopy (XPS) Analysis
1.Dr. Mihail Florin LAZARESCU
2.Dr. Constantin LOGOFATU
senior researcher I
senior researc
VISITING GUESTS
Prof. Evangelos Hristoforou, Universitatera Tehnica din Atena, Grecia, 31.01.2013:
Magnetism against tumor
Hamidreza Khassaf, Sabanci University, Istanbul Turkey, Master Student, - Trim. I 2012
(two weeks) – supervisor L. Pintilie
Prof. Hong Li Suo, Beijing University of Technology-Beijing China: Superconducting
research at Beijing University of Technology (24.04.2012)
Mr. Yin SHI, Laboratoire Composants RF, CEA-LETI, Minatec Grenoble, France, 1017.06.2012, IFA-CEA project “Investigation of metal-ferroelectric interface at macro and nanoscale”,
Working stage in Lab. 10-Heterostructures Group
Prof. Patrik Hoffman, Head of Laboratory for Advanced Materials Processing,Swiss
Federal Laboratories for Materials Science and Technology - EMPA Thun, Switzerland
Dr. Robert Lowndes, Post-doc stage of 10 months in the framework of FP7-IFOX project
(March-December 2012)
Mohammadreza Khodabakhsh, Sabanci University, Istanbul Turkey, Master Student, Trim. IV 2012 (7 days) – supervisor L. Pintilie
18
Dr. Arnaud Magrez, EcolePolytechniqueFédérale de Lausanne and Dr. Dmitry Schur, Dr.
S. Yu Zaginaichenko, Institute for Problems of Materials Science of National Academy of
Science of Ukraine, cooperation Romania-Switzerland-Ukraine SCOPES project
IZ74Z0_137458/2012 : “Implementation in East Europe of new methods of synthesis and
functionalization of carbon nanotubesfor applications in the energy storage and sensors field”
Ph. D. THESES
Ion Ivan
Study of irreversible magnetization relaxation in strongly disordered superconductors
Ph D supervisor: Dr. Lucica Miu (Associated Professor Bucharest University)
February 2012
Mihaela Iuliana Sofronie
Magnetic properties and phase transitions in shape memory systems
Ph D supervisor: Dr. George Filoti (Associated Professor Bucharest University)
March 2012
Gabriel Alexandru Schinteie
Coordinaţie locală şi proprietăţi electronice în compuşi cu structură complexă
Ph D supervisor: Dr. George Filoti (Associated Professor Bucharest University)
March 2012
Constantin-Paul Ganea
Phase transitions and molecular dynamics of organic compounds incorporating functional
groups of esther, cyan, fluor type
Ph D supervisor: Dr. Stefan Frunza (Associated Professor Bucharest University)
March 2012
Marius-Cristian Cioangher
Study of some piezoceramics of tungsten-doped PZT type intended for special applications
Ph D supervisor: Dr. Cornel Miclea (Associated Professor Bucharest University)
April 2012
Florinel Sava
Structure modelling of carbon, silicon and chalcogenic nanomaterials
Ph D supervisor: Dr. Mihai Popescu (Associated Professor Bucharest University)
September 2012
19
Ana-Maria Lepadatu
The study of electrical properties of some nanostructures materials based on group IV
elements
Ph D supervisor: Dr. Magdalena Lidia Ciurea (Associated Professor Bucharest University)
September 2012
Malvina Scocioreanu
Composite materials of the type polymer/inorganic nanoparticles. Synthesis and optical
characterization
PhD supervisor: Dr. Ioan Baltog
September 2012
Cristina Busuioc (Jinga)
Microwave ceramics
Ph D supervisor: Prof. Dr. Ing. Ecaterina Andronescu (University POLITEHNICA of
Bucharest)
September 2012
AWARDS
Valeriu Moldoveanu: Winner of the Romanian Academy Prize „Radu Grigorovici” for the group
of papers entitled „Studies concerning the modelling of transport and charge transfer in
mesoscopic systems
Mihai Popescu: Order “Leonardo da Vinci” for Inventika, 2012
Ionel Stavarache, Ana-Maria Lepadatu, Iuliana Pasuk, Valentin Teodorescu, Magdalena Ciurea,
Best Paper Award 2012for “Preparation and electrical characterization of SiGe nanostructures”,
presented at 2011 International Semiconductor Conference-Sinaia 2011
20
HONORARY MEMBERSHIP
NIMP is honorary membership in various prestigious professional societies and
associations, such as:
• American Chemical Society
• German Physical Society
• European Soc of Appl Superconductivity
• Japanese Applied Physics Society (former)
• Cryogenic Soc. of Japan (former)
• Alumni JSPS, Romania (founding member)
3 NIMP distinguished researchers are Editor-in -chief or Co-Editor for 8 ISI journals.
Finally, 16 researchers are members in Editorial Board and Advisory Board for 11 ISI journals
(6 edited in Romania).
Also, NIMP is present in following databases:
• MyNet Research Empowering Collaboration (www.mynetresearch.com) internaţional resource for innovation centers in Eastern Europe and Central Asia. The
top five Romanian institutions in terms of research productivity are:
o Univ Bucharest
o Univ Babes Bolyai
o Romanian Acad
o Inst Atom Phys
o Natl Inst Mat Phys
• The CEEC IST NET portal (www.eu-istcommunity.net) – is a support instrument
for partners search and consortia creation in the field of research and innovation
concerning the information society technologies
•
•
Europartners Search (www.europartnersearch.net)
Resource Guide to Nanotechnology and Nanomaterials Services (denumit
NanoPerspective)
This guide includes a list of more 1000 organizations active in the field of Nanotehnology
and Nanomaterials.
• http://wikimapia.org/19116027/INCDFM-National-RD-Institute-of-Materials-PhysicsNIMP
• http://cercetare.ccib.ro/intranetHTML/infoFILES/infoHTML/File/2012_03_22_prezent
areINCDFM.pdf
• -http://www.ancs.ro/ro/articol/1325/de-cercetare-incd-institute-nationale-de-cercetaredezvoltare-incd-in-coordonarea-ancs-institutul-national-de-cercetare-dezvoltarepentru-fizica-materialelor-incdfm-bucuresti
• -http://www.infocercetare.ro/ro/Listeaza-Institutie/Ilfov-84_Localitate_Magurele86_Institutie_INCD-pentru-Fizica-Materialelor-INCDFM-253
21
MEMBERSHIPS IN NATIONAL RESEARCH
POLICY AND EVALUATION
ORGANIZATIONS
President of Consulting College for Research, Development and Innovation, Dr. A.
Aldea
Vicepresident of General Council of National Council of Academic Titles, Diplomas
and Certificates ( CNATDCU), Dr. L. Pintilie
Member in National Council of Scientific Research ( CNCS ), Dr. V. Moldoveanu
Member in National Council of Ethics, Dr. M. Baibarac
Member in National Council for Development and Innovation (CNDI), Dr. O. Crisan
Members in Physics Board of National Council of Academic Titles, Diplomas and
Certificates ( CNATDCU) :
• Dr. A. Aldea
• Dr. I. Enculescu
• Dr. C. Ghica
• Dr. V. Kuncser
• Dr. L. Miu
• Dr. C. Teodorescu
Members in Chemistry and Chemical Engineering Board of National Council of
Academic Titles, Diplomas and Certificates ( CNATDCU) :
• Dr. L.Frunza
• Dr. M. Baibarac
Members in Materials Engineering and Nanotechnology Board of National Council of
Academic Titles, Diplomas and Certificates ( CNATDCU) :
• Dr. P. Badica
• Dr. C. Teodorescu
Expert evaluators and monitoring for FP 7 and various programmes:
• Dr. L. Pintilie
• Dr. O. Crisan
• Dr. A. Stanculescu
• Dr. F. Vasiliu
• Dr. L. Frunza
MEMBERSHIP IN OTHER INTERNATIONAL ORGANIZATIONS
Badica Petre: member of American Chemical Society and German Physical Society
Banciu Marian Gabriel : member of IEEE: Microwave Theory and Techniques Society,
Antennas and Propagation Society
22
Ciurea Magdalena Lidia: member of European Physical Society
Crisan Ovidiu: member of Institute of Nanotechnology, UK
Diamandescu Lucian: - member of “American Nano Science”
-Romanian Representative in International Board on the Applications of
Mössbauer Effect - IBAME (2011-2017)
- member in Editorial Board of “ISRN Nanomaterials” (SUA)
Nedelcu Liviu: organizer of S5 session: Advanced Ceramics: From Micro- to Nanoscale, at
International Conference on Advanced Materials-ROCAM 2012, August 28-31, Brasov,
Romania (2012)
Nistor Sergiu Vasile: member of American Physical Society
Pintilie Lucian: member of European Physical Society
Popescu Mihai:- member of NACNOG (North Atlantic Consortium on Non-Oxide Glasses, 19
ţări din Europa, Canada şi SUA)
- member of VIP (Virtual Institute of Physics): http://www.infim.ro/~inst
Sandu Viorel: member of American Physical Society and Material Research Society Singapore
Sarbu Corneliu: member of Microscopical Society of America
Socol Marcela: member of International Organization on Crystal Growth
Stanculescu Anca: - member of International Organization on Crystal Growth
- member of SPIE
23
PUBLICATIONS AND
PRESENTATIONS
24
BOOKS
1. Angelakeris M, Crisan O,Martinez-Boubeta C
Magnetic Interfaces at the Nanoscale: From Fundamentals to Technological Applications
Special issue of Journal of Nanomaterials doi:10.1155/2012/619485, (2012)
2.Duta L, Popescu AC, Dorcioman G, Mihailescu IN, Stan GE, Zgura I, Enculescu I,
Dumitrescu I
Book chapter: ZnO thin films deposited on textile material substrates for biomedical
applications, pp. 207 – 210
In: Technological innovations in sensing and detection of chemical, biological, radiological,
nuclear threats and ecological terrorism; Part IV. Synthesis/Processing, ISBN 978-94-007-24877, Ed. 2012 Springer Series – NATO Science for Peace and Security Series A: Chemistry and
Biology, editors: Ashok Vaseashta, Eric Braman and Philip Susmann, (2012)
3.Jipa F, Zamfirescu M, Velea A, Popescu M, Dabu R
Book chapter: Femtosecond laser lithography in organic and non-organic materials
In: „Lithography”, INTECH, ISBN 980-953-307-530-8, Accepted (2012)
4.Kuncser V, Crisan O, Schinteie G. Tolea F, Palade P, Valeanu M, Filoti G
Magnetic Nanophases: From exchange coupled multilayers to nanopowders and nanocomposites
(book chapter)
In: Modern Trends in Nanoscience Editura Academiei, pp 197-222, (2012)
5.Miclea CF, Mota AC, Sigrist M
Book chapter: Vortex dynamics in superconductors without inversion symmetry
In: Non-Centrosymmetric Superconductors, Series Title: Lecture Notes in Physics, Editors: Ernst
Bauer, Manfred Sigrist, ISBN: 978-3-642-24623-4, Publisher: Springer Berlin Heidelberg,
(2012)
6.Stan GE, Ferreira JMF
Chapter 3: Magnetron sputtered BG thin films: An alternative biofunctionalization approach –
Peculiarities of bioglass sputtering and bioactivity behaviour, pp. 71 – 98
In: Ceramic Coatings – Applications in Engineering, ISBN: 978-953-51-0083-6, Ed. InTech
2012, editor: Feng Shi, Rijeka, Croatia (2012)
7.Stanculescu F, Stanculescu A
Chapter 12: Aromatic derivatives based materials for optoelectronic applications
In: Optoelectronics-Advanced Materials and Devices, Edited by Sergei L. Pyshkinand and John
M. Ballato, published by InTech Rijeka, Croatia, 2013, ISBN 978-953-51-0922-8 ; DOI
10.5772/51675
25
8.Stavarache I, Lepadatu AM, Ciurea ML
Book chapter : Ge nanodots embedded in a silica matrix
In: Nanomaterials and Nanostructures for Various Applications , Editors: Gheorghe Brezeanu,
Horia Iovu, Cornel Cobianu, Dan Dascãlu - Bucureºti : Editura Academiei Române, pp. 193 –
212, ISBN: 978-973-27-2169-8 (2012)
PAPERS IN ISI RANKED JOURNALS (with Impact Factor)
1.Aldica G, Batalu D, Popa S, Ivan I, Nita P, Sakka Y, Vasylkiv O, Miu L, Pasuk I, Badica P
Spark plasma sintering of MgB2 in the two-temperature route
Physica C-Superconductivity and ITS Applications, (2012), 477, pp. 43-50, 1.014
2.Aldica G, Popa S, Enculescu M, Badica P
Enhancement of critical current density and irreversibility field by Te or TeO2 addition to MgB2
bulk processed by spark plasma sintering
Scripta Materialia (2012), 66, 8, pp. 570 – 573, 2.699
3.Aldica G, Polosan S
Investigations of the non-isothermal crystallization of Bi4Ge3O12 (2:3) glasses
Journal of Non-Crystalline Solids, (2012), 358, 9, pp. 1221 – 1227, 1.537
4. Alexandrescu R, Morjan I, Dumitrache F, Birjega R, Fleaca C, Morjan I, Scarisoreanu M,
Luculescu CR, Dutu E, Kuncser VE, Filoti G, Vasile E, Ciupina V
Laser processing issues of nanosized intermetallic Fe-Sn and metallic Sn particles
Applied Surface Science, (2012), 258, 23, pp. 9421 – 9426, 2.103
26
5. Amarande L
Noniterative method for evaluation of the complex material constants of piezoelectric ceramics
in the radial vibration mode
Journal of the European Ceramic Society, (2012), 32, 5, pp. 1099 – 1104, 2.353
6. Angelakeris M, Crisan O, Martinez-Boubeta C
Magnetic interfaces at the nanoscale: from fundamentals to technological applications
Journal of Nanomaterials, (2012), 619485; 10.1155/2012/619485, 1.376
7. Angelescu DG, Vasilescu M, Anastasescu M, Baratoiu R, Donescu D, Teodorescu VS
Synthesis and association of Ag(0) nanoparticles in aqueous Pluronic F127 triblock copolymer
solutions
Colloids and Surfaces A-Physicochemical and Engineering Aspects, (2012), 394, pp. 57 – 66,
2.236
8. Apostol I, Damian V, Damian R, Nistor LC, Pascu A, Staicu A, Udrea C
Laser induced breakdown spectroscopy surface analysiscorrelated with the process of
nanoparticle production by laser ablation in liquids
Hyperfine Interactions, (2012) DOI 10.1007/s10751-012-0739-8, 0.763
9. Avadanei OG, Banciu MG, Nicolaescu I, Nedelcu L
Superior modes in high permittivity cylindrical dielectric resonator antenna excited by a central
rectangular slot
IEEE Transactions on Antennas and Propagation, (2012), 60, 11, pp. 5032 – 5038, 2.151
27
10. Badica P, Agostino A, Khan M, Mizanur R, Cagliero S, Plapcianu C, Pastero Linda,
Truccato M, Hayasaka Y, Jakob G
Bi-2212 and Y123 highly curved single-crystal-like objects: whiskers, bows and ring-like
structures
Superconductor Science & Technology, (2012), 25, pp. 10, 2.662
11. Badica P, Aldica G, Burdusel M, Endo K
Composites of MgB2 with Bi2O3, Bi, Sb2O3, or Sb obtained by ex-situ spark plasma sintering
Japanese Journal of Applied Physics, (2012), 51, pp. 11, 1.058
12. Baibarac M, Baltog I, Mihut L, Pasuk I, Lefrant S
Casimir effect demonstrated by Raman spectroscopy on trilayer graphene intercalated into stiff
layered structures of surfactant
Carbon, (2012), 51, pp. 134 – 142, 5.378
13. Baibarac M, Massuyeau F, Wery J, Baltog I, Lefrant S
Raman scattering and anti-Stokes luminescence in poly-paraphenylene vinylene/carbon
nanotubes composites
Journal of Applied Physics, (2012), 111, pp. 8, 2.168
14. Baibarac M, Baltog I, Wery J, Lefrant S, Mevellec JY
Abnormal anti-stokes Raman emission and infrared dichroism studies on poly(pphenylenevinylene)/single-walled carbon nanotube composites
Journal of Physical Chemistry C, (2012), 116, 48, pp. 25537 – 25545, 4.805
28
15. Baltog I, Baibarac M, Mihut L, Smaranda I, Lefrant S
Nonlinear optical processes manifesting as Anderson localization of light in mesoscopic
materials
Proceedings of the Romanian Academy, Series A, vol.13, (2012), pp. 109-117, 0.28
16. Berbecaru C, Stan GE, Pina S, Tulyaganov DU, Ferreira JMF
The bioactivity mechanism of magnetron sputtered bioglass thin films
Applied Surface Science, (2012), 258, 24, pp. 9840 – 9848, 2.103
17. Besleaga C, Stan GE, Galca AC, Ion L, Antohe S
Double layer structure of ZnO thin films deposited by RF-magnetron sputtering on glass
substrate
Applied Surface Science, (2012), 258, 22, pp. 8819 – 8824, 2.103
18. Besleaga C, Ion L, Ghenescu V, Socol G, Radu A, Arghir I, Florica C, Antohe S
Transparent indium zinc oxide thin films used in photovoltaic cells based on polymer blends
Thin Solid Films, (2012), 520, 22, pp. 6803 – 6806, 1.89
19. Birsan A, Palade P, Kuncser VE
Half-metallic state and magnetic properties versus the lattice constant in Ti2CoSn Heusler
compound: An ab initio study
Solid State Communications, (2012), 152, 24, pp. 2147 – 2150, 1.649
20. Borodianska H, Demirskyi D, Sakka Y, Badica P, Vasylkiv O
Grain boundary diffusion driven spark plasma sintering of nanocrystalline zirconia
29
Ceramics International, (2012), 38, 5, pp. 4385 – 4389, 1.751
21. Bucur C, Badea M, Calu L, Marinescu D, Grecu MN, Stanica N, Chifiriuc MC, Olar R
Thermal behaviour of some new complexes with decaaza bismacrocyclic ligand as potential
antimicrobial species
Journal of Thermal Analysis and Calorimetry, (2012), 110, 1, pp. 235 – 241, 1.604
22. Burdusel M, Aldica G, Popa S, Enculescu M, Badica P
MgB2 with addition of Sb2O3 obtained by spark plasma sintering technique
Journal of Materials Science, (2012), 47, 8, pp. 3828 – 3836, 2.015
23. Busuioc C, Jinga SI, Stoleriu S, Nedelcu L, Andronescu E
Ba(Zn1/3Ta2/3)O-3 perovskite ceramics doped with Nb5+, Ce4+ or Yb3
Journal of Optoelectronics and Advanced Materials, (2012), 14, 3-4, pp. 238 – 244, 0.457
24. Cagliero S, Borfecchia Elisa, Mino L, Calore L, Bertolotti F, Martinez-Criado G, Operti L,
Agostino A, Truccato M, Badica P, Lamberti C
Insight into non-linearly shaped superconducting whiskers via a synchrotron nanoprobe
Superconductor Science & Technology, (2012), 25, pp. 12, 2.662
25. Cernea M, Secu CE, Vasile BS, Secu M
Structural and optical characterization of sol-gel derived Tm-doped BaTiO3 nanopowders and
ceramics
Current Applied Physics, (2012), 13, 1, pp. 137 – 141, 1.9
30
26. Cernea M, Trupina L, Dragoi C, Vasile BS, Trusca R
Structural and piezoelectric characteristics of BNT-BT0.05 thin films processed by sol-gel
technique
Journal of Alloys and Compounds, (2012), 515, pp. 166 – 170, 2.289
27. Cernea M, Vasile BS, Capiani C, Ioncea A, Galassi C
Dielectric and piezoelectric behaviors of NBT-BT0.05 processed by sol-gel method
Journal of the European Ceramic Society, (2012), 32, 1, pp. 133 – 139, 2.353
28. Cernea M, Poli G, Aldica GV, Berbecaru C, Vasile BS, Galassi C
Preparation and properties of nanocrystalline BNT- BTx piezoelectric ceramics by sol-gel and
spark plasma sintering
Current Applied Physics, (2012), 12, 4, pp. 1100 – 1105, 1.9
29. Cernea M, Trupina L, Dragoi C, Galca AC, Trinca L
Structural, optical, and electric 2properties of BNT-BT0.08 thin films processed by sol-gel
technique
Journal of Materials Science, (2012), 47, 19, pp. 6966 – 6971, 2.015
30. Cernea M, Galassi C, Vasile BS, Capiani C, Berbecaru C, Pintilie I, Pintilie L
Structural, dielectric, and piezoelectric properties of fine-grained NBT-BT0.11 ceramic derived
from gel precursor
Journal of the European Ceramic Society, (2012), 32, 10, pp. 2389 – 2397, 2.353
31
31. Cernea M, Fochi F, Aldica GV, Vasile BS, Trusca R, Galassi C
Spark-plasma-sintering temperature dependence of structural and piezoelectric properties of
BNT-BT0.08 nanostructured ceramics
Journal of Materials Science, (2012), 47, 8, pp. 3669 – 3673, 2.015
32. Cimpoiasu E, Sandu V, Levin GA, Simpson A, Lashmore D
Angular magnetoresistance of stretched carbon nanotube sheets
Journal of Applied Physics, (2012), 111, pp. 12, 2.168
33. Ciobanu CS, Iconaru SL, Le Coustumer P, Predoi D
Vibrational investigations of silver-dovep hydroxyapatite with antibacterial properties
Journal of Spectroscopy, (2012) Vol
http://dx.doi.org/101155/2013/471061, 0.805
2013,
Article
ID
471061,
5
pages,
34. Ciobanu CS, Iconaru SL, Gyorgy E, Radu M, Costache M, Dinischiotu A, Le Coustumer P,
Lafdi K, Predoi D
Biomedical properties and preparation of iron oxide-dextran nanostructures by MAPLE
technique
Chemistry Central Journal, (2012), 6, pp. 17, 3.281
35. Ciobanu CS, Iconaru SL, Le Coustumer P, Constantin LV, Predoi D
Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and
gram-negative bacteria
Nanoscale Research Letters, (2012), 7, pp. 324, 2.726
32
36. Ciobanu CS, Iconaru SL, Massuyeau F, Constantin LV, Costescu A, Predoi D
Synthesis, structure and
nanocrystalline powders
luminescent
properties
Journal
of
Nanomaterials,
(2012),
http://dx.doi.org/101155/2012/942801, 1.376
of
Article
europium-doped
ID
hydroxyapatite
942801,
9
pages,
37. Ciobanu M, Cojocaru B, Teodorescu CM, Vasiliu F, Coman SM, Leitner W, Parvulescu VI
Heterogeneous amination of bromobenzene over titania-supported gold catalysts
Journal of Catalysis, (2012), 296, pp. 43 – 54, 6.002
38. Cojocaru A, Sima M
Electrochemical investigation of the deposition/dissolution of selenium in choline chloride with
urea or ethylene glycol ionic liquids
Revista de Chimie, (2012), 63, 2, pp. 217 – 223, 0.599
39. Comanescu C, Capurso Giovanni, Maddalena A
Nanoconfinement in activated mesoporous carbon of calcium borohydride for improved
reversible hydrogen storage
Nanotechnology, (2012), 23, pp.38, 3.979
40. Comorosan S, Polosan S, Popescu I, Paslaru L, Nastase A, Mitrica R, Ionescu E
Antioxidant effects induced in biological macromolecular systems by high density photons
through localized excitations
Biochimica et Biophysica Acta-Bioenergetics, (2012), 1817, pp. S130 - S130, 4.843
33
41. Constantin LV, Iconaru SL, Ciobanu CS
Europium doped hydroxyapatite for applications in environmental field
Romanian Reports in Physics, (2012), 64, 3, pp.788 – 794, 0.5
42. Constantinescu C, Ion V, Galca AC, Dinescu M
Morphological, optical and electrical properties of samarium oxide thin films
Thin Solid Films, (2012), 520, 20, pp. 6393 – 6397, 1.89
43. Constantinescu S, Udubasa SS, Udubasa G, Kuncser V, Popescu-Pogrion N, Mercioniu I,
Feder M, Mössbauer
TEM/SAED and XRD investigation on waste dumps of the Valea lui Stan gold mines
Hyperfine Interactions 208 (2012), pp. 79-84 , 0.763
44. Costescu RM, Gheorghe NG, Husanu MA, Lungu GA, Macovei D, Pintilie I, Popescu DG,
Teodorescu CM
Epitaxial ferromagnetic samarium and samarium silicide synthesized on Si(001)
Journal of Materials Science, (2012), 47, 20, pp. 7225 – 7234, 2.015
45. Costescu RM, Lungu GA, Socol G, Gheorghe NG, Macovei D, Negrila CC, Logofatu C,
Husanu MA, Popescu DG, Tache CA, Teodorescu CM
Atomic structure and magnetism of pld deposited Tio(2):Fe
Digest Journal of Nanomaterials and Biostructures, (2012), 7, 1, pp. 73 – 78, 1.2
34
46. Cotorobai VF
Drop images with reflection spots: improved processing for determination of wetting contact
angles
Romanian Reports in Physics, (2012), 64, 2, pp. 467 – 481, 0.5
47. Crisan AD, Crisan O
AFM studies of metallic and organic nanosized structures ion beam sputtered onto functionalised
surfaces
Materials Science and Technology, (2012), 28, 4, pp. 460 – 466, 0.772
48. Dobrinescu C, Iorgulescu EE, Mihailciuc C, Macovei D, Wuttke S, Kemnitz E, Parvulescu
VI, Coman SM
One-pot hydroacetylation of menadione (Vitamin K3) to menadiol diacetate (Vitamin K4) by
heterogeneous catalysis
Advanced Synthesis & Catalysis, (2012), 354, 7, pp. 1301 – 1306, 6.048
49. Donescu Dan, Raditoiu Valentin, Spataru CI, Somoghi Raluca, Ghiurea M, Radovici C,
Fierascu RC, Schinteie G, Leca A, Kuncser VE
Superparamagnetic magnetite-divinylbenzene-maleic anhydride copolymer nanocomposites
obtained by dispersion polymerization
European Polymer Journal, (2012), 48, 10, pp. 1709 – 1716, 2.739
50. Dragoi C, Gheorghe NG, Lungu GA, Trupina L, Ibanescu AG, Teodorescu CM
X-ray photoelectron spectroscopy of pulsed laser deposited Pb(Zr,Ti)O3-delta
Physica Status Solidi A-Applications and Materials Science, (2012), 209, 6, pp. 1049 – 1052,
1.463
35
51. Duta L, Dorcioman G, Popescu A C, Mihailescu I N, Nita P, Mercioniu I, Birsan A, Bibicu
I, Constantinescu S, Popescu-Pogrion N
Structural investigations on electrodes - electrolytes systems for intermediate temperature solid
oxide fuel cell applications
Optoelectronics and Advanced Materials, Rapid Communications 6, (2012), pp. 1073-1080,
0.304
52. Enache M, Preda L, Negrila CC, Lazarescu MF, Mercioniu I, Santos E, Anastasescu M,
Dobrescu G, Lazarescu V
Electronic effects at self-assembled 4,4 '-thio-bis-benzenethiolate protected Au nanoparticles on
p-GaAs (100) electrodes
Electrochimica Acta, (2012), 77, pp. 8 – 16, 3.832
53. Enculescu M, Preda N, Matei E, Enculescu I
Luminescent micro- and nanofibers based on novel europium phthalate complex
Materials Chemistry and Physics, (2012), 136, 1, pp. 51 – 58, 2.234
54. Endo K, Badica P, Arisawa S, Kezuka H, Endo T
Growth aspects of thin-film composite heterostructures of oxide multicomponent perovskites for
electronics
Japanese Journal of Applied Physics, (2012), 51, pp. 11, 1.058
55. Finch KBH, Richards RM, Richel A, Medvedovici AV, Gheorghe NG, Verziu M, Coman SM,
Parvulescu VI
Catalytic hydroprocessing of lignin under thermal and ultrasound conditions
Catalysis Today, (2012), 196, 1, pp. 3 – 10, 3.407
36
56. Florian M, Gies C, Gartner P, Jahnke F
Improved antibunching by using high-excitation pulses from a single semiconductor quantum
dot-a theoretical study
Journal of the Optical Society of America B-Optical Physics, (2012), 29, 2, pp.A31 - A35,
2.185
57. Frunza L, Gheorghe NG, Ganea CP, Eckelt R, Kosslick H
Oxidation activity of horseradish peroxidase hosted in molecular sieves: spectroscopic
investigations show hindering of the enzyme activity
Reaction Kinetics Mechanisms and Catalysis, (2012), 105, 1, pp. 195 – 205, 0.829
58. Galca AC, Stan GE, Trinca LM, Negrila CC, Nistor LC
Structural and optical properties of c-axis oriented aluminum nitride thin films prepared at low
temperature by reactive radio-frequency magnetron sputtering
Thin Solid Films, (2012), 524, pp. 328 – 333, 1.89
59. Galca AC, Socol G, Craciun V
Optical properties of amorphous-like indium zinc oxide and indium gallium zinc oxide thin films
Thin Solid Films, (2012), 520, 14, pp. 4722 – 4725, 1.89
60. Galca AC, Preda N, Secu CE, Luculescu CR, Secu M
Spectroscopic ellipsometry investigations of Eu-doped oxy-fluoride glass and glass-ceramics
Optical Materials, (2012) 34, 8, pp. 1493 – 1496, 2.023
37
61. Ganea CP
New approach of the ac electrode polarization during the measurements of impedance spectra
Romanian Journal of Physics, (2012), 57, 3-4, pp. 664 – 675 0.414
62. Gheorghe C, Lupei A, Voicu F, Enculescu M
Sm3+-doped Sc2O3 polycrystalline ceramics: Spectroscopic investigation
Journal of Alloys and Compounds, (2012), 535, pp. 78 – 82, 2.289
63. Gheorghe NG, Husanu MA, Lungu GA, Costescu RM, Macovei D, Popescu DG,
Teodorescu CM
Reactivity, magnetism and local atomic structure in ferromagnetic fe layers deposited on Si (001)
Digest Journal of Nanomaterials and Biostructures, 2012; 7; 1; 373 – 384
1.2
64. Gheorghe NG, Husanu MA, Lungu GA, Costescu RM, Macovei D, Teodorescu CM
Atomic structure and reactivity of ferromagnetic Fe deposited on Si (001)
Journal of Materials Science, (2012), 47, 4, pp. 1614 – 1620, 2.015
65. Gherendi M, Zoita VL, Craciunescu T, Johnson M.G, Pantea A, Baltog I, Edlington T,
Hellesen C, Kiptily V, Conroy S, Murari A, Popovichev S
Neutron field parameter measurements on the JET tokamak by means of super-heated fluid
detectors
Review of Scientific Instruments, (2012), 83, pp. 10, 1.367
38
66. Ghita RV, Cotirlan C, Ungureanu F, Florica C, Negrila CC
Study of thiols deposition on GaAs
Optoelectronics and Advanced Materials - Rapid Communications, (2012), 6, 1-2, pp. 239 – 244
0.304
67. Guo Zhichao, Suo Hongli, Liu Zhiyong, Sandu V, Aldica G, Badica P
The critical current density of SiC-doped MgB2 as determined from the Campbell penetration
depth using the tunnel-diode resonator technique
Optoelectronics and Advanced Materials – Rapid Communications, 6, (2012), pp. 976-979,
0.304
68. Iconaru SL, Prodan AM, Le Coustumer P, Predoi D
Synthesis and antibacterial and antibiofilm activity of iron oxide glycerol nanoparticles obtained
by coprecipitation method
Journal of Chemistry, (2012), Vol.25, Nr.8, DOI 10.1007/s10948-012-1855-z, 0.516
69. Iconaru SL, Andronescu E, Ciobanu CS, Prodan AM, Le Coustumer P. Predoi D
Biocompatible magnetic iron oxide nanoparticles doped dextran thin films produced by spin
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Digest Journal of Nanomaterials and Biostructures, (2012), 7, 1, pp. 399 – 409, 1.2
70. Iconaru SL, Prodan AM, Motelica-Heino M, Sizaret S, Predoi D
Synthesis and characterization of polysaccharide-maghemite composite nanoparticles and their
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Nanoscale Research Letters, (2012), 7, pp. 576, 2.726
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71. Iconaru SL, Ciobanu CS, Prodan AM, Predoi D
The antimicrobial activity of fabricated iron oxide nanoparticles
Febs Journal, (2012), 279, pp. 98 – 98, 3.79
72. Iconaru SL, Ciobanu CS, Le Coustumer P, Predoi D
Structural characterization and magnetic properties of iron oxides biological polymers Journal
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73. Ion FM, Barna V, Vulpe S, Radu A, Filimon A, Heimann G
Fabrication and characterization of thin polyaniline films obtained by glancing angle deposition
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Digest Journal of Nanomaterials and Biostructures, (2012), 7, 4, pp. 1481 – 1490
1.2
74. Ionascu AM, Raikova G, Mladenova E, Mercioniu I
Electrochemical analysis of solid oxide electrolytes for intermediate temperature fuel cell
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75. Ionita G, Ghica C, Turcu I, Ionita P
Reversible aggregation between nanoparticles induced by acid-base interactions
Chemical Physics Letters, (2012), 546, PP. 133 – 135, 2.337
76. Jinga SI, Stoleriu S, Busuioc C
Microwave dielectric properties of Ba(Zn1/3Ta2/3)O-3 ceramics doped with Nb2O5, MnO2 or
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77. Junkes A, Pintilie I, Fretwurst E, Eckstein D
A contribution to the identification of the E5 defect level as tri-vacancy (V-3)
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78. Kessler CA, Reischle M, Hargart F, Schulz WM, Eichfelder M, Rossbach R, Jetter M,
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Strong antibunching from electrically driven devices with long pulses: A regime for quantum-dot
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79. Khassaf H, Ibanescu GA, Pintilie I, Misirlioglu IB, Pintilie L
Potential barrier increase due to Gd doping of BiFeO3 layers in Nb:SrTiO3-BiFeO3-Pt structures
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Pplied Physics Letters, (2012), 100, PP. 25, 3.844
80. Kuncser VE, Palade P, Schinteie G, Sandu SG, Trupina L, Lungu GA, Gheorghe NG,
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Interface characterization and atomic intermixing processes in Be/W bilayers deposited on
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81. Lazanu I, Lazanu S
Interactions of exotic particles with ordinary matter
Nucl. Instr. Meth. (2012), 278, pp. 70-77, 1.211
82. Lazanu S, Slav A, Lepadatu AM, Stavarache I, Palade C, Iordache G, Ciurea ML
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Effects produced by iodine irradiation on high resistivity silicon
Applied Physics Letters, (2012), 101, pp. 24, 3.844
83. Le Febvrier A, Deputier S, Bouquet V, Demange V, Ollivier S, Galca AC, Dragoi C, Radu R,
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Ferroelectric and dielectric multilayer heterostructures based on KTa0.65Nb0.35O3 and Bi1.5xZn0.92-yNb1.5O6.92-1.5x-y grown by pulsed laser deposition and chemical solution deposition
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84. Le Febvrier A, Galca AC, Corredores Y, Deputier S, Bouquet V, Demange V, Castel X,
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85. Lefrant S, Buisson JP, Mevellec JY, Massuyeau F, Wery J, Baibarac M, Baltog I
Anti-stokes Raman scattering and luminescence in carbon nanotube nanostructures molecular
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86. Lungu GA, Apostol NG, Morariu M, Teodorescu CM
Band ferromagnetism in systems with linear density of states
Digest Journal of Nanomaterials and Biostructures, (2012), 7, 4, pp. 1615 - 1626 1.2
87. Marcu A, Trupina L, Zamani R, Arbiol J, Grigoriu C, Morante JR
Catalyst size limitation in vapor-liquid-solid ZnO nanowire growth using pulsed laser deposition
Thin Solid Films, (2012), 520, 14, pp. 4626 – 4631, 1.89
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88. Mardare D, Yildiz A, Apetrei R, Rambu P, Florea D, Gheorghe NG, Macovei D, Teodorescu
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The Meyer-Neldel rule in amorphous TiO2 films with different Fe content
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89. Matei E, Enculescu M, Preda N, Enculescu I
ZnO morphological, structural and optical properties control by electrodeposition potential
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Materials Chemistry and Physics, (2012), 134, 2-3, pp.988-993, 2.234
90. Melinte G, Baia M, Georgescu D, Baia L, Iancu V, Diamandescu L, Popescu T, Cotet LC,
Barbu-Tudoran L, Danciu V, Simon S
The influence of the Au nanoparticles dimension on the photocatalytic performances of TiO2-Au
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Acta Physica Polonica A, (2012), 121, 1, pp. 208 – 210, 0.444
91. Mercioniu I, Stan GE, Bercia R, Ciuc S, Popescu-Pogrion N
Obtaining and characterization of HA/Y2O3:alpha Al2O3 system for bioapplications
Digest Journal of Nanomaterials and Biostructures, (2012), 7, 3, pp. 917 – 932, 1.2
92. Miculescu F, Stan GE, Ciocan LT, Miculescu M, Berbecaru A, Antoniac I
Cortical bone as resource for producing biomimetic materials for clinical use
Digest Journal of Nanomaterials and Biostructures, (2012), 7, 4, pp. 1667 – 1677,
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93.Mihai C, Velea A, Roman N, Tugulea L, Moldovan NI
Modeling the slaving of structural fluctuations in bio-molecules to those of nearby water
Digest Journal of Nanomaterials and Biostructures, (2012), 7, 3, pp. 907 – 915,
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94. Mindru C, Ganea CP, Alexandru J
Dielectric relaxation of pure TGS crystals
Journal of Optoelectronics and Advanced Materials, 14 (2012) pp. 157-162, 0.457
95. Mihai C, Velea A, Roman N, Tugulea L, Moldovan NI
Impact of solute molecular properties on the organization of nearby water: a cellular automata
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96. Mindru I, Gingasu D, Marinescu G, Patron L, Diamandescu L, Feder M, Calderon-Moreno
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97. Mitrica R, Popescu I, Paslaru L, Badila D, Polosan S, Cristache L, Ionescu E, Tataru C,
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High-density green photons effects on NaCl solutions detected by red blood cells membranes
Digest Journal of Nanomaterials and Biostructures, (2012), 7, 1, pp. 227 – 235, 1.2
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98. Miu D, Noji T, Adachi T, Koike Y, Miu L
On the nature of the second magnetization peak in FeSe1-xTex single crystals
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99. Miu L
Vortex depinning temperature in YBa2Cu3O7 films with BaZrO3 nanorods
Physical Review B, (2012), 85, pp. 10, 3.691
100. Miu L
Non-monotonous temperature variation of the magnetization relaxation rate in YBCO films with
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101. Moldoveanu V, Tolea M, Tanatar B
Mesoscopic Fano effect in a spin splitter with a side-coupled quantum dot
Physics Letters A, (2012), 376, 10-11, pp. 1078 – 1083, 1.632
102. Morjan I, Dumitrache F, Alexandrescu R, Fleaca C, Birjega R, Luculescu CR, Soare I,
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Laser synthesis of magnetic iron-carbon nanocomposites with size dependent properties
Advanced Powder Technology, (2012), 23, 1, pp. 88 – 96, 1.612
103. Nagaraj B, Divya TK, Barasa M, Krishnamurthy NB, Dinesh R, Negrila CC, Predoi D
Phytosynthesis of gold nanoparticles using caesalpinia pulcherrima (peacock flower) flower
extract and evaluation of their antimicrobial activities
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Digest Journal of Nanomaterials and Biostructures, (2012), 7, 3, pp. 899 – 905, 1.2
104. Nagaraj B, Malakar B, Divya TK, Krishnamurthy NB, Liny P, Dinesh R, Iconaru SL,
Ciobanu CS
Synthesis of plant mediated gold nanoparticles using flower extracts of carthamus tinctorius l.
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Digest Journal of Nanomaterials and Biostructures, (2012), 7, 3, pp. 1289 – 1296, 1.2
105. Nedelcu L, Mandache NB, Toacsan MI, Vlaicu AM, Banciu MG, Ioachim A, Gherendi F,
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Dielectric properties of Ba(Zn1/3Ta2/3)O-3 thin films on Pt-coated Si substrates
Thin Solid Films, (2012), 522, pp. 112 – 116, 1.89
106. Nicolescu M, Anastasescu M, Preda S, Stroescu H, Stoica M, Teodorescu VS, Aperathitis
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Influence of the substrate and nitrogen amount on the microstructural and optical properties of
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Applied Surface Science, (2012), 261, pp. 815 – 823, 2.103
107. Nistor SV, Ghica D, Stefan M, Vlaicu ID, Barascu JN, Bartha C
Magnetic defects in crystalline Zn(OH)(2) and nanocrystalline ZnO resulting from its thermal
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108. Nita M, Marinescu DC, Manolescu A, Ostahie B, Gudmundsson V
Persistent oscillatory currents in a 1D ring with Rashba and Dresselhaus spin-orbit interactions
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Physica E-Low-Dimensional Systems & Nanostructures, (2012), 46, pp. 12 – 20, 1.532
109. Palade P, Comanescu C, Mercioniu I
Improvements of hydrogen desorption of lithium borohydride by impregnation onto MSU-H
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110. Pana O, Soran ML, Leostean C, Macavei S, Gautron E, Teodorescu CM, Gheorghe NG,
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Interface charge transfer in polypyrrole coated perovskite manganite magnetic nanoparticles
Journal of Applied Physics, (2012), 111, pp.4, 2.168
111. Pervolaraki M, Sima F, Socol G, Teodorescu CM, Gheorghe NG, Socol M, Mihailescu IN,
Moushi EE, Tasiopoulos AJ, Athanasopoulos GI, Viskadourakis Z, Giapintzakis J
Matrix assisted pulsed laser evaporation of Mn-12(Propionate) thin films
Applied Surface Science, (2012), 258, 23, pp. 9471 – 9474, 2.103
112. Pervolaraki M, Pasuk I, Stan GE, Giapintzakis J
Pulsed laser deposition of highly textured La5Ca9Cu24O41 films on SrLaAlO4 (100) and
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Applied Surface Science, (2012), 258, 23, pp. 9475 – 9479, 2.103
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113. Petrescu L, Cinteza O, Voiculescu AM, Rosu T, Enculescu I Matei E, Georgescu S, Birjega
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Interaction of NaYF4:Er:Yb nanoparticles with phospholipid monolayers as models of biological
membranes
Revista de Chimie, (2012), 63, 9, pp. 956 – 961
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114. Petrisor T Jr., Gabor MS, Tiusan C, Galluzzi V, Celentano G, Popa S, Boulle A, Petrisor T
Magnetic pinning effects of epitaxial LaxSr1-xMnO3 nanostructured thin films on YBa2Cu3O7delta layers
Journal of Applied Physics, (2012), 112, pp. 5, 2.168
115. Pintilie I, Pasuk I, Ibanescu GA, Negrea R, Chirila C, Vasile E, Pintilie L
The impact of the Pb(Zr,Ti)O-3-ZnO interface quality on the hysteretic properties of a metalferroelectric-semiconductor structure
Journal of Applied Physics, (2012), 112, pp. 10, 2.168
116. Pintilie L, Pasuk I, Negrea R, Filip LD, Pintilie I
The effect of the top electrode interface on the hysteretic behavior of epitaxial ferroelectric
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Journal of Applied Physics, (2012), 112, pp. 6, 2.168
117. Plapcianu C, Agostino A, Badica P, Aldica GV, Bonometti E, Ieluzzi G, Popa S, Truccato
M, Cagliero S, Sakka Y, Vasylkiv O, Vidu R
Microwave synthesis of fullerene-doped MgB
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118. Polosan S, Radu IC, Tsuboi T
Photoluminescence and magnetic circular dichroism of IrQ(ppy)(2)-5Cl
Journal of Luminescence, (2012), 132, 4, pp. 998 – 1002, 2.102
119. Popa NC, Balzar D
Elastic strain and stress determination by Rietveld refinement: generalized treatment for textured
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120. Popescu DG, Sterian P, Bercia R, Bostan C
Second harmonic generation in photonic crystals: numerical simulation
Journal of Optoelectronics and Advanced Materials, 14, (2012), pp. 356-362, 0.457
121. Popescu M, Stanford R
Ovshinsky prize for excellence in amorphous chalcogenides
Physica Status Solidi B-Basic Solid State Physics, (2012), 249, 10, pp.1835-1836, 1.316
122. Popescu M, Velea A
Possible mechanisms of switching in amorphous chalcogenides
Physica Status Solidi B-Basic Solid State Physics, (2012), 249, 10, pp.1966 – 1971, 1.316
123. Preda N, Enculescu M, Gherendi F, Matei E, Toimil-Molares ME, Enculescu I
Synthesis of CdS nanostructures using template-assisted ammonia-free chemical bath deposition
Journal of Physics and Chemistry of Solids, (2012), 73, 9, pp.1082 – 1089, 1.632
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124. Preda N, Enculescu M
Synthesis and characterization of bead-like particles based on chitosan and vinyl polymers
Journal of Polymer Research, (2012), 19, pp. 9, 1.733
125. Predoi D, Ciobanu CS, Radu M, Costache M, Dinischiotu A, Popescu C, Axente E,
Mihailescu IN, Gyorgy E
Hybrid dextran-iron oxide thin films deposited by laser techniques for biomedical applications
Materials Science & Engineering C-Materials For Biological Applications, (2012), 32, 2, pp.296
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126. Prodan AM, Le Coustumer P, Predoi D
Evaluation of antibacterial effect of silver doped hydroxyapatite nanoparticles
FEBS Journal, (2012), 279, pp. 98 – 98, 3.79
127. Raditoiu V, Diamandescu L, Corobea MC, Raditoiu A, Popescu-Pogrion N, Nicolae CA
Facile hydrothermal route for the synthesis of alpha-FeOOH with controlled morphology
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128. Radu IC, Polosan S, Enculescu I, Iovu H
Cathodoluminescence and Raman analysis of the finite-size effects in mer-Alq(3) structure
Optical Materials (2012), 35(2, pp. 268-273, 2.023
129. Radu M, Iconaru SL, Predoi D, Costache M, Dinischiotu A
Assessing toxicity of two types of magnetite nanoparticles in human hepatocarcinoma cells
Febs Journal, (2012), 279, pp. 205 – 205, 3.79
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130. Raghavendra Reddt V, Crisan O, Gupta A, Banerjee A, Kuncser V
Tuning exchange spring effects in FePt/Fe(Co) magnetic bilayers
Thin Solid Films, 520, (2012), pp. 2184-2189 1.89
131. Rasoga O, Vacareanu L, Grigoras M, Enculescu M, Socol M, Stanculescu F, Ionita I,
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Optical and electrical properties of arylenevinylene compounds thin films prepared by vacuum
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132. Reddy VR, Crisan O, Gupta A, Banerjee A, Kuncser VE
Tuning exchange spring effects in FePt/Fe(Co) magnetic bilayers
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133. Ren J, Li B, Yang G, Xu W, Zhang Z, Secu M, Bercu V, Zeng H, Chen G
Broadband near-infrared emission of chromium-doped sulfide glass-ceramics containing Ga2S3
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Optics Letters, (2012), 37, 24, pp. 5043 – 5045, 3.399
134. Sahoo B, Keune W, Kuncser VE, Roehlsberger R
As-grown superconducting MgB2 thin films prepared at extreme deposition conditions
Superconductor Science & Technology, (2012), 25, pp. 1, 2.662
135. Samide A, Tutunaru B, Negrila CC, Prunaru I
Surface analysis of inhibitor film formed by 4-amino-N-(1,3-thiazol-2-yl) benzene sulfonamide
on carbon steel surface in acidic media
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136. Samide A, Tutunaru B, Dobritescu A, Negrila CC
Study of the corrosion products formed on carbon steel surface in hydrochloric acid solution
Journal of Thermal Analysis and Calorimetry, (2012), 110, 1, pp. 145 – 152, 1.604
137. Sandu V, Cimpoiasu E, Aldica G, Popa S, Sandu E, Vasile B, Hurduc N, Nor I
Use of preceramic polymers for magnesium diboride composites
Physica C-Superconductivity and ITS Applications, (2012), 480, pp.102-107, 1.014
138. Sandu V, Nicolescu MS, Kuncser VE, Popa S, Pasuk I, Sandu E
Effect of nucleators and intermediates on the magnetic properties of nanosized magnetite
obtained by glass crystallization
Journal of Computational and Theoretical Nanoscience, (2012), 9, pp. 1541-1545, 0.912
139. Sandu V, Popa S, Nicolescu MS, Enachescu M, Sandu E
Effect of tritium loading on the superconducting properties of Niobium and Tantalum
Journal of Superconductivity and Novel Magnetism, (2012), 25, 6, pp. 1799 – 1804, 0.65
140. Sandu V
Pinning-force scaling and its limitation in intermediate and high temperature, superconductors
Modern Physics Letters B, (2012), 26, 14, 0.47
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141. Sandu V, Nicolescu MS, Kuncser V, Popa S, Pasuk I, Ghica C, Sandu E
Structure and magnetic properties of nanosized magnetite obtained by glass recrystallization
Journal of Nanoscience and Nanotechnology, (2012), 12, 6, pp. 5043-5050, 1.563
142. Sandu V, Aldica G, Damian R, Zhi-Chao G, Hong-Li S
One-step synthesis and sintering of MgB2 by spark plasma sintering
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143. Schumacher S, Foerstner J, Zrenner A, Florian M, Gies C, Gartner P, Jahnke F
Cavity-assisted emission of polarization-entangled photons from biexcitons in quantum dots with
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Optics Express, (2012), 20, 5, pp. 5335 – 5342, 3.587
144. Scocioreanu M, Baibarac M, Baltog I, Pasuk I, Velula T
Photoluminescence and Raman evidence for mechanico-chemical interaction of polyanilineemeraldine base with ZnS in cubic and hexagonal phase
Journal of Solid State Chemistry, (2012), 186, pp. 217 – 223, 2.159
145. Secu M, Secu CE, Sima M
Sol-gel template synthesis of luminescent glass-ceramic rods
Journal of Nanoparticle Research, (2012), 14, 4, pp. 772, 3.287
146. Sima M, Sima Mariana
Electrodeposition and anodizing of ZnMn alloy submicron wires
Digest Journal of Nanomaterials and Biostructures, (2012), 7, 3, pp. 877 – 882, 1.2
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147. Sima Mariana, Vasile E, Sima M
Preparation of nanostructured ZnO nanorods in a hydrothermal-electrochemical process
Thin Solid Films, (2012), 520, 14, pp. 4632 – 4636, 1.89
148. Simandan ID, Popescu M, Antohe S
Stabilized Langmuir layers based on silver stearate, carbon nanotubes and porphyrins additives
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Optoelectronics and Advanced Materials-Rapid Communications 6, (11-12), (2012), pp. 11641167, 0.45
149. Smaranda I, Baibarac M, Baltog I, Mevellec JY, Lefrant S
Spectroelectrochemical properties of the single walled carbon nanotubes functionalized with
polydiphenylamine doped with heteropolyanions
Journal of Solid State Chemistry, (2012), 197, pp. 352 – 360, 2.159
150. Socol G, Socol M, Stefan N, Axente E, Popescu-Pelin G, Craciun D, Duta L, Mihailescu C
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Pulsed laser deposition of transparent conductive oxide thin films on flexible substrates
Applied Surface Science, (2012), 260, pp. 42 – 46, 2.103
151. Socol G, Socol M, Sima L, Petrescu S, Enculescu M, Sima F, Miroiu M, Popescu-Pelin G,
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Combinatorial pulsed laser deposition of Ag-containing calcium phosphate coatings
Digest Journal of Nanomaterials and Biostructures, (2012), 7, 2, pp. 563 – 576 1.2
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152. Somacescu S, Dinescu A, Stanoiu A, Simion CE, Moreno JMC
Hydrothermal synthesis of ZnO-Eu2O3 binary oxide with straight strips morphology and
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Materials Letters, (2012), 89, pp. 219 – 222, 2.307
153. Stan GE, Pasuk I, Trinca LM, Galca AC, Enculescu M, Miculescu F
Tilt c axis crystallite growth of aluminium nitride films by reactive rf-magnetron sputtering
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154. Stancu M, Ruxanda G, Stanica N, Dinescu A, Nistor LC, Ciuparu D
The influence of the chemical treatment on the ferromagnetic behavior of carbon nanotubes
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155. Stanculescu F, Stanculescu A, Girtan M, Socol M, Rasoga O
Effect of the morphology on the optical and electrical properties of polycarbonate film doped
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156. Stanoiu A, Simion CE, Diamandescu L, Tarabasanu-Mihaila D, Feder M
NO2 sensing properties of Cr2O3 highlighted by work function investigations
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157. Stavarache I, Lepadatu AM, Maraloiu AV, Teodorescu VS, Ciurea ML
Structure and electrical transport in films of Ge nanoparticles embedded in SiO2 matrix
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158. Steinhoff A, Gartner PF, Matthias JF
Treatment of carrier scattering in quantum dots beyond the Boltzmann equation
Physical Review B, (2012), 85, pp. 20, 3.691
159. Stokker-Cheregi, F, AcsenteT, Enculescu I, Grisolia C, Dinescu G
Tungsten and Aluminium nanoparticles synthesized by laser ablation in liquids
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160. Tolea M, Ostahie B, Nita M, Tolea F, Aldea A
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Physical Review E, (2012), 85, pp. 3, 2.255
161. Tolea M, Moldoveanu V, Dinu IV, Tanatar B
Analysis of the phase lapse problem in closed interferometers
Physics Letters A, (2012), 376, 45, pp. 3229 – 3234, 1.632
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162. Toma O, Gheorghe L, Vlaicu AM
Synthesis and characterization of erbium lithium niobium gallium garnet
Acta Physica Polonica A, (2012), 121, 1, pp. 193 – 195, 0.444
163. Torfason K, Manolescu A, Moldoveanu V, Gudmundsson V
Excitation of collective modes in a quantum flute
Physical Review B, (2012), 85, pp. 24, 3.691
164. Ueland BG, Miclea CF, Kato Y, Ayala-Valenzuela O, McDonald RD, Okazaki R, Tobash P
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166. Ulmeanu M, Jipa F, Radu C, Enculescu M, Zamfirescu M
Large scale microstructuring on silicon surface in air and liquid by femtosecond laser pulses
Applied Surface Science, (2012), 258, 23, pp. 9314 – 9317, 2.103
167. Ungureanu F, Manea AS, Frunza L, Frunza S, Ganea CP, Cotorobai F, Diamandescu L,
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Pentylcyanobiphenyl as test molecule for the acid sites of powdered titanium(IV) oxides:
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168. Uzdin VM, Vega A, Khrenov A, Keune W, Kuncser VE, Jiang JS, Bader SD
Noncollinear Fe spin structure in (Sm-Co)/Fe exchange-spring bilayers: Layer-resolved Fe-57
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169. Vaiciulis I, Girtan M, Stanculescu A, Leonte L, Habelhames F, Antohe S
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170. Vaja (Dumitru) F, Comanescu C, Oprea O, Ficai D, Guran C
Effects of ZnO nanoparticles on the wet scrub resistance and photocatalytic properties of acrylic
coatings
Revista de Chimie, (2012), 63, 7, pp. 722 – 726, 0.599
171. Vasilache V, Apostol NG, Lungu GA, Macovei D, Teodorescy CM
Manganese-based room temperature ferromagnetism in gallium arsenide
Optoelectronics and Advanced Materials - Rapid Communications, 6, (2012), pp. 1054-1060,
0.304
172. Vasylkiv O, Borodianska H, Badica P, Grasso S, Sakka Y, Tok A, Su LT, Bosman M, Ma J
High hardness BaCb-(BxOy/BN) composites with 3D mesh-like fine grain-boundary structure by
reactive spark plasma sintering
Journal of Nanoscience And Nanotechnology, (2012), 12, 2, pp. 959 – 965, 1.563
173. Velea A, Popescu M, Sava F, Lőrinczi A, Simandan ID, Socol G, Mihailescu I N, Stefan
N, Jipa F, Zamfirescu M, Kiss A, Braic V
58
Photoexpansion and nano-lenslet formation in amorphous As2S3 thin films by 800 nm
femtosecond laser irradiation
Journal of Applied Physics, 112(3), (2012), pp. 033105-1 - 033105-4, 2.17
174. Vizireanu S, Ionita MD, Dinescu G, Enculescu I, Baibarac M, Baltog I
Post-synthesis carbon nanowalls transformation under
tetrafluoroethane and sulfur hexafluoride plasma treatments
hydrogen,
oxygen,
nitrogen
Plasma Processes and Polymers, (2012), 9, 4, pp. 363 – 370, 2.468
175. Vizireanu S, Mitu B, Luculescu CR, Nistor LC, Dinescu G
PECVD synthesis of 2D nanostructured carbon material
Surface and Coatings Technology 211, (2012), pp 2-8, 1.867
176. Yu R, Yin L, Sullivan NS, Xia JS, Huan C, Paduan-Filho A, Oliveira NF, Jr H, Stephan SA,
Miclea CF, Weickert F, Movshovich R, Mun ED, Scott BL, Zapf VS, Roscilde T
Bose glass and Mott glass of quasiparticles in a doped quantum magnet
Nature, (2012), 489, 7416, pp. 379 – 384, 36.28
177. Yu R, Miclea CF, Weickert F, Movshovich R, Paduan-Filho A, Zapf VS, Roscilde T
Quantum critical scaling at a Bose-glass/superfluid transition: Theory and experiment for a
model quantum magnet
Physical Review B, (2012), 86, pp. 13, 3.691
178. Wuttke S, Negoi A, Gheorghe NG, Kuncser VE, Kemnitz E, Parvulescu V, Coman SM
Sn-doped hydroxylated MgF2 catalysts for the fast and selective saccharification of cellulose to
glucose
Chemsuschem, (2012), 5, 9, pp. 1708 – 1711, 6.827
59
179. Zhao PH, Yan W, Yang JY, Han YL, Aldica GV, Sandu V, Badica P, Nie JC
A simple fabrication of FeSe superconductors with high upper critical field
Journal of Superconductivity and Novel Magnetism, (2012), 25, 6, pp. 1781 – 1785, 0.65
180. Zhang J, Pintilie I, Fretwurst E, Klanner R, Perrey H, Schwandt J
Study of radiation damage induced by 12 keV X-rays in MOS structures built on high-resistivity
n-type silicon
Journal of Synchrotron Radiation, (2012), 19, pp. 340 – 346, 2.726
CONFERENCE PROCEEDINGS 2012
1. Aldea A, Tolea M, Dinu IV
Zero bias anomalies in the Kondo regime of single and double quantum dots
In: Conference Proc. on Advanced Many-Body and Statistical Methods in Mesoscopic Systems
jun 27-jul 02. 2011
Advanced Many-Body and Statistical Methods in Mesoscopic Systems, (2012), 338, 012001,
10.1088/1742-6596/338/1/012001
2. Aldea A, Tolea M, Dinu IV
Fano-Kondo oscillations of the conductance and thermopower in a mesoscopic transistor
In: Proc. of: 14th International Conference on Transport in Interacting Disordered Systems
(TIDS), Acre, Israel, sep 05-08, 2011
Book Editor(s): Frydman, A, Book Series: Journal of Physics Conference Series, 376 (2012)
Article Number: 012019
3. Comorosan S, Polosan S, Popescu I, Paslaru L, Nastase A, Mitrica R, Ionescu E
Antioxidant effects induced in biological macromolecular systems by high density photons
through localized excitations
In: Proc. of The 17th European Bioenergetics Conference, Freiburg, 15 - 20 September 2012
Biochimica et Biophysica Acta-Bioenergetics, 1817 (2012) S130-S130
4.Gherendi M, Zoita VL, Craciunescu T, Johnson M.G, Pantea A, Baltog I, Edlington T,
Hellesen C, Kiptily V, Conroy S, Murari A, Popovichev S
Neutron field parameter measurements on the JET tokamak by means of super-heated fluid
detectors
60
In: Proc. of 19th Topical Conference on High-Temperature Plasma Diagnostics; May 06-10,
2012
Review of Scientific Instruments, (2012), 83, 10, 10E124, 10.1063/1.4739410; 1.367
5.Iconaru SL, Ciobanu CS, Prodan AM, Predoi D
The antimicrobial activity of fabricated iron oxide nanoparticles
In: Proc. of 22nd IUBMB Congress/37th FEBS Congress, Sep 04-09, 2012
FEBS Journal; (2012), 279, 98
6. Lefrant S, Buisson JP, Mevellec JY, Massuyeau F, Wery J, Baibarac M, Baltog I
Anti-Stokes Raman Scattering and Luminescence in Carbon Nanotube Nanostructures
In: Proc. of 11th International Conference on Frontiers of Polymers and Advanced Materials
(ICFPAM) - Emerging Technologies and Business Opportunities, Pretoria, South Africa, May
22-27, 2011
Molecular Crystals and Liquid Crystals Volume: 554, SI (2012), 111-118
7. Melinte G, Baia M, Georgescu D, Baia L, Iancu V, Diamandescu L, Popescu T, Cotet LC,
Barbu-Tudoran L, Danciu V, Simon S
The Influence of the Au Nanoparticles Dimension on the Photocatalytic Performances of TiO2Au Porous Composites
In: Proc. of: 1st International Congress on Advances in Applied Physics and Materials Science
(APMAS), Antalya, Turkey, May 12-15, 2011
Acta Physica Polonica A 121 (2012) 208-210
8. Nedelcu L, Mandache NB, Toacsan MI, Vlaicu AM, Banciu MG, Ioachim A, Gherendi F,
Luculescu CR, Nistor M
Dielectric properties of Ba(Zn1/3Ta2/3)O-3 thin films on Pt-coated Si substrates
In: Proc. of EMRS Symposium Q on Engineering of Wide Bandgap Semiconductor Materials for
Energy Saving, Nice, France, Jun 2011
Thin Solid Films, 522 (2012) 112-116
9.Nedelcu L, Busuioc C, Banciu MG, Ramer R
Ba(X1/3Ta2/3)O3 complex perovskites for microwave and millimeter wave applications
Proceedings of the 35th International Semiconductor Conference - CAS 2012, October 14-17,
Sinaia, Romania, vol. 2, pp. 303-306 (2012)
10. Niţǎ M, Marinescu DC, Ostahie B, Manolescu A, Gudmundsson V
Nonadiabatic generation of spin currents in a quantum ring with Rashba and Dresselhaus spinorbit interactions
In: Proc. of Conference on Advanced Many-Body and Statistical Methods in Mesoscopic Systems
Location: Ovidius Univ, Constanta, Romania Date: Jun 27-Jul 02 2011
Advanced Many-Body and Statistical Methods in Mesoscopic Systems Book Series: Journal of
Physics Conference Series Volume: 338(2012), Article Number: 012013
61
11. Prodan AM, Le Coustumer P, Predoi D
Evaluation of antibacterial effect of silver doped hydroxyapatite nanoparticles
In: Proc. of 22nd IUBMB Congress/37th FEBS Congress, Sep 04-09, 2012
FEBS Journal, (2012), 279, 98
12. Radu M, Iconaru SL, Predoi D, Costache M, Dinischiotu A
Assessing toxicity of two types of magnetite nanoparticles in human hepatocarcinoma cells
In: Proc. of 22nd IUBMB Congress/37th FEBS Congress, Sep 04-09, 2012
FEBS Journal, (2012), 279, 205
13. Rasoga O, Vacareanu L, Grigoras M, Enculescu M, Socol M, Stanculescu F, Ionita I,
Stanculescu A
Optical and electrical properties of arylenevinylene compounds thin films prepared by vacuum
evaporation
In: Proc. of Symposium N on Controlling and Characterising the Structure of Organic
Semiconductor Films/Spring Meeting of the European-Material-Research-Society (E-MRS),
Nice, France, May 09-13, 2011
Synthetic Metals, Volume: 161 (2012) 2612-2617
14. Sandu V, Nicolescu MS, Banciu MG, Popa S, Burdusel M
CoNb2O6 ceramic with geometric frustration
In: Proc. of 3rd International Conference on Manufacturing Science and Engineering (ICMSE
2012); Mar 27-29, 2012
Automation Equipment and Systems, PTS 1-4, 2012, 468-471, 542 – 545,
10.4028/www.scientific.net/AMR.468-471.542
15. Stanculescu F, Stanculescu A, Girtan M, Socol M, Rasoga O
Effect of the morphology on the optical and electrical properties of polycarbonate film doped
with aniline derivatives monomers
In: Proc. of Symposium N on Controlling and Characterising the Structure of Organic
Semiconductor Films/Spring Meeting of the European-Material-Research-Society (E-MRS) Nice,
France May 09-13, 2011
Synthetic Metals Volume: 161 (2012), 2589-2597
16. Stanoiu A, Simion CE, Diamandescu L, Tarabasanu-Mihaila D, Feder M
NO2 sensing properties of Cr2O3 highlighted by work function investigations
In: Proc. of EMRS Symposium Q on Engineering of Wide Bandgap Semiconductor Materials for
Energy Saving, Nice, France, Jun, 2011
Thin Solid Films, 522 (2012) 395-400
17. Toma O, Gheorghe L, Vlaicu AM
Synthesis and Characterization of Erbium Lithium Niobium Gallium Garnet
In: Proc. of 1st International Congress on Advances in Applied Physics and Materials Science
(APMAS), Antalya, Turkei, May 12-15, 2011
62
Acta Physica Polonica A Volume: 121 (2012) 193-195
CONTRIBUTED PRESENTATIONS
1.Aldica G, Miu L, Sandu V, Enculescu M, Ivan I, Batalu D, Burdusel M, Stanciuc A,
Moldovan A, Badica P
MgB2 with additions obtained by spark plasma sintering
Romanian Conference on Advanced Materials: ROCAM 2012, Brasov, Romania
28-31.08. 2012, Talk
2.Apostol NG, Lungu GA, Stoflea LE, Husanu MA, Dragoi C, Trupina, Ghica C, Pintilie L,
Teodorescu CM
Molecular beam epitaxy growth and X-ray photelectron spectroscopy analysis of Au/PZT
Heterostructures
Romanian Conference on Advanced Materials: ROCAM 2012, Brasov, Romania
28-31.08.2012, Talk
3.Apostol NG, Stoflea LF, Lungu GA, Dragoi C, Trupina L, Pintilie L, Teodorescu CM
In situ X-ray photoelectron spectroscopy analysis of Au growth on PZT(001) surfaces
9th International Conference on Physics of Advanced Materials, Iasi, Romania
20-23.09.2012, Talk
4.Apostol NG, Macovei D, Teodorescu CM
Quantification of pre-edge peaks in near-edge X-ray absorption fine structure spectroscopy of
transition metal oxides
9th International Conference on Physics of Advanced Materials, Iasi, Romania
20-23.09.2012, Talk
5.Badica P, Burdusel M, Miu L, Zhao P H, Yan W, Han Y L, Nie JC
Growth and characterization by STM of Bi2Sr0.8Ca1.8Co2Oy single crystal whiskers
Romanian Conference on Advanced Materials: ROCAM, Brasov, Romania
28-31.08.2012,Talk
6.Badica P
Superconducting composites of MgB2 with additions obtained by spark plasma sintering
E-MRS Spring Meeting & Exhibit, section HH, Moscone West Convention Center, San Francisco, USA
9-13.04.2012, (invited, session chair)
7.Badica P, Aldica G, Batalu D
MgB2 composites obtained by spark plasma sintering
20th Annual International Conference on Composites or Nano Engineering, ICCE-20, Beijing, China
22-28.07.2012, (invited, session chair)
63
8.Baibarac M, Baltog I, Magrez A, Schur D, Zaginaichenko S Yu
Single-walled carbon nanotubes functionalized with poly diphenylamine as active materials for
applications in the supercapacitors field
International Conference on Diamond and Carbon Materials, Granada, Spain
2-5.09.2012, Poster
9.Baibarac M, Baltog I, Smaranda I, Scocioreanu M, Magrez A
Nanocomposites based on carbon nanotubes and polydiphenylamine doped withheteropolyanions
for applications in the supercapacitors field
E-MRS Fall Meeting, Warsaw University of Technology,Warsaw, Poland
16-19.09.2012, Poster
10.Baibarac M, Baltog I, Velula T, Scocioreanu M, Mevellec JY, Lefrant S
Spectroelectrochemical properties of the single-walled carbon nanotubes functionalized with the
copolymer poly(3,4-ethylenedioxithiophene-co-pyrene)
9th International Conference on Physics of Advanced Materials, Iasi, Romania
20-23.09.2012, Poster
11.Baltog I, Baibarac M, Smaranda I, Lefrant S, Mevellec JY
Anti-Stokes Photoluminescence and Raman scattering in poly[(2,5-bisoctyloxy)-1,4phenylenevinylene]/single-walled carbon nanotubes composite
International Conference on Diamond and Carbon Materials, Granada, Spain
2-5.09.2012, Poster
12.Baltog I, Baibarac M, Mihut L, Smaranda I, Scocioreanu M, Magrez A
Casmir effect demonstrated by Raman Spectroscopy on Trilayer Graphene intercalated into
stiff layered structures of surfactant
E-MRS Fall Meeting, Warsaw University of Technology,Warsaw, Poland
16-19.09.2012, Poster
13.Banciu MG, Nedelcu L
Dielectric materials with special properties at extreme frequencies
Conference "Diaspora in Scientific Research and Higher Education in Romania”, Exploratory
workshop “Materials in extreme conditions – processing, properties and applications”,
Bucharest, Romania
25-28.09.2012, Talk
14.Bartha C, Patron L, Mandru I, Gingasu D, Filoti G
Thermal characterization and kinetic analysis of CoCr2O4 precursors obtained by a new route of
synthesis
Hi Temp 2012 Conference –Munich, Germany
11-13.09.2012, Poster
64
15.Besleaga C, Stan GE, Berbecaru C, Ion M, Ion L, Antohe S
Complex study of aluminium nitride thin films suitable for transparent field effect transistors
EMRS Spring Meeting, Strasbourg, France
14-18.05.2012, Talk
16.Blagoeva D T, Opschoor J, Pintsuk G, Sarbu C
Development and qualification of tungsten and tungsten alloys for fusion
20-th ANS (American Nuclear Society) topical meeting on the Technology of Fusion Energy
(TOFE-2012), Nashville, TN, USA
27-31.08.2012, (invited)
17.Braic M, Braic V, Kiss A, Plugaru N, Plugaru R
Nitrogen doped ZnO films deposited by reactive RF magnetron sputtering
13th PSE, Garmisch-Partenkirchen, Germany
10-14.09.2012, Poster
18.Braic M, Braic V, Kiss A, Plugaru N, Plugaru R
Nitrogen co-doped ZnO:Cu films grown by RF magnetron sputtering
E-MRS Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
19.Burdusel M, Aldica G, Popa S, Enculescu M, Badica P
MgB2 with addition of Bi2O3 obtained by spark plasma sintering technique
International Conference of Superconductivity and Magnetism, ICSM, Istanbul, Turkey
29.04 – 4.05.2012, Poster
20.Busuioc C, Nedelcu L, Banciu MG, Andronescu E, Jinga SI, Scarisoreanu ND, Dragoi FC
BaMg1/3Ta2/3O3 thin films obtained by PLD or Sol-Gel
Electroceramics XIII, Twente, Olanda
24-27.06.2012, Talk
21.Busuioc C, Nedelcu L, Preda N, Bartha C, Jinga SI, Banciu MG, Andronescu E
Synthesis and optical properties of lithium zinc vandate ceramic powders
ISAF ECAPD PFM , Aveiro, Portugal
9-14.07.2012, Poster
22.Busuioc C, Jinga SI, Nedelcu L, Andronescu E
Doped Ba(Zn1/3Ta2/3)O3 dielectric ceramics for microwave applications
International Conference on Advanced Materials-ROCAM , Brasov, Romania
28-31.08.2012, Poster
23.Cernea M, Dragoi C, Trinca L, Ibanescu G, Iuga A, Lowndes R, Pintilie L
Preparation and characterization of double perovskite Sr2FeMoO6 by various methods
Electroceramics XIII conference, University of Twente-Enschede, Netherlands
65
24-27.06. 2012, Poster
24.Chirila C, Ibanescu G, Hrib L, Filimon A, Negrea R, Pasuk I, Kuncser V, Pintilie I,
Pintilie L
Structural, electric and magnetic properties of Pb(Zr0.2Ti0.8)O3 – CoFe2O4 heterostructures
7th International Conference on Advanced Materials, ROCAM, Brasov, Romania
28 – 31.08.2012, Talk
25.Ciobanu CS, Iconaru SL, Coustumer P, Lafdi K, Massuyeau F, Predoi D
Complex studies on silver doped hydroxyapatite
The ASME, 11th Biennial Conference on Engineering Systems Design and Analysis (ESDA),
Nantes, France
2-4.07.2012, Talk
26.Ciobanu CS, Iconaru SL, Prodan AM, Ghita RV, Ganciu M, Chapon P, Coustumer P,
Predoi D
Preparation of silver doped hydroxyapatite nanostructure by thermal evaporation
6-th GD Conference, Paris, France
8-10.09.2012, Talk
27.Ciobanu CS, Andronescu E, Vasile B, Trusca R, Costescu A, Iconaru SL, Prodan AM,
Coustumer P, Huneau F, Motelica M, Predoi D
Novel porous hydroxyapatite for environmental application
The 3rd International Colloquium “Physics Of Materials” (PM–3), Bucharest, Romania
15-16.11.2012, Poster
28.Ciobotaru IC, Polosan S, Ciobotaru CC
Dual emitter IrQ(ppy)2 for OLED applications- synthesis and spectroscopic analysis
Sixth International Meeting on Molecular Electronics, Grenoble, France
3-7.12. 2012, Poster
29.Ciurea ML, Lepadatu AM, Stavarache I, Maraloiu AV, Palade C, Teodorescu VS
Structure and electrical characterization of GeSi nanostructured films
E-MRS 2012 Fall Meeting, Warsaw, Poland
17-21.09.2012, Poster
30.Costescu A, Ciobanu CS, Ghita RV, Ganciu M, Chapon P, Coustumer P, Barna ES, Predoi
D
Antibacterial porous hydroxyapatite nanostructures for the treatment of polluted water obtained
by thermal evaporation technique,
The 3rd International Colloquium “Physics Of Materials” (PM–3), Bucharest, Romania
15-16.11.2012, Poster
31.Costescu A, Iconaru SL, Prodan M, Ene NI, Chireac I, Ganciu M, Coustumer P, Huneau F,
Motelica M, Predoi D
66
Antibacterial studies on novel porous hydroxyapatite doped with silver ions
The 3rd International Colloquium “Physics Of Materials” (PM–3),Bucharest, Romania
15-16.11.2012, Talk
32.Cotirlan-Simioniuc C, Logofatu C, Ghita R, Negrila CC
Sensor with nanostructured surface for resonant analysis techniques
BPU, Constanta, Romania
5-7.07.2012, Poster
33.Cotirlan-Simioniuc C, Ghita R, Logofatu C, Negrila CC
Thermally grown oxides on Si(100) investigated by cavity ring-down spectroscopy
The 7-th International Conference on Advanced Materials, ROCAM, Brasov, Romania
28-31.08.2012, Poster
34.Craciun V, Socol G, Galca AC, Teodorescu C, Pearton SJ
Dependence of HfO2/IZO heterojunction band offsets on In/Zn composition
EMRS Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
35.Crisan AD, Bednarcik J, Michalik S, Crisan O
In situ monitoring of disorder-order FePt phase transformation in nanocomposite FePt based
alloys
2nd Adriatic School of Nanoscience (ASON-2), Dubrovnik, Croatia
2-7.09.2012,Talk
36.Crisan O
Surface-functionalized nanoclusters and nanoparticles
11th International Conference on Nanostructured Materials – NANO, Rhodes, Greece
26-31.08. 2012 (invited lecture)
37.Crisan O
FePt-based nanocomposite magnets
IIIrd International Conference on Superconductivity and Magnetism, ICSM, Istanbul, Turkey
29.04-4.05.2012 (invited lecture)
38.Crisan O
Nanoparticles and nanoclusters: fundamentals of synthesis and applications
2nd Adriatic School on Nanoscience (ASON-2), Dubrovnik, Croatia
2-7.09.2012 (invited lecture)
39.Crisan O
Nanoparticule si nanoclustere core-shell functionalizate la suprafata
Diaspora în Cercetarea Ştiinţifică şi Învăţământul Superior din Romania, Workshop: „Teorie si
experiment in fizica suprafetelor, interfetelor si nanoparticulelor”, Bucureşti, România.
25-28.09.2012, Talk
67
40.Dragoi C, Shi Y, Trupina L, Pasuk I, Pintilie I, Rhun G, Pintilie L
Influence of deposition method on structural and electrical properties of PZT thin films growth
on Si substrate
European Conference on Crystal Growth, University of Strathclyde, Glasgow, Scotland
17 – 20.06.2012, Poster
41.Dragoi C, Ibanescu G, Filimon A, Pintilie I, Pintilie L
Multiferroic behavior on symmetric and nonsymmetric heterostructures based on Pb(Zr0.2Ti0.8)
O3 – CoFe2O4
15th European Conference on Composite Materials, Venice, Italy
24-28.06.2012, Poster
42.Duta L, Oktar F, Stan GE, Popescu-Pelin G, Serban N, Luculescu C, Mihailescu IN
Characterization of novel doped hydroxyapatite thin films obtain by pulsed laser deposition
EMRS Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
43.Duta L, Stan GE, Socol G, Popescu AC, Miroiu FM, Mihailescu IN, Ianculescu A, Chiriac A,
Poeata I
Hydroxyapatite thin films synthesized by pulsed laser deposition and radio frequency-magnetron
sputtering onto titanium mesh implants
ROMOPTO, Bucharest, Romania
3-6.09.2012, Poster
44.Duta L, Oktar FN, Stan GE, Mihailescu IN
Novel doped hydroxyapatite thin films obtained by Pulsed Laser Deposition
4th Edition“Current trends and advanced ellipsometry and all X-ray techniques for the
characterization of TCO, BIO and other nanostructured materials” Workshop, Bucharest,
Romania
12-14.09.2012, Talk
45.Duta L, Oktar FN, Stan GE, Craciun D, Popescu-Pelin G, Serban N, Popescu AC,
Mihailescu IN
Adherent hydroxyapatite thin films synthesized by Pulsed Laser Deposition onto titanium
implants
EMRS Fall Meeting, Warsaw, Poland
17-21.09.2012, Poster
46.Enache M, Preda L, Anastasescu M, Negrila CC, Lazarescu MF, Lazarescu V
Self-assembled monolayers of L-cysteine on GaAs(100) electrodes
Third Regional Symposium on Electrochemistry: South-East Europe RSE-SEE, Bucharest,
Romania
13-17.05.2012, Talk
68
47.Enache M, Preda L, Lazarescu V, Negrila CC, Lazarescu MF
Potential-induced conformational changes in self-assembled monolayers of L-cysteine at pGaAs(100) electrodes
222nd ECS Meeting PRIME, Honolulu, SUA
7-12.10.2012, Poster
48.Enculescu I, Matei E, Florica C, Enculescu M, Kuncser V, Toimil Molares ME
Influence of electrodeposition conditions on the magnetic properties of cobalt nanowires
4th International Conference on NANO-structures SELF-Assembly (NanoSEA), in Santa
Margherita di Pula, Cagliari, Italy
25-29.06.2012, Poster
49.Enculescu I, Matei E, Florica C, Enculescu M, Toimil Molares ME
Transport properties of pure and Co doped zinc oxide nanowires
ICN+T 2012, International Conference on Nanoscience + Technology, Paris, France
23-27.07.2012, Poster
50.Enculescu I, Matei E, Florica C, Enculescu M, Toimil Molares ME
Effect of the deposition conditions on the properties of magnetic nanowires
TNT 2012- Trends in NanoTechnology Conference, Madrid, Spania
10-14.09.2012, Poster
51.Enculescu M, Matei E, Preda N, Enculescu I
Low-dimensional structures with tailored light emitting properties
E-MRS 2012 Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
52.Enculescu M, Matei E, Florica C, Preda N, Enculescu I
Emissive properties of dye-doped polymer thin films containing metallic nanostructures
4th International Conference on NANO-structures SELF-Assembly (NanoSEA), in Santa
Margherita di Pula, Cagliari, Italy
25-29.06.2012, Poster
53.Enculescu M, Matei E, Enculescu I, Trautmann C
Influence of metallic nanostructures on the optical properties of dye-doped polymer thin films,
TNT 2012- Trends in NanoTechnology Conference, Madrid, Spania.
10-14.09.2012, Poster
54.Endo K, Badica P, Arisawa S, Ikenaga N, Seto M, Saito H, Kezuka H, Endo T, Nanto H
Thin film composite heterostructures of oxide multicomponent perovskites for electronics
E-MRS Spring Meeting, section HH, San Francisco, USA
9-13.04.2012, Talk
69
55.Endo K, Badica P, Kezuka H, Arisawa S, Endo T
Growth of high temperature cuprate superconductors based heterostructures
20th Annual International Conference on Composites or Nano Engineering, ICCE-20, Beijing, China
22-28.07.2012, (invited)
56.Ene-Dobre M, Banciu MG, Nedelcu L, Busuioc C, Alexandru HV
Linear dielectric resonator antenna array based on high-K ceramics
The 8th General of Balkan Physical Union, Constanta, Romania
5-7.07.2012, Talk
57.Ene-Dobre M, Banciu MG, Nedelcu L, Busuioc C, Alexandru HV
Dielectric resonator antennas with increased directivity by using (Zr0.8Sn0.2)TiO4 ceramic
International Conference on Advanced Materials-ROCAM 2012, Brasov, Romania
28-31.08.2012, Poster
58.Feraru I, Vasiliu IC, Iordanescu R, Elisa M, Bartha C
Structural characterization of cdse-doped sol-gel silicophosphate films
6th International Conference on Materials Science and Condensed Matter Physics (MSCMP),
Kishinev – Moldova
11-14.09.2012, Poster
59.Filip LD, Pintilie I, Svensson BG
Evidence of tunneling in n-4H-SiC/SiO2 capacitors at low temperatures
9th European Conference on Silico Carbide&Related Materials (ECSCRM 2012), SaintPetersburg, Russia
2-6.09.2012, Poster
60.Filip LD, Pintilie I, Svensson BG
Evidence for resonant tunnelling from interface states in as-grown n-4H-SiC/SiO2 capacitors
7th International Conference on Advanced Materials, Brasov, Romania
28-31.08.2012, Talk
61.Filoti G
Mössbauer Spectroscopy: a powerful tool for investigation of externally induced effects
Physical Methods in Coordination and Supermolecular Chemistry- Kishinev-Moldova
24-26.10.2012, Talk
62.Florica C, Ibanescu G, Matei E, Enculescu M, Preda N, Enculescu I
Electrical properties of ZnO single nanowires contacted by FIBID and EBL
TNT 2012- Trends in NanoTechnology Conference, Madrid, Spania
10-14.09.2012, Poster
70
63.Frunza L, Preda N, Matei E, Frunza S, Zgura I, Ganea P, Cotorobai F
Complex characterization of ZnO functionalized textiles. Wetting properties as determined
by contact angle measurements
The 3nd International Colloquium on “Physics of Materials”, Bucharest, Romania
15-16.11.2012, Poster
64.Frunza L, Zgura I, Frunza S, Ganea CP, Cotorobai F
Measurements of contact angle of rough and functionalized surfaces
The 7th International Conference on Advanced Materials, ROCAM, Brasov, Romania
28-31.08. 2012, Poster
65.Galassi C, Cernea M, Baldisserri C, Ibanescu AG, Negrea R, Capiani C
Influence of synthesis route and composition on the properties of BaxSr1-xFe12O19 ceramics
European Conference on the Applications of Polar Dielectrics (ECAPD-11), Aveiro, Portugal
9-13.07.2012, Talk
66.Galatanu M, Enculescu M, Tiseanu I, Galatanu A
Materiale compozite complexe SiC-W
Diaspora în Cercetarea Ştiinţifică şi Învăţământul Superior din Romania, Workshop “Materiale
în condiţii extreme: procesare, caracterizare şi aplicaţii”, Bucureşti, România
25-28.09.2012, Talk
67.Galatanu A, Jianu AD, Galatanu M, Enculescu I
Unconventional Routes for Joining W and Steel Using FAST
International Conference of Balkan Physical Union, Constanta, Romania
8-10.07.2012, Talk
68.Galatanu M, Enculescu M, Popescu B, Tiseanu I, Craciunescu T, Galatanu A
Sintering of SiC-W nano-structured composites with enhanced thermal conductivity
International Conference of Balkan Physical Union, Constanta, Romania
8-10.07.2012, Talk
69.Galatanu M, Popescu B, Plapcianu C, Enculescu M, Galatanu A, Tiseanu I, Craciunescu
T
Direct sintering of SiC/W composites with enhanced thermal conductivity
27th SOFT Conference, Liege, Belgia
24-28.09.2012, Poster
70.Galca AC, Stan GE, Trinca LM, Pasuk I
The influence of crystallites orientation on the optical properties of poly-crystalline thin films
deposited by rf-magnetron sputtering at low temperatures
EMRS Spring Meeting, Strasbourg, France
71
14-18.05.2012, Talk
71.Galca AC, Socol G, V. Craciun
Effect of gallium concentration on the optical and electrical properties of amorphous IGZO thin
films
In: EMRS Spring Meeting, Strasbourg, France
14-18.05.2012, Talk
72.Galca AC
Transparent conductive oxides thin films: Fundamental and applicative research challenges
4th Edition“Current trends and advanced ellipsometry and all X-ray techniques for the
characterization of TCO, BIO and other nanostructured materials” Workshop, Bucharest,
Romania
12-14.09.2012, Talk
73.Galca AC, Socol G, Craciun V
Effect of gallium concentration on the optical and electrical properties of amorphous IGZO thin
films
EMRS Fall Meeting 2012, Warsaw, Poland
17-21.09.2012, Talk
74.Ganea CP, Cotorobai F, Frunza S
Electrode polarization and interfaces effects in liquid crystal systems with mobile ions: The case
of ions with different diffusion coefficients
The 3nd International Colloquium on “Physics of Materials”, Bucharest, Romania
15-16.11.2012, Poster
75.Ganea CP, Frunza L, Frunza S
Model by bipolar diffusion of the polarization effects in systems with liquid crystals and mobile
ions
The 7th International Conference on Advanced Materials, ROCAM, Brasov, Romania
28-31.08.2012, Poster
76.Gherendi M, Zoita VL, Craciunescu T, Johnson M.G, Pantea A, Baltog I, Edlington T,
Hellesen C, Kiptily V, Conroy S, Murari A, Popovichev S
Neutron field parameter measurements on the JET tokamak by means of super-heated fluid
detectors
19th Topical Conference on High-Temperature Plasma Diagnostics, Monterey, USA
06-10.05.2012, Poster
77.Ghica C, Damian R, Nistor L C, Maraloiu V A, Dragoi C, Pintilie L
72
Microstructural characterization of multilayered perovskite coatings for artificial multiferroics
15th European Microscopy Congress EMC, Manchester, United Kingdom
16-21.09.2012, Poster
78.Ghica D, Ghica C, Stan G, Stefan M
Electron paramagnetic resonance of the magnetic defects in nanostructured ZnO:Mn thin films
7th International Conference on Advanced Materials ROCAM, Brasov, Romania
28-31.08.2012, Talk
79.Girtan M, Mallet R, Stanculescu A, Leontie L, Vaciulis I, Kompitsas M, Mardare D, Antohe S
Electrical and optical properties of transparent oxide/metal/oxide multilayer films depositedon
glass and PET substrates
4th International Symposium on Transparent Conductive Materials, TCM, Crete, Greece
21-26.10.2012, Poster
80.Grecu MN, Ghica D, Vlaicu AM, Valsan S, Piticescu RR
Paramagnetic defects in hydrothermal-grown anatase TiO2 nanoparticles
Conferinta Europeana de Rezonanta Magnetica EUROMAR 12, Dublin, Irlanda
29.06-6.07.2012, Poster
81.Grecu MN, Tolea F, Constantinescu S, Ghica D, Negrea RF, Kuncser V
On the room temperature ferromagnetism in iron doped nano-TiO2 anatase phase
Conferinta Europeana de Rezonanta Magnetica EUROMAR 12, Dublin, Irlanda
29.06.-6.07.2012, Poster
82.Ibanescu G, Dragoi C, Pintilie I, Pintilie L
Comparison Between Electrical Properties of Pb(Zr,Ti)O3 and BaTiO3 Capacitors with Bottom
SrRuO3 Contact and Different Metals as Top Electrode
Conferinta Intrenationala ROCAM, Brasov, Romania
28-31.08.2012, Talk
83.Iconaru SL, Ciobanu CS, Frumosu F, Costescu A, Coustumer P, Predoi D
Structural characterization and magnetic properties of iron oxides biological polymers
International Conference on Superconductivity and Magnetism - ICSM, Istanbul, Turkey
24-28.04.2012, Poster
84.Iconaru SL, Prodan AM, Andronescu E, Barna ES, Motelica-Heino M, Sizaret S, Predoi D
Synthesis and characterization of polysaccharide – maghemite composite nanoparticles and their
antibacterial properties
Coloids and Nanomedicine, Amsterdam, Netherlands
14-17.07.2012, Poster
85.Iconaru SL, Ciobanu CS, Prodan AM, Predoi D
73
The antimicrobial activity of fabricated iron oxide nanoparticles, 22nd IUBMB Congress/37th
FEBS Congress
04-09.09. 2012, Poster
86.Iconaru SL, Ciobanu CS, Chifiriuc CM, Motelica M, Coustumer P, Ganciu M, Barna ES,
Predoi D
Antibacterial assessment of iron oxide nanoparticles obtained by coprecipitation method
The 3rd International Colloquium “Physics of Materials” (PM–3), Bucharest, Romania
15-16.11.2012, Poster
87.Kuncser V, Schinteie G, Filoti G, Birsan A, Alexandrescu R, Morjan I
Complex characterization of magnetic configurations in multiphase nanoparticle systems
SIWAN5-5th Szeged International Workshop on Advances in Nanoscience, Szeged, Hungary
24-27.10.2012
88.Kuncser V, Filoti G, Jianu A, Valeanu M, Schinteie G, Sandu SG, Palade P, Crisan O
Extreme conditions influencing magnetic properties of low dimensional systems
Diaspora în Cercetarea Ştiinţifică şi Învăţământul Superior din Romania, Workshop “Materiale
în condiţii extreme: procesare, caracterizare şi aplicaţii”, Bucureşti, România
25-28.09.2012, Talk
89.Kuncser V
Mossbauer Spectroscopy –a powerful tool for investigation of local electronic phenomena and interactions in nan
NPL, Londra, UK
10.05.2012 (invited lecture)
90.Lazarescu V, Enache M, Dobrescu G, Gartner M, Negrila CC, Lazarescu MF
Molecular self-assembling control over the surface states and field-effects at n-GaAs(100)
electrodes
222nd ECS Meeting PRIME, Honolulu, SUA
7-12.10.2012, Talk
91.Le Febvrier A, Corredores Y, Zhang L, Deputier S, Demange V, Bouquet V, Lefort R, Galca
AC, Castel X, Sauleau R, Laurent P, Tanne G, Pintilie L, Guilloux-Viry M
Croissance et caracterisations dielectriques et optiques de couches minces de Bi1 ,5-xZn1-yNb1,5O61,5x-y (BZN)
12èmes Journées de Caractérisation Microondes et Matériaux, Chambéry, France
28-30.03.2012, Poster
92.Lepadatu AM, Palade C, Slav A, Stavarache I, Iordache G, Ciurea ML, Lazanu S
Iodine irradiation induced defects in high resistivity silicon
E-MRS Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
74
93.Lepadatu AM, Stavarache I, Maraloiu AV, Palade C, Teodorescu VS, Ciurea ML
Electrical behaviour related to structure of nanostructured GeSi films annealed at 700 oC
International Semiconductor Conference, IEEE, Sinaia, Romania
15-17.10.2012, ??????
94.Lepadatu AM, Stavarache I, Palade C, Teodorescu VSand Ciurea ML
Electrical properties related to the structure of films with Ge nanoparticles embedded in SiO2
matrix
E-MRS Fall Meeting, Warsaw, Poland,
17-21.09. 2012, Poster
95.Lepadatu AM, Stavarache I, Maraloiu AV, Palade C, Teodorescu VS, Ciurea ML,
Electrical and structural properties of nanostructured GeSi films
The 3rd International Colloquium “Physics of Materials” (PM–3) Bucharest, University
Politehnica of Bucharest, Romania
15-16.11.2012, Talk
96.Le Rhun G, Yin S, Dragoi C, Trupina L, Abergel J, Vilquin B, Robach Y, Defay E, Pintilie L
Toward integration of epitaxial piezoelectric thin films on silicon substrate for MEMS
applications
Conferinta Intrenationala ROCAM, Brasov, Romania
28-31.08.2012, Talk
97.Maraloiu VA, Van Der Sanden B, Wege H, Leguellec D, Blanchin MG
Follow-up of localization and biotransformations of iron oxide MRI contrast agents used for
detection of atherosclerosis in a murine model
Colloids and Nanomedicine, Amsterdam, Netherlands
15-17.07.2012, Poster
98.Maraloiu VA, Van Der Sanden B, Wege H, Leguellec D, Teodorescu VS, Blanchin MG
Biolocalization and biotransformation of iron oxide core nanoparticles used as contrast agents for
MRI of atherosclerosis
15th European Microscopy Congress, Manchester, United Kingdom
16-21.09.2012, Poster
99.Matei E, Florica C, Enculescu M, Kuncser V, Enculescu I, Toimil-Molares ME
Control of nickel nanowires properties by electrodeposition conditions
E-MRS Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
100.Matei E, Enculescu M, Preda N, Florica C, Enculescu I
Tailoring the properties of zinc oxide nanowire arrays by pulsed electrodeposition
75
4th International Conference on NANO-structures SELF-Assembly (NanoSEA), in Santa
Margherita di Pula, Cagliari, Italy
25-29.06.2012, Poster
101.Matei E, Florica C, Kuncser V, Toimil Molares ME, Enculescu I
Effect on the deposition conditions on the properties of nickel nanowires
ICN+T 2012, International Conference on Nanoscience + Technology, Paris, France
23-27.07.2012, Poster
102.Miclea CF, Nicklas M, Mota AC, Altarawneh MM, Miclea C, Harrison N, Thompson JD,
Steglich F, Movshovich R
Low temperature enhancement of the critical current in CeCoIn5. Possible signature of magnetic
order
International Conference for Superconductivity and Magnetism, Istanbul, Turkey
28.04-4.05.2012, Talk
103.Miclea CF, Nicklas M, Mota AC, Altarawneh MM, Miclea C, Harrison N, Thompson JD,
Steglich F, Movshovich R
Low temperature enhancement of the critical current in CeCoIn5
International Conference of Magnetism and Strongly Correlated Electron Systems, Busan, Korea
8-13.07.2012, Talk
104.Miclea CT, Cioangher M, Miclea CF, Trupina L, Miclea C, Amarande L, Spanulescu S,
Faibis R
A high performance piezoceramic material for a vibration transducer for balancing of rotating
parts
35 International Semiconductor Conference, CAS Sinaia, Romania
14-17.10.2012, Talk
105.Mihailescu CN, Athanasopoulos G, Pasuk I, Luculescu C, Stan GE, Saint-Martin R,
Revcolevschi A, Giapintzakis J
Growth and characterization of SrCuO2 thin films
EMRS Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
106.Miu L, Ivan I, Miu D, Mele P, Matsumoto K, Mikheenko P, Dang VS, Crisan A
High vortex depinning temperatures in YBCO films with BZO nanorods
International Conference of Superconductivity and Magnetism, ICSM, Istanbul, J. of Supercond. and Nov. M
10.1007/s10948-012-2019-x
29.04.-04.05.2012, (invited presentation)
76
107.Nedelcu L, Busuioc C, Ganea P, Banciu MG
Broadband dielectric spectroscopy of Ba(X1/3Ta2/3)O3 complex perovskites
Electroceramics XIII, Twente, Olanda
24-27.06.2012, Poster
108.Nedelcu L, Bacsei R, Ganea CP, Banciu MG, Jinga SI, Alexandru HV
Broadband dielectric spectrosocpy of Ba1-xSrxTiO3 ferroelectric ceramics
The 8th General of Balkan Physical Union, Constanta, Romania
5-7.07.2012, Poster
109.Nedelcu L, Ganea P, Banciu MG
Ferroelectric transitions and phase diagram in barium strontium titanate
ISAF ECAPD PFM , Aveiro, Portugal
9-14.07.2012, Poster
110.Nedelcu L, Busuioc C, Banciu MG
Terahertz time-domain spectroscopy of low-loss microwave ceramics
International Conference on Advanced Materials-ROCAM, Brasov, Romania
28-31.08.2012, Poster
111.Nedelcu L, Banciu MG
Millimeter and submillimeter wave properties of dielectric materials using terahertz time-domain
spectroscopy
Conferinta "Diaspora in Cercetarea Stiintifica si Invatamantul Superior din Romania",
Workshop-ul exploratoriu “Materiale in conditii extreme – procesare, proprietati si aplicatii”,
Bucuresti, Romania
25-28.09.2012, Talk
112.Negrea RF, Ghica C, Nistor LC, Maraloiu VA, Dragoi C, Pintilie L
Analytical high-resolution transmission electron microscopy characterization of multilayered
voatings for artificial multiferroics
7th International Conference on Advanced Materials, ROCAM, Brasov, Romania
28-31.08.2012, Talk
113.Nistor SV, Nistor LC, Stefan M, Ghica D, Vlaicu I
Impurities and defects in wide band-gap ZnS(O) nanocrystals
The International Conference on Defects in Insulating Materials (ICDIM), Santa Fe (NM), USA,
24-29.06.2012 (oral plenary)
114.Nistor SV, Radu R, Stefan M, Nistor LC, Ghica D, Pintilie I
Paramagnetic radiation defects in silicon detectors for collision particle experiments
The International Conference on Defects in Insulating Materials (ICDIM), Santa Fe (NM), USA
77
24-29 .06.2012, Poster
115.Nistor SV, Stefan M, Nistor LC, Ghica D
Spying with Mn2+ ions the structure changes during the thermal decomposition of
Zn5(CO3)2(OH)6 and Zn(OH)2 into nanostructured ZnO
The 45th Annual International Meeting of the ESR group of the Royal Society of Chemistry,
Manchester, United Kingdom
25-29.04.2012, Talk
116.Palade C, Lepadatu AM, Stavarache I, Maraloiu AV, Teodorescu VS, Ciurea ML
Transport mechanisms in SiO2 films with embedded germanium nanoparticles
International Semiconductor Conference,IEEE, Sinaia, Romania
15-17.10.2012, Talk
117.Palade P
Hydrogen storage materials used as energy carrier
Advanced workshop on solar energy conversion, Magurele, Romania
21-23.05.2012, Talk
118.Pasuk I, Chirila C, Pintilie L
Selected HRXRD results obtained at NIMP on heteroepitaxial systems
4th Edition“Current trends and advanced ellipsometry and all X-ray techniques for the
characterization of TCO, BIO and other nanostructured materials” Workshop, Bucharest,
Romania
12-14.09.2012, Talk
119.Pintilie L, Ibanescu G, Dragoi C, Husanu M, Pasuk I, Damian R, Pintilie I
Effect of electrode interfaces on the macroscopic electrical properties of epitaxial Pb(Zr,Ti)O3
and BaTiO3 Films
Conferinta ECAPAD-ISAF-PFM, Aveiro, Portugalia
9-13.07.2012, Talk
120.Polosan S, Radu IC
Mechanisms of the charge transfer in IrQ(ppy)2-5Cl dual-emitter compounds
E-MRS Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
121.Polosan S, Radu IC
Organometallic materials for low energy consumption OLED devices
The 8th General Conference of Balkan Physical Union,Constanta, Romania
5-7.07.2012, Talk
78
122.Polosan S, Radu IC
Organometallic compounds and their applications
The 7th International Conference on Advaced Materials, ROCAM, Brasov, Romania
28-31.08.2012, Talk
123.Polosan S, Radu IC
Phosphorescence of Iridium based organometallic compounds in Magnetic Field
8th International Conference on Luminescent Detectors and Transformers of Ionizing Radiation LUMDETR, Halle, Germania
9-14.09.2012, Poster
124.Polosan S, Ciobotaru IC, Stoflea L
Structural characteristics of IrQ(ppy)2 organometallic compound
Sixth International Meeting on Molecular Electronics,Grenoble, France
3-7.10. 2012, Poster
125.Popescu B, Enculescu I, Palade P, Galatanu A, Jianu AD
Utilizarea metalurgiei pulberilor pentru imbinarea W cu otel
Diaspora în Cercetarea Ştiinţifică şi Învăţământul Superior din Romania, Workshop “Materiale
în condiţii extreme: procesare, caracterizare şi aplicaţii”, Bucureşti, România
25-28.09.2012, Talk
126.Popescu M, Velea A, Sava F, Lőrinczi A
Chalcogenide systems at the border of the glass formation domain: a key for understanding the
intermediate phase and switching phenomenon
18th International Symposium on Non-Oxide and New Optical Glasses (ISNOG), Saint-Malo,
France
1-5.07.2012, Poster
127.Popescu T, Dascalu G, Diamandescu L, Feder M, Caltun OF
Occurrence of the REFeO3 (RE=La, Gd, Dy) orthoferrite phases and their influence on the
magnetic and sintering properties of the CoRE0.2Fe1.8O4 system
8th BPU, The 8th General Conference of Balkan Physical Union, Constanta, Romania
5-7.07.2012, Poster
128.Popescu T, Lupu AR, Diamandescu L
Errors in the griess assay induced by opacity, adsorption and photocatalytic properties of TiO2
nanoparticles
The Annual International Conference of the Romanian Society of Biochemistry and Molecular
Biology, Bucharest, Romania
13-14.09.2012, Talk
79
129.Plugaru N
Materials modeling from first principles electronic structure
Talk presented at the Institute of Advanced Energy, Kyoto University, Japan
2.03.2012, Talk
130.Plugaru N, Plugaru R
Porous silicon models in first principles calculations
Institute of Advanced Energy, Kyoto University, Japan
9.03.2012, Talk
131.Preda N, Enculescu M, Socol M, Zgura I, Enculescu I
Polymer nanosphere array-assisted electroless deposition of ZnO rods
E-MRS Spring Meeting, , Strasbourg, France
14-18.05.2012, Poster
132.Preda N, Enculescu M, Socol M, Enculescu I
Synthesis and characterization of biocomposites based on chitosan and vinyl polymers
E-MRS Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
133.Prodan AM, Ciobanu CS, Iconaru SL, Coustumer P, Predoi D
Antibacterial activity of silver doped hydroxyapatite nanoparticles
Coloids and Nanomedicine, Amsterdam, Netherlands
14-17.07.2012, Poster
134.Prodan AM, Coustumer P, Predoi D
Evaluation of antibacterial effect of silver doped hydroxyapatite nanoparticles
22nd IUBMB Congress/37th FEBS Congress, Sevilla, Spain
04-09.09.2012, Poster
135.Prodan AM, Andronescu E, Ciobanu CS, Vasile B, Coustumer P, Predoi D
Physico-chemical and in vitro studies on iron oxide nanoparticles
The 3rd International Colloquium “Physics Of Materials” (PM–3), Bucharest, Romania
15-16.11.2012, Talk
136.Radu IC, Polosan S
Photophysical and magnetic properties of IrQ(ppy)2–5Cl for Organic Light Emitting Device
applications
E-MRS Spring Meeting, Strassbourg, France
14-18.05.2012, Poster
80
137.Radu IC, Ciobotaru CC, Polosan S
Spectroscopy and structural analysis of Iridium intermediate compound
The 8th General Conference of Balkan Physical Union, , Constanta, Romania
5-7.07.2012, Poster
138.Radu M, Iconaru SL, Predoi D, Costache M, Dinischiotu A
Assessing toxicity of two types of magnetite nanoparticles in human hepatocarcinoma cells
22nd IUBMB Congress/37th FEBS Congress, Sevilla, Spain
04-09.09.2012, Poster
139.Radu R et al
Radiation damage on n-type silicon pad diodes after electron irradiation with energies between
1.5 MeV - 15 MeV,
RESMDD12, Florence, Italia
9-12.10.2012, Talk
140.Sandu SG, Palade P, Schinteie G, Birsan A, Kuncser V
Structural aspects and magnetic properties of Fe films grown on Si substrates. Effects of
hydrogenation treatments
International Student Conference of Balkan Physical Union (ISCBPU), Constanta, Romania
10-13.07.2012, Talk
141.Sandu V, Aldica G, Ivan I, Enachescu M, Sandu E
Tritiated MgB2 superconducting ceramics
The 7th International Conference on Advanced Materials, ROCAM, Brasov, Romania
28-31.08.2012, Poster
142.Sandu V, Ivan I, Litra-Cristian P, Sandu E
Fabrication of superconducting MgB2-based nanocomposites with magnetic inclusions by spark
plasma sintering
International Conference on Advance Materials Design and Mechanics (ICAMDM), Xiamen,
China
5-7.06.2012, Poster
143.Sandu V, Nicolescu MS, Banciu MG, Ivan I
Synthesis, Thermal and Magnetic Properties of the Magnetically Frustrated CoNb2O6 Compound
International Conference on Advances in Materials Science and Engineering (AMSE) Bangkok,
Thailand
27-28.09.2012, Poster
144.Sandu V, Nicolescu MS, Banciu MG, Popa S, Burdusel M
CoNb2O6 ceramic with geometric frustration
International Conference on Manufacturing Science and Engineering (ICMSE) Xiamen, China
81
27-29.03.2012, Poster
145.Sava F, Simandan ID, Lőrinczi A, Velea A, Popescu M, Vlaicu AM, Socol G, Mihăilescu
IN, Stefan N
Light induced mixing effect in chalcogenide nanolayers
18th International Symposium on Non-Oxide and New Optical Glasses (ISNOG), Saint-Malo,
France
1-5.07.2012, Poster
146.Secu M, Secu CE, Damian R, Sima M, Dinescu M
Sol-gel template synthesis of luminescent glass-ceramic rods
The 8th International Conference on Luminescent Detectors and Transformers of Ionizing
Radiation – LUMDETR, Halle (Saale), Germany
10-14.09.2012, Poster
147.Simandan ID, Popescu M, Antohe S
Langmuir stabilized layers and UV-sensor based on silver stearate, carbon nanotubes and
porphirins additives
The 8th General Conference of Balkan Physical Union, (BPU),Constanta, Romania
5-7.07.2012, Poster
148.Slav A, Lepadatu AM, Palade C, Stavarache I, Iordache G, Ciurea ML, Lazanu S
Iodine irradiation induced defects in crystalline silicon
International Semiconductor Conference, IEEE Sinaia, Romania
15-17.10.2012, Talk
149.Socol G, Socol M, Sima LE, Luculescu CR, Enculescu M, Miroiu M, Preda N, Stanculescu
A, Sima F, Cristescu R, Petrescu SM, Mihailescu IN
Combinatorial pulsed laser deposition of calcium phosphates
European Materials Research Society-Spring Meeting, EMRS, Strasbourg, France
14-18.05.2012, Poster
150.Socol G, Socol M, Stefan N, Axente E, Pelin G, Craciun D, Duta L, Mihailescu CN,
Mihailescu IN, Stanculescu A, Visan D, Galca AC, Craciun V
CdTe/CdS thin-film solar cells fabricated by Pulsed Laser Deposition Pulsed Laser Deposition of
CdTe/CdS thin-film solar cells
EMRS Spring Meeting Conference, Strasbourg, France
14-18.05.2012, Poster
151.Socol M, Socol G, Rasoga O, Preda N, Mihailescu I, Vacareanu L, Grigoras M,
Stanculescu F, Stanculescu A
On arylenevinylene oligomers based heterostructures obtained by MAPLE for optoelectronic
applications
European Materials research Society-Spring Meeting, EMRS, Strasbourg, France
82
14-18.05.2012, Poster
152.Socol M, Preda N, Vacareanu L, Grigoras M, Socol G, Stanculescu F, Stanculescu A,
Stoicanescu M
Organic heterostructures based on arylenevinylene oligomers obtained by MAPLE
The seventh International Conference on Advanced Materials, ROCAM , Brasov, Romania
28-31.08.2012, Poster
153.Sofronie M, Crisan AD, Enculescu M, Tolea F, Valeanu M
Martensitic transformation, magnetic behaviour and magnetoelastic effect in Fe
melt-spun ribbons
Romanian Conference on Advanced Materials: ROCAM, Brasov, Romania
28-31.08.2012, Poster
70-xPd30MnX
154.Stan GE, Popa AC, Pasuk I, Galca AC, Aldica G, Ferreira JMF
Bioactive glass-based sputtered thin films: Technological algorithms for adherence improvement
EMRS Spring Meeting, Strasbourg, France
14-18.05.2012, Poster
155.Stan GE, Husanu MA, Popa AC, Pasuk I, Popescu AC, Mihailescu IN
Multi-layer haemocompatible diamond-like carbon coatings with increased functionality
EMRS Spring Meeting,Strasbourg, France
14-18.05.2012, Poster
156.Stanculescu A, Socol M, Socol G, Mihailescu IN, Grigoras M, Vacareanu L, Stanculescu F
Arylenevinylene based heterostructures on Al:ZnO/flexible substrates for photovoltaic
applications
4th International Symposium on Transparent Conductive Materials, TCM, Crete, Greece
21-26.10.2012, Talk
157.Stanculescu A, Socol M, Rasoga O, Mihailescu IN, Socol G, Stefan N, Stanculescu F
Effect of the laser deposition conditions on the properties of metal phthalocyanine based
heterostructures for photovoltaic applications
European Materials Research Society-Spring Meeting, EMRS,Strasbourg, France
14-18.05.2012, Poster
158.Stanculescu A, Socol M, Ionita I, Stanculescu F
Nonlinear optical phenomena in doped and irradiated aromatic derivatives crystals
The seventh International Conference on Advanced Materials ROCAM, Brasov, Romania
28-31.08.2012, Poster
159.Stanculescu F, Stanculescu A
Aromatic derivatives organic semiconductors
The 7th International Conference on Advanced Materials, ROCAM,Brasov, Romania
83
28-31.08.2012, Talk
160.Stanculescu F, Ionita I, Socol M, Stanculescu A
Pure and doped aromatic derivative crystals grown by Bridgman-Stockbarger method for optical
nonlinear applications
The Fourth European Conference on Crystal Growth ECCG 4, Glasgow, UK
17-20.06.2012, Poster
161.Stanculescu F, Ionita I, Socol M, Stanculescu A, Barvinschi F
Growth of pure benzil crystals from the melt by Bridgman-Stockbarger method. The effect of
irradiation on their properties
The Fourth European Conference on Crystal Growth ECCG 4, Glasgow, UK
17-20.06.2012, Poster
162.Stanculescu F, Socol M, Albu AM, Socol G, Girtan M, Stanculescu A
Optical and electrical properties of heterostructures based on maleic anhydride –aniline
derivatives monomers thin films for optoelectronic and photovoltaic applications
The seventh International Conference on Advanced Materials ROCAM, Brasov, Romania
28-31.08.2012, Poster
163.Stavarache I, Lepadatu AM, Maraloiu AV, Palade C, Teodorescu VS, Ciurea ML
Electrical behaviour of Ge nanoparticles network embedded in SiO2 matrix
E-MRS Spring Meeting, Strasbourg, France
14-18.03. 2012, Poster
164.Stavarache I, Palade C, Lepadatu AM, Maraloiu AV, Teodorescu VS, Ciurea ML
Electrical behaviour related to the structure of SiO2 films with embedded Ge nanoparticles
The 3rd International Colloquium “Physics of Materials” (PM–3) Bucharest, , University
Politehnica of Bucharest, Romania
15-16.11.2012, Talk
165.Stefan M, Nistor SV
Multifrequency EPR of Mn2+ in II-VI semiconductor nanocrystals
The 45th Annual International Meeting of the ESR group of the Royal Society of Chemistry,
Manchester, United Kingdom 25-29.03.2012, Talk
166.Teodorescu VS, Maraloiu AV,Ghica C, Scarisoreanu N, Dinescu M, A Barborica A,
Stavarache I, Ciurea M L
Pulsed laser crystallization of SiGe amorphous thin films obtained by magnetron sputtering
15th European Microscopy Congress EMC, Manchester, United Kingdom
16-21.09.2012, Poster
167.Tolea F, Crisan A, Sofronie M, Kuncser V, Valeanu M
Ferromagnetic Shape Memory Alloys prepared by melt spinning technique
84
Diaspora în Cercetarea Ştiinţifică şi Învăţământul Superior din Romania, Workshop “Materiale
în condiţii extreme: procesare, caracterizare şi aplicaţii”, Bucureşti, România
25-28.09.2012, Talk
168.Tolea F, Birsan A, Sofronie M, Kuncser V, Valeanu M
Magnetic properties of FeNiCoTi shape memory ribbons
The 7th International Conference on Advanced Materials, ROCAM, Brasov, Romania
28-31.08.2012, Poster
169.Tolea F, Sofronie M, Birsan A, Kuncser V, Valeanu M
Tunning the martensitic transformation in Ni-Fe-Co-Ga melt-spun ribbons through selective
thermal treatments
IHI TEMP Conference, Munich, Germany
11-13.09.2012, Poster
170.Trinca LM, Galca AC, Socol G, V. Craciun
Stoichiometry dependence of the optical properties of amorphous IGZO thin films
4th Edition“Current trends and advanced ellipsometry and all X-ray techniques for the
characterization of TCO, BIO and other nanostructured materials” Workshop, Bucharest,
Romania
12-14.09.2012, Talk
171.Viespe C, Nicolae I, Grigoriu C, Trupina L
Surface acoustic wave sensors coated with nanocomposite (polymer/Si nanoparticles) sensitive
layers by combined laser/spray technique
EMRS Fall Meeting Conference, Warsaw, Poland
17-21.09.2012, Poster
172.Vlaicu I D, Badea M, Olar R, Marinescu D
New iron(Iii) complexes with pentadentate schiff base ligands: synthesis, spectral, thermal and
biological characterization
7th International Conference on Advanced Materials, ROCAM, Brasov, Romania
28-31.08.2012, Talk
INVITED LECTURES
Apostol NG, Lungu GA, Costescu RM, Husanu MA, Popescu DG, Stoflea LE, Teodorescu CM
Ferromagnetic compounds stabilized on Ge(001) and Si(001) by molecular beam epitaxy
9th International Conference on Physics of Advanced Materials, Iasi, Romania
20-23.09.2012
85
Apostol NG
Reactivitate si magnetism in straturi subtiri feromagnetice depuse pe semiconductori prin epitaxie in
fascicul molecular
Exploratory Workshop WE5 Theory and experiment in surface, interface and nanoparticle physics,
Conference of Romanian Diaspora 2012, Magurele, Romania
26-27.09.2012
Badica P
Superconducting composites of MgB2 with additions obtained by spark plasma sintering
2012 MRS Spring Meeting & Exhibit, section HH,Moscone West Convention Center, San Francisco,
USA
9-13.04. 2012
Badica P, Aldica G, Batalu D
MgB2 composites obtained by spark plasma sintering
20th Annual International Conference on Composites or Nano Engineering, ICCE-20, Beijing, China
22-28.07.2012
Banciu MG, Nedelcu L
Materiale dielectrice cu proprietati deosebite la frecvente extreme
Exploratory Workshop "Materials in extreme conditions-processing, properties and applications”,
Conference of Romanian Diaspora 2012, Magurele, Romania
25-28.09.2012
Ciurea ML
Effects produced by the irradiation with heavy ions on high resistivity crystalline silicon
The 3rd International Colloquium “Physics of Materials” (PM–3)
Bucharest, University Politehnica of Bucharest, Romania
15-16.11.2012
Endo K, Badica P, Kezuka H, Arisawa S, Endo T
Growth of high temperature cuprate superconductors based heterostructures
20th Annual International Conference on Composites or Nano Engineering, ICCE-20, Beijing, China
22-28.07. 2012
Ghica C, Nistor L C, Teodorescu V S
From conventional to aberation corrected TEM in materials science
7th International Conference on Advanced Materials, ROCAM 2012, Brasov, Romania 28-31.08.2012
Ghica C
From conventional to aberration-corrected TEM in materials science - Advanced structural
investigations at NIMP
International Workshop [email protected], Trieste, Italy
11-12.12.2012
86
Ghita RV
On the passivation of GaAs surface by sulfide compounds
XI International Conference on Nanostructured Materials, August 2012, Rhodos-Greece
Section: Materials with controlled nanostructure via chemistry
26-31.08.2012
Kuncser V
Mossbauer Spectroscopy a powerful tool for investigation of local electronic phenomena and
interactions in nanomaterials
National PhysicalLaboratory (NPL), Londra, UK
DATA
Miu L, Ivan I, Miu D, Mele P, Matsumoto K, Mikheenko P, Dang VS, Crisan A
High vortex depinning temperatures in YBCO films with BZO nanorods
International Conference of Superconductivity and Magnetism, ICSM 2012, Istanbul, in J. of
Supercond. and Nov. Magn., DOI 10.1007/s10948-012-2019-x
29.04-4.05.2012
Moldoveanu V
On the cotunneling regime of interacting quantum dots
Weierstrass Institute (WIAS) Berlin
18.05.2012
Moldoveanu V
On the steady-state regime of open quantum systems,
Weierstrass Institute (WIAS) Berlin
18.05.2012
Nistor SV, Stefan M, Ghica D, Nistor LC
Core and surface localization of the activating Mn2+ ions in luminescent ZnS quantum dots
8th International Conference on Luminescent Detectors and Transformers of Ionizing Radiation,
LumDeTr 2012, Halle (Salle), Germany
10-14.09.2012
Pintilie L
Photovoltaic effect in PZT based oxide structures
International Symposium on Integrated Functionalities, ISIF 2012, Hong-Kong, China
18-21.06.2012
Pintilie L, Cernea M, Iuga A, Dragoi C, Pasuk I, Ibanescu A, Pintilie I, Trupina L, Damian R
Interfaces, structure and electrical measurements in ferroelectric thin films
COST-SIMUFER workshop, Vilnius, Lithuania
87
23-24.04.2012
Pintilie L
From bulk to nano advanced functional materials: materials science at NIMP
CERIC workshop, , Trieste, Italy
10-11.12.2012
Pintilie I
Surface and bulk radiation induced defects in Si-based sensors
1st Conference on Radiation and Dosimetry in Different Fields of Research (RAD2012), Nis,
Serbia
24-27.04.2012
PopescuM, Velea A, Sava F, Lőrinczi A,
Chalcogenide systems at the border of the glass formation domain: a key for understanding the
intermediate phase and switching phenomenon
18th International Symposium on Non-Oxide and New Optical Glasses (ISNOG - 2012), SaintMalo, France
1-5.07.2012
Popescu M, Velea A
The key properties in chalcogenide systems and their relevance on electrical switching
The 7th International Conference on Advanced Materials, ROCAM 2012, Brasov, Romania
28-31.08.2012
Popescu M, Velea A
Chalcogenide glasses for photonics
The International Conference on Advanced Materials for Photonics, Sensing and Energy
Conversion Applications (AMPSECA 2012), El-El Jadida, Maroc
5-9.12.2012
Stanculescu F, Stanculescu A,
Aromatic derivatives organic semiconductors
The 7th International Conference on Advanced Materials, ROCAM 2012, Brasov, Romania
28-31.08. 2012
Teodorescu CM
Ferromagnetic surface alloys synthesized by molecular beam epitaxy and characterized by innershell spectroscopies
Romanian Conference on Advanced Materials ROCAM 2012, Brasov (Romania),28-31.09. 2012
88
SELECTED RESULTS
Condensed Matter Physics
at Mesoscale
89
Comparative study of NBT-BTx lead-free piezoelectric materials in the form
of bulk and thin films, processed by different methods
M. Cernea, C. Dragoi, L. Trupina, I. Pintilie, L. Pintilie, A. C. Galca, L. Trinca and V.G. Aldica
in collaboration with
B. S. Vasile,
University POLITEHNICA of Bucharest, 060042, Romania
and
R. Trusca, G. Ioncea
METAV-R&D S.A., P.O. 22, Bucharest, Romania
(Na0.5Bi0.5)1−xBaxTiO3 (abbreviated as NBT-BTx) ceramics (bulk and thin films) are a promising
piezoelectric material without lead. Various methods are used to synthesis NBT-BTx with microstructural
features required for engineering these properties [1-6]. Grain size is an important microstructural
characteristic that affects piezoelectric properties. Although the piezoelectric properties are expected to
degrade with smaller grain size, the relative permittivity increases. Moreover, finer grain piezoelectric
offers two main advantages; higher mechanical strength and improved dielectric strength, if the
piezoelectric properties could be preserved. Recently, considerable research efforts have been devoted to
the preparation of NBT-BTx ceramics by various wet chemical and physical methods. Consequently, we
used sol-gel and spark plasma sintering (SPS) methods to prepare NBT-BTx bulk [1, 3-5] and sol-gel
method to prepare NBT-BTx thin films [2, 6]. For example, Fig.1(a) shows the HR-TEM image of NBTBT0.05 thin film derived from gel. The film is composed of polyhedral shaped particles, with an average
grain size of approximately 35 nm [2]. The surface of NBT-BT0.05 thin film presents a Rms of ~4.52 nm
(Fig.2(a)) and polarized nanoregions, randomly distributed at room temperature (Fig.2(b)). For
comparison, the NBT-BT0.08 thin film, prepared by as from gel precursor, shown a Rms = 2.76 nm, grains
with ferroelectric domains and better electrical characteristics than NBT-BT0.05. The dielectric
characteristics of BNT-BT0.08 thin films, measured at room temperature and 10 kHz, were: the dielectric
constant εr = 243, the loss tangent tanδ = 0.38, the remnant polarization Pr = 0.87 μC/cm2, the coercive
field Ec = 220 kV/cm, the current density = 2.7 x 10-5 A/cm2 at 100 kV/cm and piezoelectric properties
(d33eff = 100 pm/V) comparable to those of PZT thin films. These results suggest that BNT-BTx films can
be used as lead-free ferroelectric and piezoelectric material.
90
Fig.1. Cross-sectional TEM images of the BNT-BT0.05 thin film (a), corresponding HR-TEM of
nanocrystals (b) and SAED image (c)
BNT-BT.x, were x= 0.05, 0.08 and 0.11, bulk ceramics were prepared from gel powders and sintered by
SPS technique in order to evaluate the influence of grain size and concentration x on the electric
properties of BNT-BT.x ceramics. The SEM micrographs of the BNT-BT.x ceramics show dense
microstructures with grains size of 60-80 nm (Fig.3). The best densification was obtained for BNT-BT0.08
ceramic (relative density (ρ/ρtheor), =99.6 %). Like the classic sintered BNT-BTx ceramics, these ceramics
densified by SPS show rhombohedral-tetragonal morphotropic phase boundary (MPB) for x=0.08, were
the dielectric and piezoelectric properties are substantially improved [4].
(a)
(b)
Fig.2. Atomic force microscopy image (AFM) (a) and PFM image of BNT-BT0.05 thin film (b)
91
Fig.3. SEM images of fracture surface for BNT-BT0.08 ceramic obtained by SPS
The SPS BNT-BTx ceramics show a pronounced diffuse phase transition associated with the grain size
and the heterogeneity in microstructure and composition. The diffusive factor increases as increasing
BaTiO3 concentration (Fig.4). The permittivity of BNT-BT0.08 is higher (εr =2090, at 100 kHz) than that
for x=0.05 (εr =1350) and x=0.11 (εr =1800).
5
200
105(1/ε - 1/εmax)
4
δ (oC)
175
150
3
x (mol %)
6
8
10
2
1
0
0,0
0,2
0,4
0,6
0,8
(T-Tm)2/2εmax (oC2)
1,0
Fig.4. The plots of (1/εr −1/εr max) as function of (T−Tm)2/2εr max for the BNT-BTx pellets obtained by SPS.
The inset shows the composition dependence of diffusive factor
The electrical properties of these ceramics are influenced by grains size, oxygen deficiency and
nonuniform internal stresses due to these oxygen deficiencies. BNT-BTx ceramics sintered by SPS seem
to be good ceramic resonators with high mechanical quality factor (Q).
This work was carried out in the frame of the project 72-153-MPPC, funded by the Romanian Ministry of
Education and Research.
92
References
[1] M. Cernea, B. S. Vasile, C. Capiani, A. Ioncea, C. Galassi, J. Eur. Ceram. Soc., 32 (2012) 133-139.
[2] M. Cernea, L. Trupina, C. Dragoi, B. S. Vasile, R. Trusca, J. Alloy. Compd., 515 (2012) 166-170.
[3] M. Cernea, F. Fochi, G. V. Aldica, B. S. Vasile, R. Trusca, C. Galassi, J. Mater. Sci., 47 (2012) 36693673.
[4] M. Cernea, G. Poli, G. V. Aldica, C. Berbecaru, B. S. Vasile, C. Galassi, Curr. Appl. Phys., 12 (2012)
1100-1105.
[5] M. Cernea, C. Galassi, B. S. Vasile, C. Capiani, C. Berbecaru, I. Pintilie, L. Pintilie, J. Eur. Ceram.
Soc., 32 (2012) 2389-2397.
[6] M. Cernea, L. Trupina, C. Dragoi, A. C. Galca, L. Trinca, J. Mater. Sci., 47 [19] (2012) 6966-6971.
93
Spectroscopic Ellipsometry: a useful non-destructive technique to probe the
physical parameters of thin films
A. C. Galca, G.E. Stan, L.M. Trinca, C.C. Negrila, L.C. Nistor, M. Enculescu, L. Pintilie, M.
Cernea, L. Trupina, C. Dragoi, C. Besleaga
in collaboration with
F. Miculescu
Politehnica University of Bucharest, Romania
L. Ion, S. Antohe
University of Bucharest, Romania
G. Socol, V. Craciun
National Institute for Lasers, Plasma and Radiation Physics, Magurele, Romania
A. Le Febvrier, Y. Corredores, S. Deputier, V. Bouquet, V. Demange, X. Castel, R. Saleau, R. Lefort, M.
Guilloux-Viry
Universite de Rennes 1, France
L. Y. Zhang, G. Tanne
Universite de Bretagne Occidentale, Brest, France
Spectroscopic ellipsometry is a unique characterization technique which measures the change in
polarization of a light-probe reflected from a sample. The measurements are relatively fast, low cost and
non-destructive.
By fitting the ellipsometry data with an adequate optical model, there are determined in the first
step the thicknesses and the complex dielectric function (also expressed as refractive index and extinction
coefficient) of the sample (usually a thin film). Using results for complementary techniques, advanced
optical models can be developed in order to determine fast and non-destructively physical properties such
as: degree of crystallinity, crystallites size and orientation, porosity, composition and electrical properties.
Inspection by ellipsometry of thin aluminum nitride (AlN) films obtained by rf-magnetron
sputtering at different deposition times, led to the conclusion that the films have a slightly dispersed
orientation of [002] crystallites axis during the initial growth stages, whereas the orientation verges the
normal to the surface after the growing process stabilizes [1]. Diffraction studies (X-ray diffraction and
Selected Area Electron Diffraction) confirmed the ellipsometry results.
94
Based on the slight optical anisotropy of the AlN, the birefringence was determined by ellipsometry
in the case of thick AlN films (~1 μm) (Fig.1). The crystallites tilt angle versus distance from the centre of
the interference rings show a similar profile, and further correlations can be made [2].
Fig.1 Birefringence profile of the AlN thick film.
The tendency of poly-crystalline thin films deposited at low temperature to form a double-layerlike structure, each of them with distinct features, was observed also in the case of zinc oxide (ZnO) thin
films [3].
Thickness results obtained from simulations of X-ray Reflectivity and Spectroscopic Ellipsometry
data on InGaZnO thin films were very similar [4]. The dependence of density on stoichiometry resembles
the corresponding dependence of the refractive index in the transparency range (Fig.2). This dependence
between the refractive index and the mass density breaks down in the case of a weak absorbing
compound.
Fig.2 Thin InZnO film refractive index obtained by ellipsometry and the mass density derived from X-ray
reflectivity.
95
The influence of barium titanate (BT) concentration on the dielectric functions of (Na0.5Bi0.5)1xBaxTiO3 (BNT–BTx) thin films, with x = 0.05, 0.08, and 0.11 thin films was also investigated [5]. It is
observed that the high frequency dielectric function ε∞ decreases with increasing of BT concentration.
The same dependence is observed also for dielectric function (ε1), electrical measured at 100 kHz.
The refractive index of the Bi1.5-xZn0.92-yNb1.5O6.92-δ thin films grown by PLD on R-plane sapphire
and LaAlO3 substrates, shows a quasi-linear dependence on grain size. A strong correlation between the
characteristics measured by spectroscopic ellipsometry on bare thin films (n in the optical range) and on
coplanar devices in the microwave range (εr at 10 GHz) was evidenced (Fig.3). Although, the dependence
of the refractive index on grain size cannot be generalized to other thin films and/or other deposition
processes, unexpected optical properties – grain size relationship might be understandable according to
this work [6].
Fig.3 Refractive index and dielectric constant of
BZN films versus grain size.
NIMP researchers acknowledge financial support from PNII 72-153/2008, 12-101/2008, PCCE ID
76, RU-TE-2011-3-0016 and Core Program PN09-45.
References
[1] A.C. Galca, G.E. Stan, L.M. Trinca, C.C. Negrila, L.C. Nistor, Thin Solid Films 524 2012, 328333 doi:10.1016/j.tsf.2012.10.015
[2] G.E. Stan, I. Pasuk, L.M. Trinca, A.C. Galca, M. Enculescu, F. Miculescu
Dig. J. Nanomater. Biostruct. 7 (1) 2012, 41-50
http://www.chalcogen.infim.ro/41_Stan.pdf
96
[5]. C. Besleaga, G.E. Stan, A.C. Galca, L. Ion, S. Antohe, Appl. Surf. Sci. 258 (22) 2012, 88198824 doi:10.1016/j.apsusc.2012.05.097
[4]. A.C. Galca, G. Socol, V. Craciun
Thin Solid Films 520 (14) 2012, 4722-4725 doi:10.1016/j.tsf.2011.10.194
[5].M. Cernea, L. Trupina, C. Dragoi, A.C. Galca, L. Trinca, J. Mater. Sci. 47 (19) 2012, 69666971 doi:10.1007/s10853-012-6646-1
[6] A. Le Febvrier, A.C. Galca, Y. Corredores, S. Députier, V. Bouquet, V. Demange, X. Castel, R.
Sauleau, R. Lefort, Ly. Zhang, G. Tanné, L. Pintilie, M. Guilloux-Viry,
ACS Appl. Mat. Interf. 4 (10) 2012, 5227- 5233 doi:10.1021/am301152r
Organometallic compounds:
synthesis and characterization
S. Polosan, I.C.Radu (Ciobotaru), I. Enculescu
in collaboration with
H. Iovu
University POLITEHNICA of Bucharest, Romania
To obtain white light phosphores-cence, organometallic compounds with different emissions
must be mixed and the best way is to create mixed-ligands complexes which gives different color from
each ligand.
Recently, we purposed another Ir(III) complex (5-chloro-8-hydroxy-quinolinat) bis(2phenylpyridyl) iridium (IrQ(ppy)2-5Cl) which combine the properties of the red phosphorescence given
by quinoline (Q) ligand and the green phosphorescence originated from phenylpyridine [1].
Mixed-ligands of IrQ(ppy)2–5Cl was synthesized by the reaction of substituted 8hydroxyquinoline with the diiridiumcomplex tetrakis (2-phenylpyridyl) -μ-(dichloro) diiridium
([(C^N)2Ir-μ-Cl]2). For the absorption measurements, neat film and 5 wt.% of mer–IrQ(ppy)2–5Cl,
dispersed in polystyrene, were deposited on the quartz substrate.
The absorption spectrum (figure 1) can be divided in two parts: one, between 700 to 300 nm
assigned to the metal-to-ligand charge transfers and the second, between 300 to 200 nm for the intraligand
97
transitions. Starting with the low energy peaks, the first peak measured at 625 nm (1.982 eV), can be
assigned to the first triplet state arising from the quinoline ligand. The absorption bands at 380 and 285
nm were atributed to the metal-to-ligand charge transfer singlet state (1MLCT) and ligand centered singlet
state (1LC), in the ppy ligand while the 515 nm (2.4 eV) emission band to the transition from the triplet
3
MLCT to the ground state.
Figure 1
The red phosphorescence band is due to the transition from the spin-triplet state to the singlet
ground state appearing at 666 nm in IrQ(ppy)2-5Cl.
The Magnetic Circular Dichroism (MCD) peaks appear more intense compared with the absorption
spectrum (figure 2). The peaks between 300-500 nm are assigned to the Metal-to-Ligand Charge Transfer
(MLCT), while below 300 nm are assigned to the intraligand π→π* transitions.
Time-dependent density functional theory (TD-DFT) calculation provides useful parameters for the
experimental measure-ments, the results of calculation being in good agreement with the observed facts.
The highest occupied orbitals in the case of IrQ(ppy)2-5Cl are Ir(5d) in character, with a non-equal
distribution of the charge transfer between the ppy and quinoline ligands (figure 3).
Figure 2
98
This fact leads to a decreasing of the phosphorescence provided by the charge transfer to the ppy
ligand, but also the appearing of the red emission as a result of the charge transfer to the quinoline ligand.
Figure 3
The hybridization between Ir 5d orbitals and π ligand orbitals shows strong metallic character with
phenylpyridine orbitals (66% and 43 %) and weak metallic character with quinoline ligand (16.8%). This
fact can explain weak red phosphorescence intensity in the emission spectra [2].
The phosphorescence mechanism of the mer-Alq3 powder, together with the structural changes which
appears during thermal annealing, were detailed [3].
Cathodoluminescence image (figure 4) was compared with the secondary electron image, showing a
slightly charge of the mer-Alq3 surface, specific for semiconductors.
Figure 4
The cathodoluminescence spectrum (figure 5) shows similar features with the photoluminescence
spectrum and, at the long wavelengths, exhibits a small emission associated with triplet phosphorescence.
99
Figure 5
The annealing procedure at different times, below the first phase transition temperature (295oC),
induces the growing of the nanocrystals along the axis perpendicular to the (01-1) plane.
This work was carried out in the frame of the Nucleus Program Contract number PN-45 and
Romanian National Authority for Scientific Research, CNCS-UEFISCDI, project number PN-II-ID-PCE2011-3-0620.
References:
[1] S. Polosan, I.C. Radu, T. Tsuboi, J. Lum.132(4), 2012, 998-100.
[2] S. Polosan, I.C. Radu, J. Nano.& Nanotech. (2013) (accepted, September 2012).
[3] I.C. Radu, S. Polosan, I. Enculescu, H. Iovu, Optical Materials, 35(2), 2012, 268-273.
Bose-glass/superfluid transition in a quantum magnet
C.F. Miclea1, R. Yu2, L. Yin3, N. S. Sullivan3, J. S. Xia3, C. Huan3, A. Paduan-Filho4,N. F. Oliveira Jr.4, S.
Haas5, A. Steppke6, F. Weickert7 ,R. Movshovich7, Eun-Deok Mun7, B. L. Scott7, V. S. Zapf7, and T.
Roscilde8
1
National Institute for Materials Physics, Bucharest-Magurele, Romania
2
Department of Physics & Astronomy, Rice University, Houston, USA
100
3
Department of Physics and Nat. High Magnetic Field Lab., University of Florida, Gainesville, USA
4
Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, Brasil
5
Department of Physics and Astronomy, University of Southern California, Los Angeles, USA
6
Max-Planck Institute for Chemical Physics of Solids, Dresden, Germany
7
Condensed Matter and Magnet Science, Los Alamos National Lab, NM, USA
8
Laboratoire de Physique, Ecole Normale Superieure de Lyon, Lyon, France
Bose-Einstein condensation (BEC) and superfluidity are well known quantum manifestations of bosonic
systems at low temperatures and they have been experimentally established in a large variety of systems.
However, when present, disorder precludes the condensation in the case of interacting bosons leading to a
special phase called Bose-glass (BG). This state breaks no additional symmetry and has not finite energy
gap in the spectrum, therefore making it very elusive to experimental confirmation so far. Despite more
than two decades of theoretical work, many of the aspects of the physics of interacting quantum fluids in
Fig. 1: The phase diagram of Br-doped DTN
from specific heat susceptibility, and QMC. The
lilac regions represent the magnitude of the
spin gap in the Mott insulating (MI) phase
Fig. 2: Temperature dependence of the specific
heat in different magnetic fields
a disordered environment remain unsettled.
In our work we investigate the quantum phase transition
(QPT) from a magnetic Bose Glass state to magnetic Bose-Einstein condensate in a quantum magnet
NiCl2·4SC(NH2)2 (dichlorotetrakis-thiourea-Nickel, DTN) doped with Br on the Cl site at a concentration
x = 0.08.
In the pure DTN compound, with S=1, extra bosons can be injected into the Bose fluid of magnetic
quasiparticles by applying an external magnetic field leading, above a critical value of the field, to a
Bose-Einstein condensation [1]. The Br doping induces, in a controlled fashion, randomness of bosons
hopping and interactions strengths.
101
In the temperature-magnetic field phase diagram (Fig. 1) we observed two extended Bose glass
Fig. 3: Scaling of Tc with the distance from the
critical fields. The dashed line is a fit to a|HHc1|2/3. The solid line is a fit to b|H-Hc1|ϕ with the
resulting ϕ indicated in the figure (a and b are
fitting parameters). The leftmost panels show the
AC susceptibility data, and the rightmost ones the
the QMC simulations (from Ref [2]).
regions. The lack of a gap in the spectrum is revealed by a finite, uniform susceptibility and by a nonexponential low temperature dependence of the specific heat. As the magnetic field goes to zero, the
gapless nature is retained while the susceptibility vanishes indicating that the system enters a Mott glass
(MG) state.
At very low temperatures the external magnetic field at a critical value of Hc1 = 1.07 T drives the
system into a BEC state. This phase transition is clearly visible in the susceptibility and magnetization in
field sweeping measurements at fixed temperatures as a step-like feature corresponding to the critical
field [2]. The phase boundary is also revealed by a sharp anomaly in the temperature dependence of the
specific heat at fixed external magnetic fields (Fig. 2). For temperatures below the anomaly the specific
heat has a T3 behavior as expected for a 3D long range XY antiferromagnetic order. At low temperatures
and above a critical magnetic field Hc2 = 12.16 T the system recovers a BG ground state.
The behavior of the Br-DTM is very different from the pure system. The undoped DTM adopts
outside the BEC region a Mott insulator ground state with a large spin gap Δ reflected by an exponential
temperature dependence of the specific heat and vanishing susceptibility in the low temperature limit. In
contrast, in the Br-DTM sample the susceptibility vanishes only around 17 T well above Hc2. Below Hc1
the and down to zero field the non-exponential temperature dependence of the specific heat indicate that
102
the system is gapless. The Bose glass phase extends down to zero field, where it acquires the special
nature of an incompressible (but still gapless) Mott glass, due to the commensurate bosonic filling.
The phase diagram in Br-DTN can be modeled using large-scale Quantum Monte Carlo (QMC)
simulations; we assume that Br doping distorts locally the lattice and affects the super exchange paths
associated with the antiferromagnetic coupling for bonds along the c-axis [2]. The agreement between the
experiment and model is excellent (Fig. 1).
The critical temperature, Tc of the BEC condensation for H ≥ Hc1 scales with the magnetic field as
Tc ~ |H-Hc1|ϕ. In the pure DTM ϕ is found to be 2/3. In the doped case, both experimental and theoretical
model reveal an exponent ϕ ~ 1.1 which seems to be an universal characteristic of disordered bosons (Fig.
3). This exponent appears to cross over to the pure-system value of 2/3 at sufficiently high temperature,
marking the crossover from condensation from a highly inhomogeneous BEC to condensation into a more
conventional BEC.
We have also investigated the low temperature thermodynamics close to the quantum critical points
in Br-DTN and the power laws for specific heat and magnetization have been determined [3].
In conclusion we are able to reveal for the first time the unconventional nature of the Bose-glass
phase - a gapless bosonic insulator. We investigate quantitatively the thermodynamics of such a system
and reveal a novel universal exponent governing the scaling of the critical temperature. Our results for the
low temperature power laws as well as the scaling exponent are incompatible with the conventional
crossover-scaling Ansatz proposed by Fisher et al. [4].
We acknowledge support from UEFISCDI, grant PN-II-ID-PCE-2011-3-1028.
References
1.
2.
3.
4.
Yin, L., Xia, J. S., Zapf, V. S., Sullivan, N. S., and Paduan-Filho, A., , Phys. Rev. Lett. 101, 187205 (2008).
R. Yu, L. Yin, N. S. Sullivan, J. S. Xia, C. Huan, A. Paduan-Filho, N. F. Oliveira Jr, S. Haas, A. Steppke, C. F. Miclea,
F. Weickert, R. Movshovich,
Eun-Deok Mun, B. L. Scott, V. S. Zapf, and T. Roscilde, Nature 489, 379 (2012).
R. Yu, C. F. Miclea, F. Weickert, R. Movshovich, A. Paduan-Filho, Vivien S. Zapf, and Tommaso Roscilde, Phys. Rev. B
86, 134421 (2012).
M. P. A. Fisher, P. B. Weichman, G. Grinstein, and D. S. Fisher, Phys. Rev. B 40, 546 (1989).
Enhancement of critical current density and irreversibility field
by Te or TeO2 addition to MgB2 bulk processed
by spark plasma sintering
G. Aldica, S. Popa, M. Enculescu, P. Badica
MgB2 is a superconducting material [1] with great potential for a range of applications. Different
additions to MgB2 provide functional characteristics at practical levels, regarding both the critical current
103
density, Jc, and the magnetic irreversibility field, Hirr. Successful additions reported in the literature that
enhance the performance of MgB2 are mostly various carbon-containing compounds or substances (e.g.
[2,3]). The search for other efficient additions is of great interest. At the same time, bulk MgB2 materials
need to have a high density and a controlled microstructure composed of fine particles, a certain type of
grain boundaries and defects. To attain a high bulk density, one can use the unconventional method of
spark plasma sintering (SPS) [3,4,5]. This method uses a pulsed current, leading to high heating rates.
This is effective at suppressing particle growth. Due to the pulsed current, the occurrence of non-thermal
processes, although still under debate [6], can produce special morphologies, grain boundaries and
defects, all of them influencing functional characteristics.
In this work we investigated the application of ex situ SPS on mixtures of MgB2 and chalcogenidebased powders such as α-TeO2 and Te metal. These additions melt at the relatively low temperatures of
733 and 449 °C, respectively. It is expected that a combination of suitable SPS conditions and the melting
behavior of the Te-based additions can produce a high-density MgB2 composite superconductor with
improved functional properties. We show enhancement of the critical current density, Jc, and of the
irreversibility field, Hirr, for samples with Te-based additions.
The results of the sample characterization are presented in Figs 1–4. The key results are that added
samples with xTeO2 = 0.005, 0.01 and xTe = 0.01 show superior Jc at high fields and at 5–20 K (Fig. 1, only
at 5 K). The most notable enhancement is at low temperatures. At 5 K and 8 T, the Jc(H) curve of the
sample with xTe = 0.01 shows no accelerated decrease as for the other samples and Jc(5 K, 8 T) = 1.8 103
Acm-2.
6
10
2
jc (A/cm )
5K
104
b
c
d
e
f
g
h
102
100
0
2
4
6
8
µ0H (T)
Fig. 1. Magnetic field H dependence of the critical current density Jc for all bulk samples.
Samples are: (a) raw powder; (b) pristine; (c–e) xTeO2 = 0.005, 0.01, 0.03; (f–h) xTe = 0.005, 0.01, 0.03.
104
10
b
c
d
e
f
g
h
µ0Hirr(T)
8
6
4
2
0
100 A/cm2
0
10
20
30
40
T (K)
Fig. 2. Irreversibility field vs. temperature (100 A cm-2 criterion).
Furthermore, all added samples, except for the sample xTe = 0.03, have shown a higher Hirr at 5 K than for
the pristine sample (Fig. 2). The optimum concentrations are xTeO2 and xTe = 0.01 and the best sample is
obtained for xTe = 0.01.
1
8 h
8
(110)
XRD patterns (Fig. 3) indicate approximately constant lattice parameters of MgB2 from the
samples with Te-based additions.
Intensity (a.u.)
g
6 f
6
444
4
4
444
e
4
4
d
c
2
b
a
0
20
3
32 3 2
1
1
30
2
1
40
50
2θ (degrees)
1 1
1
60
2
0
70 59
60
61
2θ (°)
a)
b)
Fig. 3. (a) X-ray diffraction patterns for all samples. Phase notation is: MgB2 (1), MgO (2), MgB4 (3) and
MgTe (4). (b) Detail of the (110)
peak.
105
The result suggests that Te substitution effects are small, if any. XRD data analysis is supported by
the magnetization curves, m(T), shown in Figure 4. The onset critical temperature, Tc, has a small
variation between 38.2 and 38.8 K, suggesting that Te substitutions in MgB2 are limited, if any.
0
m(T)/m(5 K)
-0.2
-0.4
a
b
c
d
e
f
g
h
-0.6
-0.8
-1.0
36
µ0Hdc = 0.01 T
37
38
39
T (K)
Fig. 4. Normalized magnetization vs. temperature for an applied magnetic field µ0Hdc = 0.01 T.
Zero-field-cooling transitions into superconducting state are sharp and without steps, are shifting in
an approximately parallel manner, and the saturation magnetization is attained for all the samples around
36 K.
Data suggest that Te substitution effects, if any, are not significant, and that pinning, which is
efficient for added samples at low and high temperatures and at high fields, was controlled by
“composite” effects. Among the “composite” effects, we note the decrease in the MgB2 particle size. This
presumably leads to more grain boundaries in the volume unit that may be beneficial for improving the
pinning. A second effect is formation of impurity phases MgO, MgB4 and MgTe. For the samples with
the optimum amount of addition, x = 0.01, the crystallite size of these phases is in the range of tens of
nanometers, and is the smallest among all samples. The impurity nanophases can be themself pinning
centers or, more likely, they can influence the morphology, defects or local compositional details
important for pinning.
The authors acknowledge financial support from Romanian projects “Nucleu”-PN09-450103 and
Idei Complexe 9/2010.
References
[1] Nagamatsu N, Nakagawa N, Muranaka T, Zenitani Y, Akimitsu J 2001 Nature 410 63
106
[2] Dou S X, Soltanian S, Horvat J, Wang X L, Zhou S H, Ionescu M, Liu H K, Munroe P, Tomsic M
2002 Appl. Phys. Lett. 81 3419
[3] Miu L, Aldica G, Badica P, Ivan I, Miu D, Jakob G 2010 Supercond. Sci. Technol. 23 095002
[4] Larbalestier D C et al. 2001 Nature 410 186
[5] Sandu V, Aldica G, Badica P, Groza J R, Nita P 2007 Supercond. Sci. Technol. 20 1
[6] Lee S Y, Yoo S I, Kim Y W, Hwang N M, Kim D Y 2003 J. Am. Ceram. Soc. 86 1800
[7] Groza J R, Zavaliangos A 2000 Mater. Sci. Eng. A 287 2.
Theoretical predictions of half metallic state and specific magnetic properties
in new intermetallic compounds
A. Birsan, P. Palade, V. Kuncser
Heusler compounds represent nowadays, one of the most fascinating classes of modern magnetic
materials. With a large variety of physical properties, due to their chemical flexibility and specific crystal
structure, these remarkable materials promise a wide range of applications, in spintronics, spin torque
devices, superconductors, topological insulators or thermoelectric materials. The large family of magnetoelectrical Heusler compounds is characterized by half-metallic properties. The electronic structure
studied within the framework of density functional theory, plays an important role for the determination
of magnetic properties and the prediction of half-metallic materials. Based on the comprehensive
theoretical study, the spin-polarization electronic structures and magnetic properties of the new full
Heusler compounds, Ti2CoSn and Ti2CoSi were analysed.
Fig.1. The unit cell structure of Ti2CoSn or Ti2CoSi compound.
The structure of Hg2CuTi prototype was used to define the unit cell of half-metallic Heusler compounds
analyzed (Fig.1.). These materials are hybrids between semiconductors and metals (Fig.2). At equilibrium
107
lattice constants, determined by geometrical volume optimizations, Ti2CoSn and Ti2CoSi Heusler
compounds provide a fully spin polarized current due to metallic nature for electrons of one spin
orientation and semiconducting behavior for electrons with opposite spin orientation.
Fig.2. The spin-resolved total densities of states calculated at equilibrium lattice constants for (A) Ti2CoSn
and (B) Ti2CoSi.
Both Ti2-based Heusler compounds studied, present half-metallic ferromagnetism, with surprisingly,
highest spin magnetic moments coming from Ti atoms which natively do not have magnetic properties.
Moreover, the influence of different neighborhood determines Ti atoms to have dissimilar magnetic
moments.
In spite of above mentioned similarities Ti2CoSn and Ti2CoSi Heusler compounds, the potential
fields of applications are rather different. Suitable for future application in magneto-electronics and
spintronics, Ti2CoSn presents 100% spin polarization and a total magnetic moment of 3µB for a lattice
parameter, ranging from 6.193 to 6.884 Å with an optimized lattice constant of 6.34 Å (Fig.3.).
According to theoretical calculations, in the case of the half-metallic Heusler compound Ti2CoSi, the
total magnetic moment is constant and equal to 3 µB for a lattice constant higher than 5.941 Å. Therefore,
apart from spintronics, from application’s point of view, Ti2CoSi compound is predicted to be suitable as
pressure sensitive material, because of transition from half-metal to metal obtained at 4% compression of
optimized volume. Hence, Ti2CoSi compound presents 100% spin polarization above the critical
transition point and this starts decreasing while the half metallic character is spoiled, as illustrated in
Fig.3.
108
Fig.3. (Color line) The position of highest occupied states from valence band (VB) and the lowest
unoccupied states from conduction band (CB) of total DOSs for Ti2CoSn and Ti2CoSi, as function of lattice
parameter (minority spin channel).
The band structure of Ti2CoSn and Ti2CoSi compound at equilibrium geometry is exhibited in Fig.
4. In the left panel are plotted the metallic intersections of Fermi levels from majority spin channels (spinup), while in the right panels, the band gaps from minority spin channels (spin-down). The energy gap in
Ti2CoSn compound is clearly formed due to Ti–Ti hybridization, splitting d states of Ti atoms, which are
located in the two different Wyckoff positions in the minority spin channel. The 3d orbitals of Co are
fully occupied and form a weak covalent interaction with Ti 3d orbitals.
109
Fig.4. (Color line) The band structures of Ti2CoSn and Ti2CoSi, respectively, for geometrically optimized volumes.
The band gap of Ti2CoSi is an indirect one, calculated between the energy from the highest
occupied states from valence band at the G point (0.613eV) which belong to triple degenerated
states Ti(4c) dt2g and the lowest unoccupied states from conduction band, at the L point
(0.039eV), the double degenerated states deg , with a strong Co character, in the minority spin
channel.
Finally, it should be pointed out, that these remarkable results will strengthen the interest in
Ti2CoSn and Ti2CoSi Heusler compounds as promising materials for spintronics and magnetoelectronics
applications.
References
[1] A. Birsan, P. Palade, V. Kuncser, Solid State Commun. 152 (24) 2147 (2012)
[2] A. Birsan, P. Palade, V. Kuncser, J.Magn. Magn. Mater 331 109 (2013)
110
Effects produced by iodine irradiation on high resistivity silicon
S. Lazanu, A. Slav, A.M. Lepadatu, I. Stavarache, C.Palade,
G. Iordache , M. L.Ciurea
The effects of irradiation with iodine ions on high resistivity Si were studied.
Float zone (100) Si wafers with 3 ± 0.5O off orientation, of n-type, doped with P, with resistivity
higher than 8000 Ωcm, were irradiated at the Uppsala tandem accelerator, with 127I6+ ions with the kinetic
energy of 28 MeV, at a fluence of (5±0.5)×1011 ions/cm2. The iodine ions, which are much heavier than
Si, are stopped into the Si target.
The results obtained from the simulation of the distribution of iodine ions stopped in the wafer using
the Monte Carlo Crystal-transport and range of ions in matter code [1] indicate that the majority of the
ions are found in a layer of less 2 µm thickness located at 8 µm depth from the irradiated Si surface. The
interaction between the incoming ions and silicon atoms produces recoils down to 13 µm depth.
The recoils go to interstitial positions, produce primary defects, vacancies and in-terstitials, which
diffuse deeper than 13 µm. They interact between themselves and with the impurities (O, C, P) in the
wafer producing point defects as V2, VP, CiOi and CiCs, which electrically act as traps.
In order to investigate the effects produced by the irradiation, thermally stimulated currents without
external bias were measured [1], using a set-up with a Janis CCS-450 cryostat, a Keithley 6517A
electrometer and a Lakeshore 331 temperature controller, and a Newport VIS-NIR Cornerstone 260 1/4m
Monochromator System. Square samples of 1 cm length were cut from the irradiated wafers, and Al
electrodes were thermally evaporated on both sides, the top one being semitransparent.
The samples were cooled down at 70 K, and then they were illuminated through the top electrode
with monochromatic light (1000, 800 and 400 nm wavelength), for 20-30 min. in order to charge the traps
located in the depth where the light was absorbed. The trapped carriers produce a frozen-in electric field.
Subsequently, the sample was heated up at a constant rate of 6 K/min, up to 300 K, recording the
discharge current produced by the carriers released from traps and the equilibrium carriers as well. The
carriers move into the internal electric field produced by both the still trapped ones and the stopped iodine
ions (defined below).
When the surface was illuminated with light of 1000 nm wavelength, light is absorbed and traps are
filled in the whole region with irradiation defects. The temperature dependence of the discharge current is
plotted in Fig. 1, as dashed line. Two partially superposed maxima, located at 196 and 204 K, and one
shoulder, at 155 K, are clearly visible. Three much smaller maxima are also present, two of them at lower
temperature (see inset), and another one at higher temperature (~ 255 K).
111
Fig. 1. Discharge current in I irradiated Si after 1000 nm illumination: experimental (dashed) and
modeled (continuous) curves
For 800 nm wavelength illumination, when the region investigated below the surface is larger than 10
µm, the measured discharge current curve has the same structure as that recorded in Fig. 1 [1]. After the
illumination with 400 nm wavelength, which fills only the traps located close below the surface, it has a
main maximum at 196 K, a small shoulder at 205 K, and a prominent tail at the highest temperature [1].
The fractionary heating curves give the activation energies of 0.19, 0.28 and 0.41–0.46 eV range. For
800 nm illumination, the supplementary value of 0.51 eV was found.
The discharge currents were calculated by using the model developed in Ref. [2]. The experimental
curves were modeled with six traps. Consequently, a system of six coupled differential equations for the
concentrations of trapped carriers, electrons (nti(T)) and holes (ptj(T)), was numerically solved, taking as
start values for the activation energies (Eti) those experimentally determined from fractionary heating
measurements. By modeling, the range of 0.41 – 0.46 eV activation energies was resolved into three
trapping levels. Plausible values for the cross sections σi in agreement with the literature were used as
start values, too.
The point defects act as ‘normal traps’, i.e. are filled at the lowest temperature by illumination, and
release charge carriers du-ring heating, modifying the electric field. Iodine ions stopped in the sample,
being much bigger and heavier than Si ones, produce a local deformation in the crystal, which we
described by a local, permanent electric field, not depending on temperature, Eiodine. It is superposed to the
frozen-in electric field due to the trapped charge, and the total field becomes:
E
=
(T ) Eiodine + ed
∑ j ptj (T ) − ∑ i nti (T )
ε 0ε r
(1)
where e is the electron charge, d the depth with defects, ε0 the vacuum permittivity, εr the Si relative
permitivity, and the sums are made on all trapping levels.
112
The total current is calculated [1] as the algebraic sum of electron and hole contributions. Each of the
currents is due to both non-equilibrium detrapped electrons (Δn) and holes (Δp) and to equilibrium
carriers, all of them moving in the total electric field. The calculation of Δn(T) and Δp(T) takes into
account the capture coefficients of all defect levels, the lifetimes of electrons and holes. The electron
current is:
In(T)=-eA[Δn(T)+ni(T)]µnE(T)
(2)
with A the top electrode area and µn the electron mobility. The hole current has a similar expression.
The traps parameters, as well as EIodine are adjusted to fit the experimental curves. The parameters
calculated for 1000 nm illumination wavelength are presented in Table 1, and the calculated current is
drawn with continuous line (Fig.1).
Tab. I. Calculated trap parameters, 1000 nm wavelength illumination
Type
E
Cross
section
Assigned to
[cm2]
N
0.17
1x10–17
VO/CiCs
P
0.3
1x10–15
CiOi
N
0.41
3x10–16
V2
N
0.435
10–16
-
N
0.46
4.8x10–17
VP
N
0.53
5x10–18
-
The cross sections for the 6 traps were simultaneously adjusted by modeling for all three illumination
wavelengths to the values presented in Table I. A set of six activation energies was obtained for 1000 and
800 nm wavelength, and a set of only five for 400 nm. In the last case, the deepest trapping level is no
more charged, being spatially located deeper than 8 nm in the sample. For each trap, the activation
energies obtained for the three illumination wavelengths are in a range of 2% error. The traps are assigned
to defects in accordance to the results published in the literature, and also taking into account the
impurities present in the sample.
References
[1] S. Lazanu, A. Slav, A.-M. Lepadatu, I. Stavarache, C. Palade, G. Iordache and M.L. Ciurea, Appl.
Phys. Lett. 101, 242106 (2012).
[2] M.L. Ciurea, V. Iancu and M.R. Mitroi, Solid State Electron. 51, 1328 (2007).
113
Epitaxial ferromagnetic samarium grown on Si(001)
N.G. Apostol, R.M. Costescu, M.A. Husanu, G.A. Lungu, D.G. Popescu, D. Macovei,
I. Pintilie, C.M. Teodorescu
There is a great deal of interest in synthesizing magnetic structures on semiconductors for the
emerging field of spintronics. Quite often, magnetic metals deposited on semiconductors form
complicated interfaces, substrate disrup-tion, absence of long range order and sub-stantial reduction of
magnetic moments, as was recently shown for Fe/Si(001) [1].
Fig. 1. Si(001) ideal primitive cell, together with the atomic radii of Si, Fe and Sm [3].
114
Fig. 2. Low energy electron diffraction (LEED): (a), (b): clean Si(001) (2 x 1); (c): 3.25 nm Sm/Si(001)
deposited at 100 °C; (d): 3.25 nm Sm/Si(001) deposited at 300 °C; (e): Si(001) LEED spot profile
analysis (SPA) from (a);(f): Sm/Si(001) LEED-SPA from (d). [2]
Fig. 3. X-ray photoelectron spectroscopy for Si 2p (a) and Sm 3d (b) [2].
115
Fig. 4. Evolution of Sm 3d XPS spectra for a film synthesized at room temperature with the in situ
contamination in the analysis chamber.
This study presents for the first time a complete investigation of atomic structure, long range order,
electronic configuration and magnetic properties of Sm deposited on Si(001) [2,3]. Sm is a promising
magnetic candidate for low intermixing with Si, owing to its larger atomic radius (Fig. 1) [3]. It was
proven that Sm depo-sited on Si(001) exhibit long range order (Fig. 2) [2]. X-ray photoelectron spectroscopy (XPS) analysis (Fig. 3) have shown the simultaneous presence of Sm0, Sm2+ and Sm3+ [2]. This
study attributes for the first time correctly the Sm 3d XPS compo-nents, namely it was proven that the
component at ~ 1074 eV is due to Sm metal and not to Sm2+. This is visible also from Fig. 4, which
represents in situ oxidation of a Sm layer due to the residual gas (at a pressure of 5 x 10-10 mbar). Clear
evolution of Sm0 and Sm2+ intensities towards Sm3+ is observed, and this correlates also quite well with
the O 1s signal increase, yielding the final Sm2O3 compound [2]. X-ray absorption spectro-scopy (Fig. 5)
evidenced a decrease of the number of 5d holes with the deposition temperature (i.e. a reduction from
Sm3+ to Sm2+) [3]. The magnetic characterization (Fig. 6) confirmed that Sm0 and Sm3+ are ferromagnetic,
whereas Sm2+ in SmSi2 is not ferromagnetic [2,3], since the satura-tion magnetization decreases with the
same amount as the decrease of Sm0 and Sm3+.
116
Fig. 5. Sm LIII-edge X-ray absorption spectra for Sm/Si(001) synthesized at different temperatures [3].
Apart for the first correct attribution of the Sm 3d XPS components, this study evidenced also a
noticeable variation of the Sm 3d spin-orbit splitting with the Sm ionization state: the variation exceeds
1.2 eV from Sm0 to Sm3+ [2].
Fig. 6. Magneto-optical Kerr effect hysteresis loops for Sm/Si(001)synthesized at different temperatures
[2].
References:
[1] N.G. Gheorghe, M.A. Husanu, G.A. Lungu, R.M. Costescu, D. Macovei, C.M. Teodorescu, J. Mater.
Sci. 47, 1614 (2012).
[2] R.M. Costescu, N.G. Gheorghe, M.A. Husanu, G.A. Lungu, D. Macovei, I. Pintilie, D.G. Popescu,
C.M. Teodorescu, J. Mater. Sci. 47, 7225 (2012).
117
[3] N.G. Gheorghe, G.A. Lungu, M.A. Husanu, R.M. Costescu, D. Macovei, C.M. Teodorescu, Appl.
Surf. Sci. 267, 106 (2013).
Measuring the phase of the electron without interferometry, by using
isospectral shapes
M. Ţolea, B. Ostahie, M. Niţă, F. Ţolea and A. Aldea
National Institute of Materials Physics, POB MG-7, 77125 Bucharest-Magurele, Romania.
When one thinks about phase
measurements, interference is the first word
coming to mind - and it was actually the only
word for quite a long time. However, C.R.
Moon et.al [1] -in a remarkable recent
experiment- demonstrated that isospectrality
can also be used to extract phase distributions
(this is possible because the wave functions of
the isospectral shapes respect a particular
relation, called transplantation, which brings
the needed supplementary information). Their
approach enlarge the group of famous
mathematical problems that attracted a great
interest from physicists as well. The particular
famous problem we talk about is the
isospectrality debate launched by Kac in 1966
[2]when he asked: "Can one hear the shape of
a drum"? It was known that the spectrum
uniquely determined the area and the
perimeter of a "drum", but whether it also
contained the full shape information was yet
to be researched. It wasn't until 1992 that
Gordon et.al. [3] in a milestone paper,
answered negatively to the famous question by
finding different (noncongruent) shapes with
identical spectra. However, isospectrality
remains a high exception, only 17 such classes
of pairs being known [4] and it is believed that
no others exist.
The most simple pair of isospectral
shapes is the Bilby-Hawk pair, depicted in
Fig.1 (where the transplantation procedure is
also shown).
Recently - and this was the motivation
of our paper - isospectrality has found a direct
application
in
experimental
quantum
mechanics, by allowing the extraction of the
electron's phase, in a non-interferometric way.
We refer to the experiment of Moon [1], who
realized isospectral shapes by planting CO
molecules on copper surface with the use of an
STM tip.
118
The principle of the phase extraction is
very simple (once revealed): it can be shown
that, if one has two isospectral shapes, one can
build the eigenfunctions of one shape by using
combination of parts from the corresponding
eigenfunction of the other shape. The
procedure is called "transplantation" and this
brings supplementary information which are
used to find the phase distribution of the
eigenfunctions (if the amplitude distributions
are known). For instance, the wave function in
the triangle 1 of Hawk can is equal to the
linear combination of Bilby triangle functions
A-E+F. Directly measurable are of course the
Fig.1: The "Bilby" shape (left) and "Hawk"
shape (right) are isospectral. Their wave
functions can be built one from the other. A
schematic description of the the transplantation
procedure is shown. The Hawk eigenfunction in
triangle 1 - chosen as example in this plot- , can
be expressed as a combination of parts from the
corresponding eigenfunction of Bilby, by adding
the function in triangles A and F and
substracting the function in E.
amplitudes |1|, |2|,...|7|, |A|, |B|,...|G|. The
transplantation relations bring a new set of 7
equations allowing to extract also the phase
distributions- see [1,5] (the wave functions
can be chosen real, therefore the phase is
synonym to the sign).
In our recent paper [5], we focus on
the study of isospectral shapes (in particular
the Bilby-Hawk pair) under the influence of
disorder, with an emphasis on the phase
extraction procedure. A certain level of
disorder or roughness of edges can
compromise the isospectrality-based phase
extraction in the same way in which inelastic
scattering
or
environment-induced
decoherence
can
compromise
the
interferometry-based phase extraction. The
aspect may be of interest because the
experimental conditions, for instance, are
never quite perfect, and isospectrality can only
be closely approached. If, for instance, the
isospectral shapes are carefully prepared on a
flat surface, the disorder effects may come
from small defects, oscillations of the atoms
due to temperature, tiny movements of the
STM measurement tip, etc.
The are many ways in which disorder
or impurities can be introduced. In [5] we
present the result of averaging (the measurable
quantities, such as energy levels and wave
functions amplitudes) over large ensembles of
disorder configurations of variable amplitude
(diagonal Anderson disorder is considered).
With disorder, isospectrality, as well as the
transplantation procedure do not hold
rigourously. One can however still define a
119
"measurable" or "extracted" phase simulating
the experimental procedure: we will use the
(disordered
averaged)
wave
function
amplitudes and search numerically the phase
distribution that leads to the best fit after
transplantation.
We found that this extracted phase
coincides - up to negligible differences - with
the phase of the "clean" shapes, if the disorder
is below a given amplitude, corresponding to
5% misfit of the wave functions after
transplantation. Our main result is shown in
Fig.2, where we show the effect of increasing
disorder on the phase extraction for the first
mode of Bilby (similar conclusions can be
derived for the other modes as well).
[1] C.R. Moon, L.S. Mattos, B.K. Foster, G.
Zeltzer, W. Ko, H.C. Manoharan, Science
319, 782 (2008).
[2] M. Kac, Am. Math. Mon. 73, 1 (1966).
[3] C. Gordon, D. Webb, S. Wolpert,
Inventiones Math. bf 110, 1 (1992).
[4] O. Giraud, K. Thas, Rev.Mod.Phys. 82,
2213 (2010).
[5] M. Ţolea, B. Ostahie, M. Niţă, F. Ţolea, A.
Aldea, Phys.Rev.E 85, 036604 (2012).
Fig.2: Evolution with increasing disorder of the
averaged -over 1000 disorder configurationswave function amplitude (first row) and the
corresponding "extracted phase" (second row)
for the first mode of Bilby. The disorder
amplitude, from left to right, is 0, 0.2, 0.3, 0.4
and 0.7. A significant deviation of the phase
from the ideal (disorder-free) case can be
noticed for disorder higher than 0.3.
120
Glass-ceramic microrods prepared by sol-gel template method
M. Secu, C.E. Secu, Mariana Sima, M. Sima Raluca Negrea and L. Mihut
Sol-gel method has been proved very useful for obtaining glassy nano-composite materials, i.e.
the so called glass ceramics, in which rare-earth doped fluoride nanocrystals are embedded [1-4].
Through a controlled nucleation and crystallisation process the initial xerogel is thermally converted into
a glass ceramic composed by a low phonon energy nano-crystalline fluoride phase dispersed within the
glass matrix. As consequence it was observed an improvement of their performances over the fluoride
glasses that make them useful in a broad range of photonics applications.
The concepts of sol-gel chemistry and template preparation of nanomaterials have been proposed
to yield a new general route for preparing semiconductor nanowires of by conducting sol-gel synthesis
within the pores of various micro- and nanoporous template membranes [1]. These nanowires represent
the smallest dimension that can be used for the efficient transport of electrons and optical excitations and
sustain the next generation of optoelectronic nanodevices [2].
We used sol-gel chemistry within the pores of a polycarbonate template membrane for the
preparation of xerogel and glass-ceramic microrods in which luminescent Eu3+-doped BaF2 nanocrystals
are embedded. Silica xerogels have been prepared from liquid solution of organometallic tetraethylorthosilicate (TEOS) precursor in the presence of trifluoroacetic acid (TFA) as catalyst. The capillary
force drives the sol into the pores of the template membrane; then it is withdrawn, dried and dissolved in
dichloromethane and finally xerogel rods are obtained. Glass ceramization was achieved after annealing
at elevated temperatures.
In Figure 1 are depicted the SEM images of the glass-ceramic microrods of about 0.8µm
diameter and 10µm length. Inside these ones nanostructures of about 30-40nm size can be observed. Their
nature was revealed by the transmission electron microscopy (TEM) on bulk samples that have indicated
BaF2 nanocrystals [5].
121
Fig. 1: SEM images of glass-ceramic rods at two different magnifications; nanostructures of about 30-40
nm are observed inside.
As Eu3+-ion has been widely used as a structural probe of crystalline and glassy materials, the
features of its characteristic PL spectra have been used to extract information about the local environment
around the ion.
Photoluminescence spectra recorded on Eu3+-doped glass-ceramic microrods and bulk are
depicted in the Figure 2 where we can recognize typical Eu3+-ion transitions 5D0→7FJ (J=1-4). In the
xerogel rods or bulk the Eu3+ ions are embedded in the pores of a three-dimensional SiO2 macromolecule
with a D3h coordination symmetry around the ions [6]. During ceramization at 800 °C silica network is
formed and this process is accompanied by the precipitation of the BaF2 nanocrystals [5]. The Stark
122
splitting of the PL bands (Figure 2) is due to the degeneracy level removal by the crystal field indicating
that a number of Eu3+-ions are taken inside the BaF2 nanocrystals [5].
7
7
Luminescence (arb.units)
F1
glass-ceramic rods
glass-ceramic bulk
F2
7
F4
7
F0
7
F
3
580 600 620 640 660 680 700 720
Wavelength (nm)
Fig. 2: Normalised photoluminescence spectra recorded on Eu3+-doped glass ceramic rods and bulk
Glass-ceramic rods
Glass-ceramic bulk
D0→ 7F2
5
ν =180cm-1
ν =130cm-1
15600
15800
16000
16200
16400
-1
Energy (cm )
Fig. 3: Photoluminescence 618nm band showing the vibrational structures in glass-ceramic bulk and
rods.
In the glass ceramic rods the intensities of the 5D0→7F1 and 5D0→7F2 are comparable (Figure 2)
indicating that Eu3+-ions occupy low coordination symmetry sites within the BaF2 nanocrystals. On the
other hand in the glass ceramic bulk Eu3+-ions ocuppy higher symmetry coordination sites [5]. Moreover,
higher broadening of the 5D0→7F0 luminescence in the glass ceramic rods compared to the bulk shows
multiple Eu3+-ion sites in the first case. In the glass ceramic rods the 618 nm luminescence band shows a
vibronic structure (ν=130cm1-) different from the glass ceramic bulk where is better resolved (Figure 3).
123
All the experimental facts shows that in the glass-ceramic microrods and bulk Eu3+-ions occupy
different sites inside the BaF2 nanocrystals with distorted environment around the ion. This indicates an
influence of the dimensional constraints imposed by the membrane pores during xerogel formation and
subsequent glass crystallization [7].
Combination of the wide range of achievable materials and relatively easiness of the sol-gel
method with the template preparation method allow exploiting the advantages of the light-guiding
properties of the rods to produce guiding structures for applications in integrated optics.
References
[1] Fujihara S., Mochizuki C., Kimura T., J. Non-Crystalline Sol. 244, 267 (1999).
[2] Daqin Chen, Yuansheng Wang, Yunlong Yu, En Ma, Lihua Zhou J. Solid State Chem. 179, 532
(2006).
[3] C.E. Secu, M. Secu, C. Ghica, L. Mihut
Optical Materials 33, 1770 (2011).
[4] del-Castillo J., Yanes A.C., Mendez-Ramos J., Tichomirov V.K., Rodríguez V.D. Optical Materials
32, 104 (2009).
[5] Guozhong Cao, Dawei Liu, Advances in Colloid and Interface Science 136, 45 (2008)
[6] Barrelet, C., Greytak, A., Lieber, C. Nano. Lett. 4, 1981 (2004).
[7] M. Secu, C.E. Secu, M. Sima, Journal of Nanoparticles Research 14, 772 (2012).
124
Microstructure-related magnetic properties in Co-implanted ZnO layers
L. C. Nistor, C. Ghica, V. Kuncser
in cooperation with
D. Pantelica,
National Institute of Physics and Nuclear Engineering, Magurele, Romania
J.-J. Grob
Institut d’Electronique du Solide et des Systèmes, Strasbourg, France
G. Epurescu, M. Dinescu
National Institute of Lasers, Plasmas and Radiation Physics, Magurele, Romania
Beside the useful intrinsic (bulk) properties and large morphological variety of the ZnO
nanostructures, a new possible application of ZnO has been identified in spintronics after the theoretical
prediction showing that appropriately doped ZnO could act as dilute magnetic semiconductor (DMS) [1].
The debate on the ferromagnetic properties of transition metal (TM) doped ZnO should rely on the
correlation between the magnetic properties and structural information, which is not obvious due to the
difficulty in detecting very small precipitates, but also in specifying their nature [2].
Our work concerns the careful correlation of microstructural and magnetic properties of Coimplanted ZnO/MgO thin films by a comprehensive analytical TEM investigation corroborated with
magnetic characterization [3].
The ZnO thin films (∼200 nm thickness) were grown in a conventional PLD system used in
conjunction with an RF discharge plasma beam [4]. The Co implantation was carried out at the InESS
facility. The implantation was performed at room temperature, fluences of 1 × 1016 cm−2 (low fluence LF) and 1 × 1017 cm−2 (high fluence - HF) and energy of 200 keV. The microstructure characterization
was carried out on cross-section specimens by HRTEM / HRSTEM using the Cs probe corrected JEMARM/200F analytical electron microscope operated at 200 kV. EDX and EEL spectroscopy as well as
EELS spectrum imaging in STEM mode (EELS-SI) were performed with the GIF Quantum SETM
Imaging Filter. Thermo-magnetic curves and magnetic hysteresis loops at temperatures between 5 and
300 K were measured with a SQUID magnetometer (Quantum Design).
At the lower irradiation fluence, the LF thin film morphology is not altered substantially, as
compared with the non-irradiated film, conserving its columnar growth along the c-axis of ZnO. At the
higher fluence, the morphology of the film is heavily disordered. The top half of the ZnO film is
completely amorphized by the ion bombardment. The bottom half consists of a mixture of defected
crystalline and amorphous regions. Precipitation of a second
125
phase was observed in both HRTEM and electron diffraction, as well dispersed, crystalline Co nanoparticles (2-5 nm).
Figure 1. HRSTEM images of Co nano-precipitates embedded in the HF ZnO film: (a) bright field and (b)
dark field (HAADF) images of a hexagonal Co nano-particle in [0002] orientation; (c) HAADF image of
a cubic Co nano-particle in [002] orientation.
The Co nano-particle in the BF-STEM and HAADF-STEM images in Figure 1 a and b shows a highly
disordered atomic structure consisting in a mixture of hexagonal and cubic close-packed phases (hcp and
ccp) and a high density of planar defects. STEM-EDX line scan has been acquired across the interface
(arrow in Figure 2) to check the chemical composition of the observed nanoprecipitates.
Figure 2. Cross-section HAADF STEM image and EDX line profile of the chemical elements in the HF
sample.
The variation of the atomic concentrations for the detected elements is given at the bottom part of Figure
2. From the correlation between the O, Zn and Co EDX signals (Co maxima corresponding to O and Zn
126
minima) we conclude that the nanoprecipitates are of metallic Co. Also, ∼2 at% Co is noticed in the
whole layer as small atomic clusters or Co atoms dissolved in the ZnO lattice.
Figure 3. Cross-section HAADF STEM image of Co precipitates embedded in the ZnO matrix (HF
sample). EELS-SI images for Co-L, O-K, and Zn-L edges.
EELS-SI experiments further confirmed the nature of the observed nanoprecipitates (Figure 3). The
extracted elemental maps show the relative elemental composition. The complementary Co and O signals
confirm the formation of metallic Co nanoprecipitates.
The presence of metallic Co precipitates in the HF sample revealed by AHRTEM investigations,
provides the starting point for the interpretation of the magnetic data.
Figure 4. Magnetization data on the HF sample: hysteresis loops with subtracted diamagnetic and
paramagnetic signal.
The magnetization curves indicate the presence of a ferromagnetic ordered state in all samples,
including the non-implanted one The temperature evolution of the magnetic susceptibility has to be
related to the superposition of two supplementary magnetic signals with a linear dependence on the
magnetic field: a paramagnetic contribution dominant at low temperatures and a diamagnetic contribution
dominant at high temperatures. The hysteresis loop of finite coercivity at room temperature for the HF
sample (Figure 4) cannot be related to the Co clusters. These precipitates with a wide size distribution,
127
going down to the atomic level of either substitutional or interstitials Co centres contribute essentially to
the paramagnetic / superparamagnetic magnetization at low temperatures.
We consider that these findings should be taken into consideration when preparing and
characterizing ferromagnetic DMS thin films for future applications in spintronics.
References
[1] Dietl H, Ohno F, Matsukura F, Cibert J and Ferrand D, Science 287, 1019 (2000)
[2] Kaspar T C, Droubay T, Heald S M, Egelhard M H, Nichimuthu P and Chambers SA, Phys. Rev. B
77, 201303(R) (2008)
[3] Nistor LC, Ghica C, Kuncser V, Pantelica D, Grob JJ, Epurescu G and Dinescu M, J. Phys. D: Appl.
Phys. 46, 065003 (2013)
[4] Nistor LC, Ghica C, Matei D, Dinescu G, Dinescu M and Van Tendeloo G, J. Cryst. Growth 277, 26
(2005)
Magnetic defects in crystalline Zn(OH)2 and nanocrystalline ZnO resulting
from its thermal decomposition
S. V. Nistor, D. Ghica, M. Stefan, I. Vlaicu, J. N. Barascu, C. Bartha
Zinc hydroxide, Zn(OH)2, has attracted a lot of interest as a precursor in the synthesis of nano-ZnO.
Zn(OH)2 can be also formed on the surface of ZnS/ZnSe/ZnO nanocrystals (NCs), either during their
preparation, resulting in a core–shell structure, or in a later stage by atmospheric corrosion. The changes
observed in the optical properties of the ZnS/ZnO NCs, attributed to the presence of a Zn(OH)2 surface
layer [1,2], suggested that this layer could enhance the NCs optical properties. Monitoring the formation
and structure of the Zn(OH)2 surface layers by the usual X-ray diffraction (XRD) and transmission
electron microscopy (TEM) techniques is a difficult task, as one needs to distinguish the Zn(OH)2 present
in the atomic surface layers from other possible compounds such as ZnO, ZnCO3 or Zn5(CO3)2(OH)6, the
last two produced by atmospheric corrosion as well. Electron paramagnetic resonance (EPR) can detect
with high sensitivity the presence of these compounds by using low concentrations of Mn2+ impurity ions
as local atomic probes. The accurate determination of the spin Hamiltonian (SH) parameters is essential
for establishing the nature of the surrounding crystal lattice [3,4]. The success of this approach is
conditioned by the existence of accurate reference SH parameter values for the Mn2+ ions in the
corresponding bulk crystals. Up to now, there were no reliable reference values of the SH parameters of
the Mn2+ ions in Zn(OH)2.
128
We report here the results of an EPR investigation of crystalline Zn(OH)2 contain-ing trace amounts of
substitutional Mn2+ ions (<0.1ppm), before and during its thermal induced decomposition into nano-ZnO
[5]. Crystalline Zn(OH)2 was prepared by precipitation of a Zn-nitrate solution with NaOH. The EPR
measurements were carried out with the spectrometers from CetRESav (Centre for advanced ESR
techniques - http://cetresav.infim.ro). XRD and TG measurements were also performed.
ZnO
o
10
20
30
40
(103)
(102)
ε-Zn(OH)2
(021)
(311)
(112)
(211)
(111)
(201)
(110)
(101)
140 oC / air
AP
(110)
(101)
(100)
(002)
240 C / air
50
60
2 θ (degrees)
Figure 1. The XRD patterns of Zn(OH)2 before (AP) and after annealing, showing the complete
transformation into nano-ZnO at 140oC [5].
The EPR spectra of the samples pulse annealed in air at increasing temperatures display strong changes in
the 110–140oC temperature range, where, according to the TG and XRD measurements (Fig. 1), the
decomposition of the crystalline Zn(OH)2 into nano-ZnO takes place. The changes in the EPR spectrum
of the Mn2+ ions (Fig. 2) reflect local structural modification of the surrounding lattice. The SH
parameters of the Mn2+ ions, determined by simulation and lineshape fitting of the Q-band spectra of both
as-prepared and annealed at 240oC samples, are given in Table I. One notices that in the latter case the SH
parameters of the Mn2+ ions are practically identical with those reported for substitutional Mn2+ ions in
nano-ZnO produced by thermal decompo-sition of hydrozincite (called Mn2+-c centers) [6]. This result
demonstrates that the Mn2+ ions responsible for the EPR spectra observed in the samples annealed above
140oC are substitutionally localized at Zn2+ sites in the resulting nano-ZnO. The relative concentration of
the Mn2+ ions in the investigated samples remains practically constant with the annealing temperature.
Therefore the Mn2+ ions responsible for the EPR spectrum observed in the as-prepared sample, which are
completely transformed by annealing above 140oC into Mn2+ ions localized at substitutional Zn2+ sites in
the ZnO lattice, are also localized at similar cationic sites in the as-prepared Zn(OH)2.
Table I. SH parameters of the paramagnetic centers in Zn(OH)2 and resulting ZnO. The A, D and (D)
parameters are given in 10-4 cm-1.
129
SH
Mn2+
parm.
in
Mn2+-c
in
Mn2+ -d
in
ZnO
ZnO
NCs
disord.
SD
in
Zn(OH)2
ZnO
NCs
g‖
2.0010
2.0012
2.0012
1.9581
g﬩
1.9567
A
-87
-74
-73.5
-
|D|
70-600
242
242
-
(D)
85
17
102
-
Zn(OH)2
Q-band; RT
X
SD
exp.
2+
Mn
(a)
1200
1220
1240
Magnetic field (mT)
Zn(OH)2 ann. 240 oC/air
(b)
Ix40
X
exp.
Mn2+- c
Mn2+- d
1200
1210
1220
1230
1240
SD
1245
1250
Magnetic field (mT)
Figure 2. Experimental and simulated Q-band EPR spectra of crystalline Zn(OH)2: (a) as-prepared, (b)
pulse annealed in air at 240oC [5].
130
A low intensity EPR line (SD in Fig. 2), observed at g ~ 1.958 on the higher magnetic field side of the
Mn2+ spectrum, strongly increased during the thermal decomposition of the Zn(OH)2. The resulting
intense line (Fig. 2b) allowed us to perform a full line-shape analysis. The g-values (Table I) are
practically identical with those of the so-called shallow effective mass (EM) donor center, or briefly the
shallow donor (SD) center in ZnO. Its minute presence in the as-prepared Zn(OH)2 (Fig. 2a), indicates
that minute amounts of ZnO, beyond the detection limit of the XRD technique, were already present.
Another thermally stable, unknown paramagnetic center (called X) has been also observed (Fig. 2) in
Zn(OH)2.
In conclusion, by monitoring the EPR spectra in the as-prepared samples as well as during pulse
annealing experiments one could investigate the thermal decomposition of the crystalline Zn(OH)2 into
nano-ZnO, as well as the presence of minority phases, beyond the sensitivity limit of the XRD technique.
The accurate SH parameter values (Table I) of the substitutional Mn2+ ions in the crystalline Zn(OH)2
determined in this work are now available for further EPR investigations of the presence and stability of
the Zn(OH)2 phase in various II-VI semiconductor NCs, in particular in the core-shell nanostructures.
Nano-ZnO with a rather large concentration of shallow donor centers can be obtained by the thermal
decomposition of crystalline Zn(OH)2.
References
[1] A. A. Bol, A. Meijerink, J. Phys. Chem. Sol. B 105, 10203 (2001)
[2] M. Stefan, S. V. Nistor, D. Ghica, C. D. Mateescu, M. Nikl, R. Kucherkova, Phys. Rev. B83, 045301
(2011) and references cited therein.
[3] R. Beaulac, S.T. Ochsenbein, D. R. Gamelin, in V.I. Klimov (Ed.), Nanocrystal Quantum Dots, 2nd
edition, CRC Press (2010)
[4] M. Stefan, S. V. Nistor, N. J. Barascu, J. Magn. Res. 210, 200 (2011)
[5] S. V. Nistor, D. Ghica, M. Stefan, I. Vlaicu, J. N. Barascu, C. Bartha, J. Alloys Compd. 548, 222
(2013) – online Sept. 2012.
[6] S. V. Nistor, L. C. Nistor, M. Stefan, D. Ghica, Gh. Aldica, N. J. Barascu, Cryst. Growth Des. 11,
5030 (2011)
131
Nanoscale Physics
132
Tailoring ZnO properties by electrodeposition conditions
Elena Matei , Monica Enculescu, Nicoleta Preda, Ionut Enculescu
Electrochemical deposition represents an interesting approach for preparation of ZnO films with
taylored properties. These can be finely tuned for a wide range of applications from optoelectronic
devices such as LEDs and laser diodes to gas senors or catalysts. One characteristic of ZnO is its
nanostructures polymorphism. A wide range of nanoparticles or nanostructured thin films were prepared
by a variety of methods, such as tetrapods, prisms, columns, brushes and so on. By varying
electrodeposition parameters one can influence the morphology, the structure and the optical and
electrical properties of nanostructured ZnO films.
For potentiostatic conditions we used different experimental parameters in terms of bath
composition and overpotential for depositing ZnO films with high UV emission properties and with
morphologies of either platelets or prisms [1]. By ramp-like varying potentials with different sweep rates
we managed to fabricate films of hollow hexagonal prisms with a high structural orientation [2].
The electrochemical baths employed were Zn(NO3)2 aqueous solution with concentration ranging
from 0.05 to 0.2M and PVP (polyvynilpirrolidone) used in some cases as an aditive. We used a typical
three electrode set-up with a saturated calomel (SCE) reference electrode and a 2 cm2 platinum plate
counter electrode. The reference electrode was connected to the electrochemical cell by a 20 cm long salt
bridge filled with KCl, in order to avoid its contamination and to maintain its temperature close to room.
The cathode reactions taking place during the ZnO electrodeposition processes are the following:
2e- +NO3- + H2O→NO2- + 2OH-
(1)
Zn2+ + 2OH-→Zn(OH)2→ZnO↓ + H2O (2)
or the global reaction:
Zn(NO3)2 +2e-→ZnO↓ +NO3- + NO2-
(3)
The two step process represents a combination of electrochemical reduction of nitrate ions and a chemical
precipitation of zinc oxide. Practically, the first process is controlled through the deposition potential and
the bath concentration, while the second strongly depends on temperature.
Usually, in a potentiostatic mode the deposition of ZnO is performed at overvoltages higher than 900 mV.
133
Figure 1. Morphology of ZnO layers deposited from zinc nitrate baths: (top) low deposition potential;
(bottom) high deposition potential.
The SEM images of two typical layers of ZnO deposited in such a potentiostatic mode at two
different overpotentials are presented in figure 1. The size of the hexagonal columns depends on process
parameters i.e. concentration of zinc nitrate in the deposition bath, presence of additives and deposition
potential. A higher deposition potential leads to higher deposition rates and to hexagonal platelets
morphology.
The photoluminescence properties of electrodeposited ZnO layers are also strongly influenced by the
deposition conditions. The light emission is either due to near band to band recombination (excitonic peak
centered at approximately 375 nm) or related to point defects such as zinc or oxygen vacancies or
interstitials. This is the reason for which a strong UV emission becomes the synonym to a high quality
material. In figure 2 a set of emission plots are presented.
134
Figure 2. Luminescence emission measured for excitation at 365 nm: continuous curve deposited at -800
mV, dashed -900 mV, dotted at -1000 mV from a sollution containing 0.2M Zn(NO3)2, 0.1M KCl, 0.1%
PVP.
One can notice how for the sample grown at lower deposition potential and thus low deposition
rate we deal with a predominant excitonic emission while at high deposition rates the deffect related peak
at 570 nm becomes the most important.
Cathodoluminescence measurements performed on hybrid samples containing both prisms and
platelets proved that the platelets posses a much stronger defect related luminescence than the prisms.
We also tested the deposition for the potential varying linearly with time in the range -400 mV ÷ 1100 mV vs. SCE, sweep rates being: 0.1, 0.5, 1 and 20 mV/second. Also a sweep rate of -0.1 mV/second
was employed in the range -1100 mV ÷ -400 mV vs. SCE. [2]. We found that when using a direct
polarization sweep one will deal with hexagonal prisms with scattered dimensions. When reverse
polarization sweep was employed as in the case of the films prepared by direct polarization, the
deposition leads to layers of hexagonal structures uniform over large areas. However in this case the
prisms are hollow, their center being completely removed (figure 3).
Figure 3. ZnO layers deposited using 4 reversed potential sweep of -0.1 mV/second.
135
It is most probable that the process steps are better defined: a nucleation process takes place at
electronegative potential followed by the growth process and by a selective dissolution.
[1] Matei, E,; Enculescu, M ; Preda, N; Enculescu, I. MATERIALS CHEMISTRY AND PHYSICS, 134,
988-993, 2012
[2] Matei, E Enculescu, I., MATERIALS RESEARCH BULLETIN, 46, 2147-2154, 2011
Vortex depinning temperature in YBa2Cu3O7 films with BaZrO3 nanorods
L. Miu and I. Ivan
in cooperation with
D. Miu (INFLPR, Romania)
A. Crisan (University of Birmingham, England)
P. Mele (Hiroshima University, Japan)
Columnar defects are expected to be efficient vortex pinning centres, since vortices can be
confined over a large portion of their length if the external magnetic field H is oriented parallel to
the columnar pins. When the magnetic induction B inside the sample is below the matching field
BΦ (the field at which the vortex density and that of the columnar pins are equal) all vortices will
be localized on the columnar defects, at least in the low temperature T domain. According to the
Bose glass theory [1], for B(T) ≤ BΦ this state is limited up to the vortex depinning temperature
Tdp, above which vortices begin to wander away from their columnar pins, due to the
renormalization of the pinning energy barriers by thermal fluctuations. Since the correlated
disorder accommodates vortices below Tdp(B), the latter can be regarded as the vortex
accommodation temperature in static conditions (no current in the specimen). For YBa2Cu3O7
(YBCO) containing columnar defects along the c axis with the radius of a few nanometres
theoretical estimates [1] supply a Tdp value very close to the critical temperature Tc ~ 90 K (Tdp ~
0.95Tc).
In the last two decades the vortex dynamics in the presence of columnar defects was repeatedly
investigated using standard, zero-field cooling (zfc) DC magnetization relaxation measurements,
by determining the T variation of the normalized magnetization relaxation rate S =
−dln(m)/dln(t), where m is the irreversible magnetic moment (m ∝ J, the induced current
density in the sample) and t is the relaxation time. Detailed studies of the S(T) dependence at μ0H
< BΦ for YBCO single crystals and films with columnar tracks induced by irradiation or with
nonsuperconducting nanorods along the c axis revealed the occurrence of a maximum in S(T)
136
located around T = 30 K (see, for example, [2, 3]). This low-T S(T) maximum (Fig. 1) was
associated with a disappointing Tdp (~0.5Tc), attributed to a nonideal efficiency of the columnar
pins or to the easy expansion of double vortex kinks (DK).
YBZ0.3
YBZ1
YBZND1
0.4
105
104
m (emu)
Jcm (A/cm2)
106
0.2
0
30m
10
20
30
40
T = 70 K
50
H (kOe)
10
30
20
H (kOe)
40
50
Fig. 1. The S(T) variation at H = 2 kOe (perpendicular to the film) for YBCO films obtained by
PLD on (100) oriented SrTiO3 substrates from a YBCO target with 4 wt% BZO: YBZ0.3 - a 317
nm thick film with BZO nanorods preferentially oriented along the c axis (BΦ ~ 2 T), YBZ1 - a
1100 nm thick film with often interrupted, splayed BZO nanorods, and YBZND1 - a 1100 nm
thick film with the highest BZO nanorod splay, due to the use of an Ag-nanodot decorated
substrate. The low-T maximum is caused by the occurrence of thermo-magnetic instabilities
(TMI), whereas the maximum at TM appearing for a small nanorod splay transforms into a wide
S(T) minimum when the nanorod splay and the pinning energy dispersion is considerable. Ta is
the vortex accommodation temperature for finite J, and Tdp < Ta(J).
As known, for identical parallel columnar defects once a DK is created there is no energy
barrier preventing the entire vortex from moving to the next column, and S could take large
values. However, the pinning energy dispersion is expected to block the DK expansion, and
considerable efforts have been made to avoid the detrimental double vortex-kink formation, by
introducing splayed columnar defects.
The discrepancy between the theoretical Tdp and the interpretation of the results of DC
magnetization relaxation measurements was recently addressed in Ref. [4], where it was shown
that in the case of thin YBCO films with BaZrO3 (BZO) nanorods along the c axis the
temperature interval for the DK excitation and the variable range vortex hopping regime (VRH),
involving double vortex super-kink formation, is located at T values much higher than previously
believed [2, 3].
137
S = –∆ln(m)/∆ln(t)
0.08
YBZ0.3
YBZ1
YBZND1
0.06
TM
↓
Ta
↓
0.04
0.02
H = 2 kOe
TMI
0
0
30
60
90
T (K)
Fig. 2. U* vs 1/J (with J - the T dependent current density induced in the specimen) in a log-log plot,
where the slope is the creep exponent p, for YBZ0.3 and YBZND1 in H = 2 kOe. TM and Ta from Fig. 1
are indicated by arrows. The appearing vortex excitations are identified through the creep exponent p
(half vortex loops HL with p = 1, DK, with negative p) and creep processes (VRH, p = 1/3, single vortex
creep SVC, p = −1, and collective creep CC, p = 1.5). At low T, the presence of thermo-magnetic
instabilities (TMI) leads to an unphysical U*(1/J) upturn. The continuous lines represent a linear fit.
The identification of various vortex creep regimes and vortex excitations through the creep
exponent p in U*(J) ∝ (Jc/J)p (Fig. 2), where Jc is the critical current density, led to a good
agreement with the prediction of the Bose glass theory for Tdp [1]. Our study allows the
following conclusions:
1. The low-T S(T) maximum at around 30 K (Fig. 1) is generated by the presence of thermomagnetic instabilities (TMI);
2. The influence of DK and VRH manifests itself in the case of small nanorod splay through the
occurrence of another S(T) maximum, located at a higher temperature (TM in Fig. 1);
3. The vortex accommodation temperature Ta(J), located at the S(T) deep observed in the case of
YBZ0.3 (Fig. 1), is in agreement with the prediction of the Bose glass theory for Tdp, since Tdp <
Ta(J);
4. By increasing the nanorod splay and the pinning energy dispersion (in thick films, or using
nanorod decorated substrates, as well as in the case of a complex pinning landscape) the relevant
changes in the S(T) variation for H < BΦ (see Fig. 1) appear at high T [5], supporting our
identification of DK, the VRH regime and the location of Tdp [4]. The detrimental effect of
vortex excitations involving double vortex kink and superkink formation is diminished in thick
YBCO films with BZO nanorods, and almost vanishes when a nanodot decorated substrate is
used. The S(T) maximum at TM is substituted by a wide minimum (Fig. 1). This naturally appears
due to the increase of the nanorod splay and pinning energy dispersion.
.
References
[1]
[2]
[3]
Nelson D R and Vinokur V M 1993 Phys. Rev. B 48 13060
Maiorov B et al. 2009 Nature Mat. 8 398
Haberkorn N et al. 2012 Phys. Rev. B 85 174504
138
[4]
[5]
Miu L 2012 Phys. Rev. B 85 104519
Miu D, Ivan I, Crisan A, Mele P, Jakob G and Miu L 2013 Supercond. Sci. Technol. (in
press)
Nanoscale magnetic effects probed at the interfaces of magnetic
nanostructures
O Crisan and V Kuncser
in cooperation with
V. Uzdin (Saint-Petersburg State University, Saint-Petersburg, Russia)
W. Keune (University Duisburg-Essen, Duisburg, Germany)
V.R. Reddy (UGC-DAE Consortium for Scientific Research, Indore, India)
M. Angelakeris (Aristotel University, Thessaloniki, Greece)
One of the most widely researched topics over the last decades has been magnetic nanoscale systems. It is
unambiguous that the interest for tailor-made and properly functionalized magnetic nanostructures is very
wide and expected results will be of enormous benefit for the global economy. Still, researchers should
improve the manufacture of nanomaterials on a larger scale at a lower cost. Although computer modelling
may provide a hint in finding a structure that minimizes the internal energy, control of nanoscale
magnetic effects at the interfaces in magnetic nanostructures [1] in real time is still challenging in most
cases. In this regard, even if certain prerequisites should be fulfilled for specific applications, magnetic
nanoscale systems exploitation lays in the control of their interface properties. Such interface properties
are studied in two sets of different systems, the (Sm,Co)/Fe [2] and FePt/(Fe,Co) [3] exchange spring
bilayers and multilayers.
In the first system, conversion electron Mossbauer spectroscopy (CEMS) measurements in external
magnetic fields were performed on (Sm-Co)/Fe bilayer samples having a thin 57Fe probe layer placed at
different distances from the (Sm-Co)/Fe interface to obtain site-selective (isotope selective) data during
the magnetization reversal process. A generalized theoretical model was then applied to describe, via
electronic-structure calculations, the experimental data at the quantum-mechanical level. An atomistic
description of the noncollinear Fe spin structure in the magnetically soft Fe layer is thus obtained [2]. The
RT magnetic hysteresis loops along the easy-axis direction of five Sm-Co(20 nm)/Fe(20 nm) are typical
for layered exchange-spring magnetic systems. Upon decreasing the field from positive saturation, a sharp
drop of the magnetization occurs at the so-called nucleation field μ0Hn, followed by a signature of
saturation around μ0H = 350 mT. Separate switching transitions are observed for the Fe and Sm-Co
layers. The nucleation field Hn in the low-field range reflects the reversible magnetization reversal of the
soft Fe layer, whereas the switching field Hirr in the high-field region is indicative for the irreversible
switching of the hard Sm-Co layer. The CEMS spectra of the (Sm,Co)Fe bilayers gave valuable
information on the Fe spin configuration at different depths in the soft-magnetic layer, providing support
139
for specific material related parameters, required by the theoretical model proposed for explaining the
exchange spring behavior.
In the second system, the ion beam sputtered FePt/Fe bilayers presenting in-plane exchange spring
behavior, the challenge was to observe the changes in the interfacial exchange coupling by substitution of
Fe with Co. Two samples, FePt/Fe and FePt/Co/Fe were synthesized by ion beam sputtering and
analyzed. Fig. 1 shows the in plane M–H curves of both samples measured at 300 K using VSM. The
observed M–H data are characteristic of a two-phase system as one can see just two switching fields. The
magnetization decrease at higher negative fields is attributed to the hard magnetic layer which presents
consequently only one magnetic component of intermediate hardness. One would expect a single loop if
both (soft top and hard bottom layers) would be rigidly coupled, which is not our case, proving thus
moderate in plane anisotropy of the hard layer and moderate soft-hard magnetic (SM/HM) interfacial
coupling.
Fig.1: In-plane M–H loops of FePt/Fe (up) and FePt/Co/Fe (down) samples measured by VSM with the field applied along the
sample plane
CEMS gives strong support for the in plane spin reorientation in the soft layer, but also shows that
microscopic mechanisms and interfacial magnetic defects at the Fe/Co interface might play also a role
with respect to the unexpected value of the overall effective stiffness coefficient, AFeCo. As compared to
other layered systems manifesting in plane exchange spring effects, the present systems are characterized
140
by a very sharp decrease of the magnetization at a quite low switching field of the soft magnetic layer.
This behavior suggests either a relatively low exchange coupling at the HM/SM interface, or a low
exchange coupling inside the SM layer. It raises the question concerning the magnitude of the negative
field which still allows the complete regain of the initial magnetization in the SM layer when it is
released. The procedure we propose is basically a recoil curve procedure, in low fields regime. The
sample was magnetized to the saturation by the application of a 2 T positive field. The field was
subsequently decreased to zero i.e., inducing the remanence of the sample. Increasing negative magnetic
fields were then applied to the sample and then released, with the measurement of corresponding
magnetization values. In Fig. 2 one can see that in FePt/Co/Fe sample, the magnetization of the soft layer
returns to the initial remanent state for fields up to −0.6 T, whereas for FePt/Fe sample, this value is −0.2
T, which is close to the switching fields
of the hard layers in the respective samples.
Fig. 2: M-H data showing the spring effect in FePt/Co/Fe
The peculiarities of the interfacial exchange coupling allowed us to tune unexpectedly in this system, the
exchange spring performances only by substituting partially the Fe soft layer by a Co soft layer.
References
[1] M. Angelakeris, O. Crisan, C. Martinez-Boubeta, „Magnetic Interfaces at the Nanoscale: From Fundamentals to
Technological Applications”, book, Hindawi Publishing Corporation (2012)
141
[2] V. Uzdin, V. A. Vega, A. Khrenov, W. Keune, V. E. Kuncser, J. S. Jiang, and S. D. Bader, Phys. Rev. B 85 (2012)
024409
[3] V.R. Reddy, O. Crisan, A.Gupta, A.Banerjee, V. Kuncser, Thin Solid Films 520 (2012) 2184
Angular magnetoresistance of stretched carbon nanotube sheets
V. Sandu
in cooperation with
E. Cimpoiasu, (United States Naval Academy, Annapolis, USA)
G. A. Levin (Air Force Research Laboratory, Wright-Patterson AFB, USA)
A. Simpson and D. Lashmore (Nanocomp Technologies, USA)
Carbon nanotubes have unique properties, such as anomalously large electrical and thermal
conductivities [1]. There is considerable interest to take advantage of these properties in bulk,
macroscopic materials such as fabrics or yarns. These materials are essentially 3D, hence, isotropic,
despite the one-dimensional character of the nanotube. One way to exploit the potential of CNs and to
enhance the anisotropy of the bulk materials is to partially-align the nanotubes. Several papers have
reported improvements of the electrical transport along the direction of the alignment, but the anisotropic
properties of these materials are not fully understood [2].
In order to shed light on the anisotropy of mechanically-stretched bulk sheets of carbon nanotubes
(Fig. 1), we used measurements of magnetoresistance as a function of the magnetic field B and the angle
between the magnetic field and the stretching direction [3].
Fig. 1 SEM images of the doped longitudinally-stretched sample.
Specifically, we measured the B-dependence of the resistance of bulk CN networks in field applied along
the stretching direction and along other two directions perpendicular to it, one in-the-plane and the other
one out-of-the-plane of the fabric for both as produced samples, which are undoped, (UD) and the
samples chemically treated with nitric acid which are doped (D).
The T-dependence of the conductance data normalized to the 40 K value, G/G40K, are shown in the
Fig. 2.
142
Fig. 2 The normalized conductance G/G(40 K) vs. the temperature T for all four samples. The cartoon is a
drawing of the measurement configuration. Red arrows indicate the stretching direction for the
longitudinally-stretched samples (left) and laterally-stretched samples (right). Inset: The T-dependence of
G2(T).
The UD samples exhibit non-metallic behavior for all the measured temperatures, while the D samples
were metallic at high temperatures down to 250 K and weakly nonmetallic below 250 K. G ~ T1/2 in the
case of the UD samples, down to 26 K, and like ln(T) in the case of the D samples, at all temperatures
below 60 K. Below 26 K, the UD samples transition towards a stronger localized regime.
The MR is composed of two contributions: i) ΔR/Rneg < 0 which saturates at high fields and is
consistent with field-induced reduction of the phase coherence length due to quantum interference effects
in self-intersecting trajectories; ii) ΔR/Rpos > 0 which is dominant below 20 K and consistent with the
VRH mechanism. In the D samples, the latter is visible only at 2 K.
The angular dependence of the magnetoresistence (AMR) appears to be a superposition of two
terms (Fig. 3 for laterally streched UD sample):
AMR = α sin 2 (θ ) + β sin 2 (2θ )
(1)
143
Fig. 3 The AMR (filled circles) decomposition in a twofold symmetric (empty squares) and a fourfold
symmetric (empty circles) contribution for the UD-lat sample. (a) B is rotated in the (zy)-plane (b) B is
rotated in the (yx)-plane.
We propose that the observed anisotropic effects are mainly a result of the coupling between the
magnetic field, the ferromagnetic catalyst nanoparticles, and the network of CNs. The process of partial
alignment results in certain alignment of the nanoparticles, which produces an overall easy axis of
magnetization along the stretching direction. When B is rotated away from this axis, magnetic torques are
produced, which change the local strain configuration and modify the band structure, thus changing the
overall resistance. The ensemble of chains of nanoparticles interacts with the magnetic field in that their
magnetic moments are subject to magnetic torques. These are likely to change (a) the resistance of the
joints between the nanotubes and (b) the internal stress. The resulting changes in the axial strains, the
bending and the shearing of the nanotubes alter the band structure and modify the resistance. We can
speculate that if the strain is lower when B|| (stretching direction) compared to B┴ (stretching direction),
then the resistance of the metallic network is smaller when B|| (stretching direction). That means ΔR/Rneg
is largest when B|| (stretching direction), which is the case for the undoped samples. For localized
transport, if the strain is reduced when B|| (stretching direction), then the energy gap increases and the
resistance increases as well. The result is a positive magnetoresistance that is largest when B|| (stretching
direction). The nitric acid treatment affects the transport by improving the intertube junctions and the
charge carrier density [4].
144
The observed angular dependence is mirrors the fact that although the fibers are in average
aligned along the longitudinal x-axis, there are fibers which are oriented away or perpendicular to this
direction. The transport along these misaligned fibers will contribute to the angular dependence.
References
[1]
M. Meyyappan, “Carbon Nanotubes: Science and Applications”, CRC Press LLC: Boca Raton,
FL, 2005.
[2]
J.E. Fisher et al., J. Appl. Phys. 93, 2157 (2003).
[3]
E. Cimpoiasu, V. Sandu, G. A. Levin, A. Simpson, D. Lashmore, Angular Magnetoresistance of
Stretched Carbon Nanotube Sheets, J. Appl. Phys. 111, 123721 (2012)
[4]
P.N. Nilmalraj et al., Nanoletters 9, 3890-3895 (2009).
Electronic effects at self-assembled 4,4_-thio-bis-benzenethiolate protected Au
nanoparticles on p-GaAs (1 0 0) electrodes
C.C. Negrila, M.F. Lazarescu, I.Mercioniu
National Institute of Material Physics, Bucharest, Romania
in cooperation with
M.Enache, L.Preda, M. Anastasescu, G.Dobrescu, V.Lazarescu
Romanian Academy-Institute of Physical Chemistry ‘‘Ilie Murgulescu’’ Bucharest, Romania
E.Santos
Institute of Theoretical Chemistry, Ulm University, Germany
The XPS, SHG, AFM and EIS investigations were used in order to examine the effects of the
self-assembled 4,4_-thio-bis-benzenethiolate protected gold nanoclusters onto a p- GaAs (1 0 0)
electrode. Self-assembling techniques are of particular interest for electronic device and
materials applications since they provide means to control the semiconductor electronic
properties, and/or to build novel structures. Due to their relative stability and ease of forming
well-ordered monolayers on metal and semiconductor surfaces, thiols received extensive
attention during the last two decades. Since the most potential devices require connecting by the
both ends of a molecule (or molecular film) to electrodes, dithiols deserve special consideration
because they have been found to attach to substrate only through one sulfur. Therefore, they can
provide a convenient tool for attaching active materials or inserting particular species (ions,
molecules or metal particles) onto a surface. Among them there are the so-called Au-monolayer
protected clusters (Au-MPCs), which are very small clusters of gold atoms (5 nm average core
diameter), coated with thiolate monolayers. For the studying these phenomena we have prepared
the p-GaAs (1 0 0) electrodes (mounted on Teflon holders) from Zn doped (n = 2.3 × 1018 cm−3)
wafers supplied by AXT Company (GEO Semiconductor (UK) Ltd.). The self assembled layers
of 4,4_-thio-bis-benzenethiolate-protected gold nanoparticles (Au- MPCs) were built from
ultrasonic dispersed Au-MPCs powder in anhydrous ethanol solutions. Au-MPCs were prepared
by the two-phase synthesizing method by using 4,4_-thio-bis-benzenethiol (TBBT) instead of
dodecanethiol. The microstructure of the Au- MPCs samples was investigated using a JEOL 200
CX TEM operating at an accelerating voltage of 200 KV (fig.1).
145
Fig.1TEM image of Au-MPCs particles
Particle sizes were measured from bright and dark field images. AFM experiments were carried
out in air by using the Dynamic Force Module of an EasyScan2 model from Nanosurf® AG
Switzerland operating in the intermittent contact mode. The fractal analysis of the AFM images
taken for the bare-, TBBT- and Au-MPCs-covered p-GaAs (1 0 0) substrates was carried out
after the elimination of the background electronic noise . XPS spectra were obtained with a
SPECS spectrometer (Fig.2) equipped with monochromatized Al K anode radiation source
operated at 400 W. The electrochemical measurements were performed in 0.1 M phosphate
buffer pH 7.5 with an IM-6 Zahner frequency analyser in
Fig.2 S-2p core-level region for p-GaAs (100), TBBT/ p-GaAs (100) and Au-MPCs/ p-GaAs (100)
the range of 0.3 Hz–300 kHz. The impedance spectra were fitted using Zview software (Scribner
Associates Inc., Southern Pines, N.C.). All potentials refer to saturated calomel electrode (SCE).
The impedance data were analyzed by using the serial connection of the electrical contributions
of the semiconducting electrode shown in Fig.3, which gave the best fit of the experimental data.
146
Fig.3 Mott–Schottky plots for p-GaAs (100) TBBT/p-GaAs (100) and Au-MPCs/ p-GaAs (100)
The SHG set-up is essentially the same as
described previously [1]. The measurements were performed in the p-in/p-out configuration by
using the fundamental output (1064 nm) from a Q-switched Nd:YAG laser operating at 20 Hz
with 9 ns pulse width, incident at an angle of 45◦ on the sample. The TEM analysis clearly show
isolated metal nanoparticles without aggregation. Gold nanocrystals are distributed in zones,
forming high and low density regions, and in some areas they may also aggregate in chains. The
XPS and AFM results revealed a well-ordered overlayer exhibiting a bi-modal highly correlated
fractal behavior which, however, cannot electrode.fully protect the oxidation in air. The EIS data
pointed out the influence exerted by the gold-monolayer protected clusters (Au-MPCs) over the
charging/discharging processes observed at p-GaAs (1 0 0). Although the applied potential is
varied linearly, the semiconducting surface against the potential drop within the semiconductor
space charge region as well as that across the Au-MPCs layer undergoes stepped changes
supposed to result in the discrete charging of the Au-MPCs. These effects point to an electronic
equilibrium between the Au-MPCs and the semiconducting substrate. Fermi level pinning and
enhancement of the SHG response in the potential range where the surface/interface states in the
semiconductor band gap become electrically active bring further proof in this respect. Our
previous studies revealed that 4,4_-thio-bis-benzenethiolate film spontaneously formed on pGaAs (100) surfaces brings about chemical passivation, both in air and in solution as well as
strong adsorbate–substrate interactions which affect both the semiconductor surface state
population and the field effects operating in the interfacial region . Now we report the selfassembling effects of Au nanoparticles protected by 4,4_-thio-bis-benzenethiolate at p-GaAs
(1 0 0) electrodes [2].
References
[1] V. Lazarescu, R. Scurtu, M.F. Lazarescu, E. Santos, H. Jones, W. Schmickler, Electrochimica Acta 50 (2005)
4830.
[2] M. Enache, L. Preda, C. Negrila, M. F. Lazarescu, I. Mercioniu, E. Santos, M. Anastasescu, G. Dobrescu, V.
Lazarescu , Electrochimica Acta, 77, ( 2012) 8
147
Infrared Dichroism Studies on Poly(p‑phenylenevinylene)/Single-Walled
Carbon Nanotube Composites
M. Baibarac, I. Baltog,
in cooperation with
J. Wery, S. Lefrant, J. Y. Mevellec
Institut des Materiaux “Jean Rouxel, Nantes, France
Special attention given in the past decade to carbon nanotubes (CNTs) noncovalently
functionalized with poly(p-phenylene-vinylene) (PPV) is motivated by the multiple applications in the
fields of solar cells, organic photodiodes, organic thin-films transistors, photovoltaic devices, and
photodetectors. As is shown in this paper, the layout of polymers and composites as thin films onto SERS
active metallic supports, i.e., Au and Ag, creates new opportunities for studying the molecular orientation
by FTIR spectroscopy in the grazing angle incident reflection geometry. Only three articles are devoted to
infrared dichroism studies on composites and these are focused on composites based on multiwalled
carbon nanotubes functionalized with polystyrene and styrene−butadiene copolymers [1]. The
dependence of the FTIR spectra recorded in the grazing angle incident reflection geometry of the PPV
film as a function of the
concentration of SWNTs in composites mass is investigated . For a better understanding of the
functionalization process of SWNTs with PPV, new details concerning the changes induced in the
molecular orientation of the PPV film by the addition of SWNTs to the precursor solution are need to be
known. They are found by using FTIR spectroscopy in the grazing angle incident reflection geometry [1].
Given that our samples consist of thin films deposited onto rough Ag and Au supports, an evaluation of
the influence of the metallic support on PPV without SWNTs is necessary. Fig. 1 shows the FTIR spectra
of PPV in polarized light as a function of the type of metallic support.
148
Fig. 1 FTIR spectra of the PPV film with a thickness of ca. 200 nm deposited on Ag and Au supports
recorded in the grazing angle incident reflection geometry with p and s polarizations [1]
According to previous FTIR studies, the main absorption FTIR bands are situated at ca. 835, 966,
1059−1109, 1267−1334, 1421 −1423, 1516, and 1601−1691 cm−1 and are associated with the following
vibrational modes: phenyl ring C−H out-of plane bending, trans-vinylene C−H out-of-plane bending,
C−H in-plane bending, carboxyl stretching, phenyl ring C=C in plane in-plane ending, phenyl ring C−C
in-ring stretching, and CO stretching, respectively. The first two vibrational modes are perpendicular to
the plane of the PPV chains, while the latter three modes are parallel to the plane of the PPV chains. The
absorption FTIR band with the maximum at 1691 cm−1,which is assigned to the carbonyl stretching
vibration mode is observed only in the case of the PPV film deposited on Au support. The absence of this
band in the case of FTIR spectra of the PPV films deposited on Ag supports indicates that the annealing
treatment does not lead to the creation of oxygenated defects in the macromolecular chain. This difference
observed in the case of PPV films deposited onto Ag and Au supports can be explained by the affinity of
oxygen for the Ag support when the formation of an Ag2O layer occurs. In the case of Au support, which
is a metal that does not have an affinity with oxygen even at high temperature, the lack of a covering
oxide layer permits direct interaction of oxygen sources with the macromolecular chain, generating new
functional groups of the type C=O.As observed in Fig.1, the intensities of the absorption bands peaked at
835 and 966 cm−1 strongly depend on the angle of polarization. This fact indicates a preferential
orientation of the polymer chain in the plane of the film. In the case of s polarization, these bands vanish
partially or totally when the PPV film is deposited on Ag and Au supports, respectively. Regardless of the
149
type of metallic support, the two absorption bands for p polarization appear the strongest. For the FTIR
absorption bands with maxima situated at 1421 and 1516 cm−1, which are associated with vibration modes
of the C=C in-plane bending and C−C in-ring stretching of the phenyl ring, respectively, a dependence on
polarization is noted only in the case of Ag support. Other differences observed in Fig.1 concern the ratio
between the relative intensities of the FTIR absorption bands with maxima at 964 and 1516 cm−1 when the
FTIR spectra of PPV are recorded in the following geometries: (i) in the s polarization geometry, when
the electric field vector E is parallel to the film plane, the values for the ratio I964/I1516 in the case of Ag
and Au supports are 1:2.2 and 1:7.5, respectively; and (ii) in the p polarization geometry, when the
electric field vector E is perpendicular to the film plane, the values of the ratio I964/I1516 in the case of Ag
and Au supports are 6:1 and 1:1, respectively. These differences must be correlated with the absorption of
PPV molecules onto the metallic surface. Fig.2 shows the influence of the amount of SWNT added to the
PPV precursor solution on the FTIR spectra recorded in the grazing angle incident reflection geometry
with Ag and Au supports.
Fig. 2 FTIR spectra of the PPV film with a thickness of ca. 200 nm deposited on Ag and Au supports
recorded in the grazing angle incident reflection geometry in the polariza-tion, obtained in the absence
and presence of different SWNTs weight percentages equal to 64 and 32 wt %.[1]
This difference results from the functiona-lization process of SWNTs with PPV, when a π−π*interaction
between the sidewall of the CNTs with the phenyl rings of the PPV occurs. A result of this interaction is a
modification of the angle of the transition dipole moment vector for the phenyl ring C−H in the out-of
plane vibrational mode [1].
150
References
[1] M.Baibarac, I.Baltog, J.Wery, S. Lefrant, J. Y. Mevellec, J. Phys. Chem. C 116, 25537
(2012).
Photoexpansion and nano-lenslet formation in amorphous As2S3 thin films by
800nm femtosecond laser irradiation
A. Velea, M. Popescu, F. Sava, A. Lőrinczi, I. D. Simandan
in cooperation with
G. Socol, I. N. Mihailescu, N. Stefan, F. Jipa, M. Zamfirescu
National Institute for Laser, Plasma and Radiation Physics, Bucharest-Magurele, Romania
A. Kiss, V. Braic
National Institute for Optoelectronics, Bucharest-Magurele, Romania
As2S3 films were prepared on glass substrate by PLD using a KrF* laser source (λ = 248 nm, τFWHM =
25 ns, model COMPexPro 205, Lambda Physics-Coherent). The targets were irradiated with a laser
fluence of 1.5 J/cm2 and the repetition rate was 10 Hz. The depositions were carried out at room
temperature while the pressure of the residual gas inside chamber was 4×10-4 Pa.
Homogeneous films with thickness of around 2 µm were grown at target-substrate separation
distance of 4 cm by applying 11 000 subsequent laser pulses. A standard laser micro-processing setup was
used for producing microstructures on As2S3 film. The laser source was a femtosecond oscillator Synergy
Pro with 800 nm central wavelength, 15 fs pulse duration, 80 MHz repetition rate, and 5 nJ maximum
energy per pulse.
Atomic force microscopy investigation was conducted with an INNOVA (Veeco) instrument. The
microscope was vibration-damped. Commercial pyramidal phosphorus doped silicon tips (Veeco model
RTESPA) mounted to a cantilever with a length of 125 µm were used. The resonance frequency and a
nominal force constant were 332.6 kHz and 40 N/m, respectively. To avoid damage of the sample, the
measurements were carried out in tapping mode. The scan speed was 8 µm/s (0.4 Hz) for the 10×10 µm2
images.
151
Images were obtained by displaying the height signal acquired in forward direction at 512×512
pixels image resolution.
Fig. 1 10×10 µm AFM images of laser
irradiated areas: (a) 8 mW,(b) 12 mW, (c) 18
mW, (d) 20 mW, (e) 25 mW, (f) 30 mW, (g) 50
mW.[1]
For low laser powers (2–6 mW), the surface
of the thin film was not altered. Figures 1(a)–1(g) show the sequence of three-dimensional
images of the imprinted areas on the film of As2S3. One observes that when increasing power of
the laser the profile of the imprints changes dramatically. At lower laser power (Figs. 1(a)–1(d),
from 8 to 20 mW), hillocks are formed in the irradiated area of As2S3 film as a result of
photoexpansion effect. Figure 2 shows the evolution of the hillock height and hole depth as well
as the variation of the hillock and hole diameter with the laser power.
This is in good agreement with the observation of Tanaka et al. [2]. At higher laser power (Figs.
1(e)–1(g)), the laser beam
0.4
3
4
3.6
7
5
1
0.0
3.2
1: 8 mW
2: 12 mW
3: 18 mW
4: 20 mW
5: 25 mW
6: 30 mW
7: 50 mW
-0.4
-0.8
5
2.8
6
2.4
6
Diameter (µm)
Height/Depth (µm)
Hole
Hillocks
2
4
2
3
2.0
-1.2
7
1
1.6
0
10
20
30
40
50
P (mW)
Fig. 2 Variation of the height/depth and diameter of the hillocks/holes with the power of the laser.[1]
induces in the center of the irradiated area holes that deepen and enlarge proportional with the increase of
the laser power. In the case of the highest laser power (50 mW), the ablation process dominates.
152
The hillocks have an asymmetric double sigmoidal shape and their height depends on the power of the
laser. The maximum height of 210 nm is obtained at a laser power of 18 mW. Such geometrical shapes
can be used as special lenslets in the planar geometry of optical circuits.
The diameter of lenses increases with the laser power. Cross-sections through different nano-lenslets
obtained at various laser powers can be seen in Fig. 3.
According to the cluster model, the photoexpansion of As2S3 glass [3] can be asymmetrical due to
larger expansion along the direction of the laser beam and because of the orientation of the package of
clusters during this process. The asymmetry could also be related to the anisotropy [4, 5] induced by laser
light.
The optical properties of the nano-lenslets are strongly related to the chalcogenide composition. In
general, during laser irradiation the chalcogen element is easily released from the bulk or from the thin
film.
Fig. 3 Cross section profiles of the chalcogenides imprinted nano-lenslets. At higher laser power a hole
with increasing depth and diameter appears in the middle of the impact zone, as visible in the last three
profiles.[1]
In particular, the arsenic trisulphide material (As2S3, orpiment) tends to change into As2S2 (realgar). At
high laser power, the composition modification seems to be significant and some sulphur is released. The
X-ray diffraction diagrams of the films irradiated by laser show the presence of realgar (As2S2). The high
power irradiation also determines the rapid release of the chalcogen from the chalcogenide material.
Sulphur is partially eliminated and a definite hole appears in the irradiated area. With the increase of the
power of the laser, the diameter of the hole and its depth increase significantly (see Fig. 3).
References
153
[1] A. Velea, M. Popescu, F. Sava, A. Lőrinczi, I.D. Simandan et al., J. Appl. Phys. 112, 033105 (2012).
[2] Ke. Tanaka, Phys. Rev. B 57, 5163 (1998).
[3] M. Popescu, F. Sava, and A. Lőrinczi, J. Non-Cryst. Solids 355, 1815 (2009).
[4] V. Lyubin, M. Klebanov, S. Rosenwaks, and V. Volterra, J. Non-Cryst. Solids 164–166 (Part 2), 1165
(1993).
[5] A. Kolobov, V. Lyubin, T. Yasuda, M. Klebanov, and Ke. Tanaka, Phys.Rev. B 55, 8788 (1997).
Effects of TiO2 nanoparticles on the NO2- levels in cell culture media analysed
by Griess colorimetric methods
T. Popescu, L. Diamandescu, D. Tarabasanu-Mihaila, V. S. Teodorescu, A. M. Vlaicu
in cooperation with
A. R. Lupu
University of Bucharest, Faculty of Biology, Bucharest, Romania
and
V. Raditoiu, V. Purcar
National Research and Development Institute for Chemistry and Petrochemistry – ICECHIM, Bucharest,
Romania
The Griess assay [1] has been used to determine the possible changes in the measured NO2concentrations induced by TiO2 nanoparticles in three types of nitrite-containing samples: aqueous
NaNO2 solutions with known concentrations and two types of cell culture media- Roswell Park Memorial
Institute medium (RPMI-1640) and Dulbecco's Modified Eagle Medium (DMEM-F12) used either as
delivered or enriched in NO2- by NaNO2 addition. We have used three types of titania with average
particle sizes between 10-30 nm: Degussa P25 (P25) and two other samples (undoped (HT) and Fe3+doped anatase (FeHT) TiO2) synthesised by a hydrothermal route in our laboratory. The structural,
morphological, optical and physicochemical characteristics of the used materials have been studied by Xray diffraction (XRD), electron microscopy (TEM, EDX), Mössbauer spectroscopy, Brunauer-EmmettTeller (BET) nitrogen adsorption, UV-Vis reflectance spectroscopy, Dynamic Light Scattering (DLS) and
Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT). The opacity and sedimentation
behaviour of the studied TiO2 suspensions have been investigated by photometric attenuance
measurements at 540 nm. To account for the photocatalytic properties of titania in a biologically relevant
154
context, multiple Griess tests have been performed under controlled exposure to laboratory natural
daylight illumination. The results show significant variations of light attenuance (associated to NO2concentrations in the Griess test) depending on the opacity, sedimentation stability, NO2- adsorption and
photocatalytic properties of the tested TiO2 nanomaterials.
These findings identify material
characteristics recommended to be considered when analysing the results of Griess tests performed in
biological studies involving TiO2 nanoparticles.
Results and discussion
In case of media used without NO2- addition, the obtained results [2], consisting exclusively in attenuance
increases (Fig. 1), are dictated by the opacities and sedimentation behaviours of the tested materials. The
high settling rates of the hydrothermal specimens ensures the lack of significant effects of these materials
upon the light attenuances of their supernates measured at 540 nm. The superior suspension stability of
P25 titania leads to considerably enhanced attenuance values with respect to the reference samples for this
type of TiO2. In biological tests, in case of insignificant or no NO production and release in the cell
culture (media with no NO2- addition in this study), such materials may lead to false significant amounts
of NO apparently produced by the cells. This false NO production may be interpreted as immune cells
activation and subsequent inflammatory processes induced by the tested nanomaterials. In case of culture
media enriched in NO2-, the obtained attenuances (Fig. 1) result from the
Fig.1 Griess tests results in DMEM-F12 medium for: (a) P25, (b) HT and (c) FeHT;
155
combined action of multiple factors, involving concentration dependent opacity as well as the kinetics of
sedimentation and photocatalytic/NO2- adsorption processes, under the experimental conditions of this
study [2]. Regarding suspension stability, combined zeta potential and supernate opacity measurements
reveal the suspension stabilizing role of nitrite ions and FBS present in culture media. In cellular tests, if
a significant amount of NO was indeed produced by the activated cells (NO2- enriched media in our
experiments), this amount may appear to be larger due to opacity effects (case of P25 at high
concentrations in our study) or insignificant due to adsorption and photocatalytic processes (case of HT
and FeHT as well as P25 in our study). Consequently, materials with potential inflammatory properties
may be treated as inert and nontoxic and possibly recommended for biocompatible applications (e.g. to be
used as food additives or pharmaceutical excipients).
The occurrence of significant interferences between TiO2 and the Griess assay ultimately depends on
the existing interactions between TiO2 nanomaterials and culture media. Some of these interactions may
exhibit multiple consequences upon the factors (sedimentation, adsorption and photocatalysis) dictating
the attenuances of the samples analysed by the Griess method. Protein adsorption, for example, promotes
suspension stability leading to opacity mediated attenuance enforcement and inhibits the NO2- adsorption
and its photocatalytic oxidation by hindering the TiO2-NO2- interactions. These processes (NO2adsorption and photocatalysis) may also be inhibited by the competing adsorption of culture media
phosphate onto the TiO2 surfaces. Other photocatalysis inhibiting factors are light absorption by culture
media and particle agglomeration effects.
Acknowledgements
The support of the Romanian National Authority for Scientific Research, under the Core project PN09450102, is greatly acknowledged.
The final publication is available at http://link.springer.com/article/10.1007%2Fs11051-013-1449-0
References
[1] J. Sun, X. Zhang, M. Broderick, H. Fein, Sensors, 3, (2003), 276-284.
[2] T. Popescu, A.R. Lupu, L. Diamandescu, D. Tarabasanu-Mihaila, V.S. Teodorescu, V. Raditoiu, V.
Purcar, A.M. Vlaicu, Journal of Nanoparticle Research, 15, (2013), 1449.
156
Potential Applications
157
Surface and bulk radiation induced defects in Si-based sensors
I. Pintilie and R. Radu in collaboration with
J. Zhang, E. Fretwurst, R. Klanner, H. Perrey, J. Schwandt and G. Lindström
Institute for Experimental Physics, University of Hamburg, Hamburg, Germany
This work had been triggered by the challenge presented by the Large Hadron Collider (LHC) at the
European Nuclear Research Centre CERN and its planned upgrade (SLHC) foreseen now to start in 2020,
by the International Linear Collider (ILC) or by the high brilliance photon sources like XFEL foreseen to be
operational in 2014. Silicon detectors are increasingly in use for various applications in fundamental
research such as elementary particle and nuclear physics and research with photons or radiation in free
electron lasers. The limiting factors for their practical application are the radiation induced changes in
their electrical properties. In this work two cases are considered: (i) the bulk radiation damage caused
by hadrons in LHC experiments and responsible for the increase of the dark current and (ii) interface
effects caused by X-ray in MOS structures for XFEL experiments leading to the generation of oxide
charge and annealing effects:
(i) Bulk radiation damage resulting from the non-ionizing energy loss (as e.g. in LHC/SLHC)
The main radiation induced deep defect centres in silicon responsible for the changes in the electrical
properties during and after the irradiation are: the Ip, BD, E(30K) and H(116K), H(140K), H(152K),
responsible for the change in the depletion voltage and the E4, E5 and E205a defects responsible for the
increase of the dark current and the corresponding noise [1]. The two deep acceptor levels E4 at Ec 0:39 eV and E5 at EC - 0:45 eV evidenced in Fig. 1a have been proven to be the doubly and the singly
charged state of the tri-vacancy (V3). At temperatures above 200 0C and depending on the oxygen
concentration of the material, the V3 transforms into the tri-vacancy–oxygen complex (V3O) – defect L
in Fig.1b. This identification is based on the striking similarity of the reaction E5-L to the known
transformationV2-V2O and the significant oxygen dependence of the generation of the L defect. As a
result, the L defect can be assigned to the V3O complex. The defect concentrations were obtained by
means of Deep Level Transient Spectroscopy (DLTS) and Thermally Stimulated Currents (TSC) techniques
performed on float zone (FZ), epitaxial (Epi) and Magnetic Czochralski (MCZ) diodes, irradiated with
1MeV neutrons and 23 GeV protons.
158
Fig.1. a) Concentration of E4 and E5 defects as result of the difference between the DLTS spectra at an
annealing step of 240 °C and the successive injection of 20 min with 1 A in FZ material,
. b) Annealing of E5 compared to the V2 defect for MCz material.
b) Surface and interface related effects in MOS structures [3-5] caused by ionization in environments
with 12 keV X-ray doses up to 1 GGy (as e.g. in XFEL). The aim of this work is to (1) understand the
radiation damage induced by X-rays, (2) extract the damage-related parameters, i.e. the surface density
of oxide charges and surface-current density, which are the main inputs for sensor optimization with
TCAD simulation, (3) investigate the effects due to the voltage applied to the gates of the MOS capacitor
and the gate-controlled diode during irradiation, and (4) verify the long term stability and performance
of silicon sensors with the help of annealing studies. The techniques used are Capacitance/ConductanceVoltage (C/G-V) for different frequencies and Thermal Dielectric Relaxation Current (TDRC). In addition
to radiation induced oxide charges, at least three dominant interface traps have to be used to describe
the measurements as given in Fig.2.
Fig. 2. The shapes of the three dominant interface trap levels caused by X-rays in MOS capacitors as function of
their position in the silicon band gap.
159
Fig.3. Dose dependence of the fixed oxide charge density Nox and the three dominant X-ray induced
interface states as function of irradiation dose after annealing at 80 °C for 10 minutes.
Fig. 4.Measured and calculated C-V and G-V curves (parallel mode) of a MOS capacitor irradiated to 10 MGy
(12 keV X-rays) for frequencies between 1 and 100 kHz (a) C-V curves, (b) G-V curves.
Their properties and densities as function of X-ray dose have been determined. The oxide charge density
and the trap densities saturate and for one interface state even decrease at dose values between 10 and
100 MGy (Fig.3). The shape of the C/G-V curves can be described by a simple model with parameters
derived mainly from the TDRC measurements [3] as they are given in Fig.4. Finally, annealing studies
have been performed at 60 0C and 80 0C on MOS capacitors and gate-controlled diodes irradiated to
5MGy and the annealing kinetics of oxide charges and surface current determined [5]. These parameters
are presently implemented in a simulation program to check if the performance of segmented sensors
as a function of X-ray dose can be described and if the results can be used to design radiation hard
silicon sensors for XFEL.
References
[1] I. Pintilie, "Surface and bulk radiation induced defects in Si-based sensors", invited talk 1st
Conference on Radiation and Dosimetry in Different Fields of Research (RAD2012), 24-27 Aprilie 2012,
Nis, Serbia.
160
[2] A. Junkes, I. Pintilie, et al., PHYSICA B-CONDENS. MATTER , 407, 3013-3015, 2012
[3] J. Zhang, I. Pintilie, et al., J. SYNCHROTRON RADIAT., 19, 340-346, 2012
[4] J. Schwandt, E. Fretwurst, R. Klanner, I. Pintilie, J.Zhang, J. INSTRUM. 7, C01006, 2012
[5] J. Zhang, E. Fretwurst, R. Klanner, I. Pintilie, et al., J. INSTRUM., 7, C12012, 2012
Effect of interfaces on electric properties of ferroelectric-based structures
L. Pintilie, G. A. Boni, C. Chirila, L. Hrib, A. Iuga, I. Pasuk, R. Negrea, L. D. Filip
in collaboration with
E. Vasile,
METAV-C.D.S.A., Rosetti Street No. 21, Bucharest 020011, Romania
and
H. Khasaff, I. B. Misirlioglu
Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, 34956 Istanbul, Turkey
The effect of interfaces on the electric properties of several ferroelectric-based structures was
investigated. The structures are: BiFeO3 (BFO) layers doped with Gd atoms, deposited by sol-gel on
single crystal Nb doped SrTiO3 (STON) substrates with (001) orientation, and with top Pt contacts
(Pt/Gd:BFO/STON); metal-ferroelectric-metal (MFM) structures based on epitaxial Pb(Zr0.2Ti0.8)O3 (PZT)
grown by pulse laser deposition (PLD) on single crystal SrRuO3/SrTiO3 (SRO/STO) substrates with (001)
orientation and with different metals used as top electrode (metal/PZT/SRO, where the metal is SRO, Cu
or Pt); metal-ferroelectric-semiconductor (MFS) structures based on PZT and ZnO layers grown by sol-gel
or PLD on Pt/Si and SRO/STO substrates and with top Pt electrodes (Pt/ZnO/PZT/Pt or SRO as bottom
electrode).
In all cases it was found that the interfaces have a significant impact on the electrical properties of the
investigated structures. The main results are presented below.
1.In the case of the Pt/Gd:BFO/STON it was found that current-voltage (I-V) characteristic is asymmetric,
resembling the behaviour of a p-n diode (see fig. 1). Analysing the I-V measurements performed at
different temperatures it was concluded that the most probable conduction mechanism is the SchottkySimmons emission over the potential barrier at the Gd:BFO/STON interface, where the charge injection
is controlled by the barrier properties and the drift is controlled by the bulk of the ferroelectric film
161
through the charge mobility. The height of the potential barriers was estimated and it was found that it
is dependent on the Gd content: 0.32 eV at zero doping; 0.45 eV for 5% Gd doping; 0.60 eV for 10% Gd
doping. Other quantities were also dependent on the Gd doping: the built-in potential and the
concentration of the free carriers [1].
Fig. 1 I-V characteristics at RT for different Gd doping of the BFO layer.
2.The change of the metal used as top contact in the case of the metal/PZT/SRO structures produces
important changes in the hysteretic behavior of the ferroelectric polarization. It has to be underlined
that the metals used as top contacts (Cu, Pt and SRO) were deposited successively on the same epitaxial
PZT film grown on the bottom epitaxial SRO electrode. Therefore, the quality of the film and of the
bottom PZT/SRO interface is the same in all cases. Only the properties of the top metal/PZT interface
can be different, depending on the metal used as top electrode (see fig. 2). It was found that the best
results are obtained with top Cu, with rectangular hysteresis and negligible leakage current. When Pt is
used as top electrode the leakage current increases and the hysteresis loop become inflated. This result
is puzzling, considering that Pt has a work function with about 1 ev higher than Cu. Also, another
interesting result is that, although only the top electrode is changed, the electronic properties of the
bottom PZT/SRO interface seems to be also affected, maintaining the relative symmetry of the loops [2].
162
Fig. 2 Dynamic hysteresis loops (current and polarization) recorded for the high quality epitaxial PZT film
with: (a) top Cu electrode; (b) top SRO electrode; and (c) top Pt electrode. All the measurements were
performed at 1000 Hz with a triangular voltage wave.
3.In the case of Pt/ZnO/PZT/Pt(SRO) MFS structures it was found that the temperature where the
direction of the capacitive hysteresis changes from clockwise to counter-clockwise[3] is strongly
dependent on the quality of the ZnO/PZT interface. The higher is the quality of the interface, with lower
density of interface states, the lower is the temperature where the capacitive hysteresis is changing its
orientation. The best interface quality is obtained in the case of PLD grown ZnO/PZT heterostructure on
SRO/STO substrate (see fig. 3). The epitaxial growth leads only to counterclockwise hysteresis on the
entire investigated temperature range from 100 K to 400 K [4].
163
Fig. 3 HRTEM images of (a) multilayered STO/SRO/PZT structure (inset—FFT pattern of the image (a)
revealing the epitaxial growth of the layers on the STO (001) substrate), (b) STO–SRO interface, (c) SRO–
PZT interface, and (d) PZT–ZnO interface.
Funding from CORE program PN09-45 [1]; FP7 project IFOX (grant number 246102); CNCSIS Project “RP” Grant No. 1/28/2010
[2]; Contract No. PCCE 3/2012 [4].
References
[1] H. Khassaf, G. A. Ibanescu, I. Pintilie, I. B. Misirlioglu, and L. Pintilie, Appl. Phys. Lett. 100, 252903
(2012)
[2] L. Pintilie, I. Pasuk, R. Negrea, L. D. Filip, and I. Pintilie, J. Appl. Phys. 112, 064116 (2012)
[3] L. Pintilie, C. Dragoi, R. Radu, A. Costinoaia, V. Stancu, and I. Pintilie, Appl. Phys. Lett. 96, 012903
(2010)
[4] I. Pintilie, I. Pasuk, G. A. Ibanescu, R. Negrea, C. Chirila, E. Vasile, and L. Pintilie, J. Appl. Phys.
112, 104103 (2012)
164
Polysaccharide – iron oxide nanostructures for biomedical applications
Carmen StelutaCiobanu, Simona Liliana Iconaru, Daniela Predoi
in collaboration with
MihaelaRadu, AncaDinischiotu,
Department of Biochemistry and Molecular Biology, University of Bucharest, 050095, Bucharest,
Romania
AlinaMihaelaProdan
Emergency Hospital Floreasca, Bucharest 5, CaleaFloresca nr 8, sector 1, Bucarest, Romania
Mikael Motelica-Heino, Stanislas Sizaret
ISTO, Université d’Orléans, 45067 Orléans cedex 02, France
Philippe Le Coustumer
Université Bordeaux 3, EA 4592 G&E, EGID
and
Khalid Lafdi
University of Dayton, 300 College Park, Dayton, Ohio 45469, USA
Iron oxide, magnetite (Fe3O4) and its oxidized form maghemite (γ-Fe2O3) are the most studied
magnetic particles in medicine and biotechnology because of their unique magnetic properties and
biocompatibility at nanometric scale [1-2]. The polysaccharide (dextran, sucrose) coated iron oxide
nanoparticles were synthesized by adapted co-precipitation method [1-3].
The diffraction pattern of DIO-NPs (dextran iron oxide nanoparticles) and SIO-NPs (sucrose iron
oxide nanoparticles)[2-4] shows the peaks that correspond to an fcc cubic maghemite structure (ICSD
card no.01-083-0112) characterized by diffraction planes (220), (311), (400), (422), (511) and (440). No
additional diffraction peaks of any impurity were detected, demonstrating the high purity of the
synthesized samples. The average sizes, deduced from the full width at half maximum, has a value of 5.8
(± 0.5) nm for DIO-NPs and 7.3 (± 0.5) nm for SIO-NPs. They are consistent with the mean sizes
deduced from HR-TEM observations [2-5].
The antibacterial activity of the samples (DIO-NPs and SIO-NPs) were observed using common
bacterial pathogens, E coli, P aeruginosa (gram negative), E Faecalis (gram positive) and a species of
fungus (C krusei). The antibacterial effect of DIO-NPs on the Gram-negative bacteria E. coli ATCC
25922 was less visible than that on the Gram-positive bacteria E faecalis ATCC 29212 and C krusei 963
(a species of fungus) for all concentrations. DIO-NPs showed highly significant toxicity to all three
bacterial species (Figure 1). The Gram-negative bacteria P aeruginosa 1397 is not inhibited in presence of
DIO-NPs. Concerning the effect of DIO-NPs on the microbial growth of the tested strains, we could
observe that different concentrations of the tested compound either inhibited or stimulated the growth of
E. faecalis ATCC 29212, E coli ATCC 25922, C krusei 963strains in suspension. On the other hand, in our
study the SIO-NPs proved to stimulate the growth of microbial cells, as demonstrated by the absorbance
measurements at 620 nm of the obtained cultures (Figure 1). The intensity of the stimulatory effect on the
microbial growth proved to be proportional with the concentration of SIO-NPs, as proved by the linear
trend lines. In exchange, all tested concentrations of DIO-NPs and SIO-NPs slightly stimulated the
growth of P. Aeruginosa 1397.
Antimicrobial activity of the DIO-NPs and SIO-NPs are influenced by the polysaccharide type and the
size of the particles. The bacteria sensitivity to each type of NP also varied with the bacterial strain. The
antibacterial activity of PMC-NPs based on dextran was significantly higher than that observed against
PMC-NPs based on sucrose for E faecalis ATCC 29212, C krusei 963 and E coli ATCC 25922.
165
Fig. 1. Antibacterial activity of DIO-NPs and SIO-NPs in the presence of E. coli ATCC 25922, E faecalis ATCC 29212, C krusei
963 and P aeruginosa 1397.
Our previous data proved a good viability of Hep G2 cells grown on dextran powder [6] as well
as dextran coated maghemite thin films. Also, no changes in cells morphology were noticed under phase
contrast microscopy [2]. The dextran-iron oxide continuous thin films obtained by MAPLE technique
from composite targets containing 10 wt.% dextran as well as 1 and 5 wt.% iron oxide nanoparticles
synthesized by co-precipitation method presented granular surface morphology. This represented an
advantage in the adhesion and growth of living HepG2 cells. Our results proved that Hep G2 cells
adhered very well to thin films of dextran (coated with 1% and 5% maghemite) and exhibited a normal
actin cytoskeleton, which suggest that these cells underwent normal cell cycle progression. As a result,
hepatocytes adhered to these thin films could be used as biosenzors for different xenobiotics.Actins are
highly conserved proteins that are ubiquitously expressed in all eukaryotic cells. F-actin microfilaments
are essential for the maintenance of cell shape and permeability of tight junctions [2]. Figure shows that,
after 24 hours of cultivation, the expression of F-actin in Hep G2 cells adhered on dextran nanoparticles
thin films (B) and dextran coated 1% maghemiteγ-Fe2O3 (C) was similar and less than in control cells.
Fig.2. The localization of F-actin in HepG2 cells. The cells were cultured for 24h stained first for F-actin with phalloidin (A1-control cells, B1cells cultivated on thin films of dextran, C1- cells cultivated on thin films of dextran coated 1% maghemite nanoparticles, D1- cells cultivated on
thin films of dextran coated 5% maghemite nanoparticles), then incubated with DAPI for the detection of nuclei (A2, B2, C2, D2) and examined
by fluorescence microscopy. A3, B3, C3, D3 images represent the previous images superimposed. The images shown are representative for five
independent experiments.
In the case of cells cultivated on dextran coated 5% maghemiteγ-Fe2O3 (D1), the number of cells
and the level of F-actin were lower compared to the other two types of thin films and control. After 24
hours, the F-actin distribution in the cells from the thin films was especially around the nuclei. Later on,
at 72 hours after the cells cultivation there was no significant difference between the three experimental
alternatives from the point of view of cell numbers and F-actin expression [2].
166
References
[1]. Prodan D, Chaneac C, Tronc E, Jolivet JP, Cherkaour R, Ezzir A, Dormann JL,J MagnMagn
Mater1999, 203: 63-65.
[2] Ciobanu CS, Iconaru SL, Gyorgy E, Radu M, Costache M,Dinischiotu A, Le Coustumer P, Lafdi K,
Predoi D, Chem Cent J, 2012 6:17.
[3]. Iconaru SL, Prodan AM, Motelica-Heino M, Sizaret S, Predoi D, Nanoscale Res Lett, 2012, 7:576.
[4]. Iconaru SL, Ciobanu CS, Le Coustumer P, Predoi D,J Supercoond Nov Magn 2012, 25(8).
[5].Elliott SR, Physics of Amorphous Materials, Longman, London, 1984, 350.
[6].Iconaru SL, Ciobanu CS, Prodan AM, Predoi D, FEBS Journal 279 (Suppl. 1) (2012) 52–576.
XPS and HRTEM investigations of titania-supported gold catalysts used in
heterogenous amination of bromobenzene with aniline
C.M. Teodorescu, F. Vasiliu
in cooperation with
M. Ciobanu, B. Cojocaru, S.M. Coman, V.I. Parvulescu
Faculty of Chemistry, University of Bucharest, Romania
S. Wuttke
Department of Chemistry, University of Munich (LMU), Germany
W. Leitner
Department of Technical Chemistry and Petrochemistry, RWTH Aachen, Germany
Buchwald-Hartwig amination consists in C-N coupling and is a reaction with a huge amount
of applications in organic syntheses [1]. Early studies used Pd cata-lysts to intermediate these
reactions [2]. However, there are some drawbacks of Pd (and also of other transition metals)
catalysis, especially that, even in ppm concentrations, the final compounds are shown to contain
residual amounts of catalysts. Also, Pd catalysts have shown to have short lifetimes, they tend to
aggregate and to form Pd-black nanoparticles [3].
The aim of this study is to promote an alternate route for the amination reaction by using
gold catalysis, especially Au nanoparticles. These catalysts will be used in order to subtract a
proton from the amine and to promote its reaction with the aryl-halide in organic solvents, such
as dimethyl carbonate (DMC), such as described in Scheme 1 [4]. The use of an inorganic base
(potassium etoxide) leads to a more complicated reaction pathway, yielding formation of
diphenylamine and triphenylamine, until the surface of the catalyst is completely covered by
KBr, as was evidenced by XPS measurements [4]. However, this is the only drawback of this
167
mechanism, and KBr can be conveniently removed by using dioxane. Hence, the catalyst can be
recycled several times.
Transmission electron microscopy was used to assess the Au nanoparticle average sizes and
distributions (Fig. 1, Table 1). It is found that larger nanoparticles are formed when the Au
content is close to 1 wt %. (Fig. 1b). Also, some of chemical selectivities decrease when larger
Au nanoparticles are involved (Table 1). X-ray photoelectron spectroscopy (Fig. 2) was used to
derive the Au0 state, to compute the Au/Ti content and to identify the surface covering by KBr
after the reaction (Fig. 2d). The relevant results concerning the characteristics and the
performances of the catalysts are summarized in Table 1. It may be seen that the catalyst
performances are strongly dependent on the Au load and on the solvent used.
Scheme 1. Amination of bromobenzene with aniline promoted by Au nanoparticles supported on titania in
DMC (from [4]).
a
10 nm
168
b
10 nm
Fig. 1. High resolution transmission electron microscopy images of Au/TiO2 catalysts with 0.1 wt. % (a)
and 0.7 wt. % (b) (from [4]).
Fig. 2. X-ray photoelectron spectroscopy of Au 4f (a), Ti 2p (b) and O 1s (c) core levels.(d) represents the C
1s region, exhibiting also the K 2p lines, for a catalyst used in a KEt-dioxane environment (similar to Ref.
[4]).
Table 1. Results of TEM measurements (average particle sizes) on Au nanoparticles and TiO2 substrates,
relevant data (BE = binding energies) obtained from XPS measurements on Au 4f, O 1s and Ti 2p,
together with selectivities in diphenylamine (DPA), N-methylamine (N-MA), N,N-dimethylaniline (N,NDMA), phenylbenzene (PB), N-benzylidene-amine (N-B-A).
169
Au wt
0.1 % 0.3 % 0.5 % 0.7 % 0.9 %
%
<dAu> (nm)
<dTiO2>
(nm)
0.9%,
spent
8.2
±4.5
-
-
14.3 17.1
±3.0 ±2.4
-
47.4
±10.7
-
-
46.9 47.0
±9.8 ±10.6
-
Ti 2p3/2
BE(eV)
-
458.0 458.2 458.2 458.5 458.5
Au 4f7/2
BE(eV)
-
83.1 83.3 83.3 82.6 83.1
O 1s BE(eV)
-
529.7 529.4 529.5 529.9
530.2
531.7
Selectivities in DMC
DPA
(%)
N-MA
(%)
N,NDMA(%)
-
20
22
25
37
-
-
80
70
62
45
-
-
0
8
13
18
-
Selectivities in KEt + dioxane
DPA
(%)
PB
(%)
N-B-A
(%)
-
0
0
18
22
-
-
16
20
24
38
-
-
84
80
58
40
-
170
References:
[4] A.R. Muci, S.L. Buchwald, Top. Curr. Chem. 219, 131 (2002).
[5] A.S. Guram, R.A. Rennels, S,L, Buchwald, Angew. Chem. Int. Ed. 34, 1348 (1995).
[6] M. Tromp, J.R.A. Sietsma, J.A. van Bokhoven, G.P.F. Van Strijdonck, R.J. van Haaren, A.M.J. van
der Eerden, P.W.N.M. van Leeuwen, D.C. Konigsberger, Chem. Commun. 1, 128 (2003).
[7] M. Ciobanu, B. Cojocaru, C. Teodorescu, F. Vasiliu, S.M. Coman, W. Leitner, V.I. Parvulescu, J.
Catal. 296, 43 (2012).
X-ray photoelectron spectroscopy and Mössbauer investigations of Sn-doped
hydroxilated MgF2 catalysts for cellulose saccharification
N.G. Apostol, V. Kuncser
in cooperation with
A. Negoi, V.I. Parvulescu, S.M. Coman
Faculty of Chemistry, University of Bucharest, Romania
S. Wuttke
Department of Chemistry, University of Munich (LMU), Germany
E. Kemnitz
Institute of Chemistry, Humboldt University of Berlin, Germany
A constant preoccupation of modern chemistry is connected to the production of energy,
fuels and other useful chemicals from renewable biomass [1]. One constant subject of
investigation during the last decade is the degradation of cellulose to glucose using heterogenous
catalysis [2]. The main issue of such reactions is connected to the large size of cellulose
molecules, making difficult their penetration into a mesoporous catalyst. The proposed complete
reaction implies a two-step mechanism: firstly, cellulose undergoes a partial hydrolysis promoted
by Brønsted acids, then, when the oligomers are small enough to penetrate the pores of the solid
material, catalytic saccharification occurs.
Recently, it was demonstrated that a modified sol-gel method was able to synthesize
nanoscopic hydroxilated fluorides with the desired mesoporosity and tuneable properties as
Brønsted or Lewis acids [3]. This method was further applied to synthesize Sn-doped MgF2
catalysts which were proven to be hydrothermally stable, highly active and selective for the
saccharification of cellulose to glucose [4]. These samples were analyzed by X-ray diffraction
(XRD), X-ray photoelectron spectroscopy (XPS) and by 119Sn Mössbauer spectroscopy. The
activity tests were performed in a stirred (1200 rpm) and heated (453 K) mixture of cellulose and
catalysts, with subsequent detection by GC-MS chromatography.
171
It was proven that samples with 10 % SnF4 (introduced in the fluorolytic sol-gel reaction)
exhibited one of the largest selectivities reported to date for this reaction. Only the sulfonated
acid carbon catalysis produced better results to date [5]. These 10 % catalysts have shown also
the largest isomer shifts by Mössbauer spectroscopy and also two well-defined XPS components;
also, XPS derived a considerably higher Sn content at the sample surface (almost 23 %). XRD
have shown for these catalysts only MgF2 lines; for lower amounts of Sn, both SnF4 and MgF2
are obtained, together with lines corresponding to a new magnesium fluorostannate phase.
Therefore, a condition for a high selectivity seems to be the high degree of dispersion of Sn into
the MgF2 matrix, together with the presence of active Sn4+ at the surface of the pores. XPS and
Mössbauer pointed on the presence of Sn+(4-δ), with a different ionization state at the surface of
the mesoporous material. The relative amount of the two different sites of Sn4+ evidenced by
Mössbauer stroscopy (Fig.2) as well as their corresponding hyperfine parameters are presented in
Table 1.
These data lead to the hypotheesis that cellulose degradaton takes place following a
homogenous-heterogenous mechanism: (i) initial partial hydrolisis of cellulose, initiated by tin
fluorides released by the solid material in the reacted medium; (ii) subsequent adsorption of
oligomers into the pore system, where interaction with the active species of the solid catalyst
occurs.
Table 1. Results of X-ray photoelectron spectroscopy (binding energies and relative weight of
components from Fig. 1), Mössbauer spectroscopy (isomer shift IS, quadrupole splitting QS, spectral
concentration from Fig. 2), and of chemical selectivity of cellulose dehydration to D-glucose (S).
SnF4
Conc.
XPS
conc.
3d5/2BE
(eV)
Rel.
weight(%)
IS (mm/s)
QS
(mm/s)
Rel.
1%
5%
10 %
15 %
20 %
100 %
1.63 % 6.51 %
22.66
%
21.80
%
20.01
100 %
%
487.7 484.8
488.1
488.1
488.3 489.5
488.7 487.8
488.9
488.6
488.8 490.1
54
3
56
59
58
57
46
97
44
41
42
43
- 0.22 - 0.23
- 0.29
- 0.30
- 0.28 - 0.17
- 0.36 - 0.30
- 0.36
-0.34
- 0.33 - 0.19
0.72
0.81
0.77
0.71
0.82
0.72
0.26
0.27
0.25
0.27
0.27
0.30
81
66
60
60
62
60
172
area(%)
19
34
40
40
38
40
S(%)
66.2
79.4
87.2
69.6
59.0
53.6
Fig. 1. Sn 3d X-ray photoelectron spectra of MgF2 catalysts with different contents of SnF4.
173
Fig. 2. Mössbauer spectra of MgF2 catalysts with different contents of SnF4. The relative Mössbauer
effect (in %) is shown on the left side.
References:
[8] D.L. Klass, Biomass for Renewable Energy, Fuels, and Chemicals, Academic Press, San Diego,
1998.
[9] D.-M. Dai, L. Deng, J. Li, B. Liao, Q.-X. Guo, Y. Fu, ChemSusChem 4, 55 (2011).
[10]
E. Kemnitz, S. Wuttke, S.M. Coman, Eur. J. Inorg. Chem. 31, 4773 (2011).
[11]
S. Wuttke, A. Negoi, N. Gheorghe, V. Kuncser, E. Kemnitz, V. Parvulescu, S.M. Coman,
ChemSusChem 5, 1708 (2012).
[12]
A. Onda, T. Ochi, K. Yanagisawa, Green Chem. 10, 1033 (2008).
174
Photocatalytic decomposition of pharmaceutical ibuprofen pollutions in water
over titania catalyst
L. Frunza
in cooperation with
J. Choina, H. Kosslick*, Ch. Fischer, G.-U. Flechsig, A. Schulz
University of Rostock, Institute of Chemistry & Leibniz Institute of Catalysis e.V.,
Rostock, Germany
with additional characterization studies by
S. Frunza, C. P. Ganea, F. Cotorobai, L. Diamandescu, F. Ungureanu
in cooperation with
A. Schönhals
BAM Federal Institute for Materials Research and Testing, Berlin, Germany
Photocatalytic abatement of hazardous pharmaceuticals by advanced oxidation processes like
photocatalysis over titanium dioxide (titania) is of the highest interest (e.g. [1]) while removal of
dangerous contaminants from wastewater is still a serious problem. Only few publications deal with the
abatement of these contaminants, most of those considered being dyes.
Using titania catalysts is very attractive for effective degradation of drugs and other harmful
organic pollutants especially under UV–Vis irradiation. Titania is a nonhazardous compound, which is
eco-friendly and does not require any additional chemical. It can be recovered and re-used. Most of the
studies deal with high concentration of pollutants using high catalyst amounts from 0.1 to 1 g/L and 10–
100 mg/L of substrate; only few investigations consider the photocatalytic degradation of
pharmaceuticals at low concentration over titania.
Ibuprofen (IBP) belongs to a class of widely met water pollutants, which is biologically active and
has strong impact on the environment even in small concentrations. This compound occurs in
unchanged form and incompletely metabolized forms. Thus, by-products of ibuprofen, which are
175
present in the aquatic environment in low concentration are still harmful for human and animals. The
occurrence of these side products has been often reported in the literature but only high concentrated
solutions were investigated so far [2].
The aim of this work [3] was to revisit the catalytic properties of titania in order to get precise
information on catalytic performance at low concentration, which is of increasing importance. The antiinflammatory drug ibuprofen was used as model compound at low concentration in water.
Commercially available titania P25 from Degussa has been used as the photocatalyst. It was firstly
activated in air by heating at 100◦C for 2h. The samples were then milled in a mortar. Ibuprofen sodium
salt (IBP-Na) was purchased from Sigma–Aldrich. All solutions were prepared using ultrapure water (see
details in [3]).
The crystallinity and phase composition of the catalyst were checked by powder diffraction
measurements. The position of the band gap was confirmed by solid state UV–Vis spectrometry in
diffuse reflection mode. The catalyst was investigated regarding texture, particle shape and size using
electron microscopy and by nitrogen adsorption/desorption measure-ments. Survey and high resolution
XP spectra (e.g. that in Fig. 1) and FTIR spectra in the reflection diffuse mode were collected [4].
IBU-Na concentration was monitored by measuring the absorbance of the samples in UV–Vis
(particularly at 222 nm). Formation and degradation of the intermediate products of IBU-Na
photocatalysis (at room temperature) was checked by ESI-TOF-MS (details in [3]).
The photocatalytic reaction was carried out in a batch reactor. Different amounts of catalyst
powder were suspended in the aqueous solution of IBP-Na. The reactor was equipped with 4 UV–Vis
solarium lamps (15 W) irradiating with an intensity of 2 mW/cm2 (details in [3]).
Counts
15 Jul 1909
A 530.79 eV 1.29 eV 7118.5 cts
B 531.45 eV 0.99 eV 3066.34 cts
C 532.45 eV 1.34 eV 1905.13 cts
34000
D 533.77 eV 1.24 eV 868.942 cts
30000 Baseline: 536.03 to 528.66 eV
Chi square: 5.88037
26000
A
38000
B
22000
_
18000
C
14000
D
10000
6000
2000
540
536
532
Binding Energy, eV
528
524
Fig. 1 High-resolution oxygen XP spectrum of P25
176
sample; decomposition of the peaks and Shirley
background are included.
The locations of the binding energies for the peaks which create the O(1s) signal (Fig. 1) agree well
with the reported values for bulk oxide (O2−) and hydroxyl (OH−) species (details in [4]).
P25 material consists of nanosized particles with a primary diameter of 10–30 nm. They are
regular round shaped and partly agglomerated. The specific surface area of P25 titania is ca. 54 m2/g.
The particles are not porous.
The catalytic performance of titania P25 in the abatement of IBU pollutions in water has
been investigated in detail: The influence of different reaction conditions such as different
substrate (see Fig. 2) and catalyst concentration and corresponding various catalyst-to-substrate
mass ratios, pH value and additional oxygen supply during the degradation were investigated.
The possibility of catalyst re-use has been also checked (see [3]).
Fig. 2 Relative abatement of IBU-Na in water
during photocatalysis over P25 for different IBPNa concentrations and the same catalyst
amount (10 mg/L) (see ref.[3]).
As expected, the absolute amount of abated IBP increases markedly with growing substrate
concentration (Fig. 2). For example, the percentage removal of IBP after 30 min is 10% (for the
60 ppm solution) and 62% (for the 5 ppm solution), but the absolute amount varies in fact
respectively between 6 mg/L and 3.1 mg/L for these two solutions.
The results show that the IBU pollution can be rapidly oxidized over titania P25 catalyst.
Moreover, it is possible to decrease the catalyst concentration and catalyst-to-substrate mass ratio
for marked savings of catalysts. The abatement is accompanied by the formation of temporary
reaction products which are the source of oligomer or polymer formation by radical reaction
leading to the catalyst deactivation. Enhancement of the intrinsic photocatalytic activity is of
importance and still a challenge.
177
References
[1] O. Carp, C.L. Huisman, A. Reller, Progr. Solid State Chem. 32, 33 (2004).
[2] F. Méndez-Arriaga, R.A. Torres-Palma et. al., Water Research 42, 4243 (2008).
[3] J. Choina, H. Kosslick et al., Appl. Catal. B 129, 589 (2013).
[4] F. Ungureanu, A. Manea et. al., Molec. Cryst. Liq. Cryst. 562, 200 (2012).
Arylenevinylinic and amidic compounds thin films for organic devices
A. Stanculescu, M. Socol, O. Rasoga, M. Enculescu,
in cooperation with
F. Stanculescu, I. Ionita
University of Bucharest, Faculty of Physics, Magurele, Romania
M. Grigoras, L. Vacareanu
“P. Poni” Institute of Macromolecular Chemistry, Iasi, Romania
A.-Maria Albu
University “Politehnica” of Bucharest, Bucharest, Romania
M. Girtan
Laboratoire de Photonique d'Angers, Université d’Angers, Angers, France
In the development of cheap technologies involving organic materials, a special attention was paid to
the search for new organic compounds with adequate properties, determined by their molecular
structure and solid state packing, to replace the expensive inorganic semiconductors in a large area of
applications.
Our research interest was focused on the identification of some π-conjugated systems, containing
functional groups to improve the optical properties and charge carrier transport. We have studied thin
films and heterostructures with active layer of an organic composite, polymer/amidic monomer based
on aniline derivatives (cyan aniline/MM3, dinitro aniline/MM5 [1]) and of oligomers based on aromatic
amines, like triphenylamines (1, 4-bis [4-(N,N’-diphenylamino)phenylvinyl] benzene/L78) and carbazoles
178
(3, 3’-bis (N-hexylcarbazole)vinylbenzene/L13) [2]. The attention was focused on the investigation of the
relationship between morphology and optical and electrical properties, to develop devices with tailored
performances, because the surface morphology plays a determinant role in the properties of the
junctions realized with organic thin films [2].
We have prepared by spin coating thin films of composite material embedding amidic monomers in a
polycarbonate of bisphenol A matrix, and made a spectrophotometric, microscopic and electric
comparative study between these sample and those prepared from the same amidic monomers
deposited by vacuum evaporation. The purpose was to emphasise the effect of the organic matrix on
the optical and electrical properties, in correlation with the morphology and structure of the film [1].
The films obtained from the polycarbonate containing monomers with two nitrous substituents to the
aromatic nucleus (MM5) have shown high transparency and good photoluminescence (PL) in the green
region of the solar spectrum [1].
10-2
a)
10-2
10-3
10-3
10-4
10-4
-5
10-5
-6
10-6
10
Current (A)
Current (A)
10
-7
10
-8
10
MM3
Poly.:MM3
10-9
10-7
10-8
10-9
10-10
10-10
-11
-11
10
10-12
0.1
b)
MM5
poly.:MM5
10
1
Voltage (V)
10
10-12
0.1
1
Voltage (V)
10
Fig. 1: I-V characteristics of different Si/organic/Si structures based on MMx monomer: x=3 (a)
and x=5 (b) [1].
Good electrical transport properties have been evidenced at voltages >0.6 V (I>10-8 A) with a linear I-V
characteristic between 1 V and 10 V [1] (Fig.1).
The composite film prepared with monomer MM3 has shown intense Two Photon Absorption
Fluorescence/TPF, while that prepared with MM5 has shown both Second Harmonic Generation/SHG
and TPF (Fig.2).
179
104
103
300 400 500 600 700
Wavelength (nm)
MM5
Poly.:MM5
Intensity (counts)
Intensity (counts)
MM3
Poly.:MM3
104
103
300 400 500 600 700
Wavelength (nm)
Fig, 2: Non-linear optical effects in MMx and polycarbonate/MMx samples: x=3; 5 [1]
These properties are influenced by the typical morphology and high degree of disorder of the spin
coated layers [1].
Fig. 3: logI-logV characteristics of ITO/L13(L78)/Si(n; p) heterostructures [2].
180
By comparison, most of the heterostructures ITO/oligomer/Si have shown a weak injector contact
behavior both at direct and reverse bias (Fig. 3) and a limitation of the current by the effect of the space
charge [2].
The quadratic dependence between the measured fluorescence and the excitation power for L78 thin
film at laser powers <250 mW has confirmed the two-photon nature of the excitation (Fig. 4). The shape
of the TPF spectra is similar to the shape of the linear fluorescence spectra confirming that both
emissions are generated from the same excited state [2].
Fig. 4: TPF in oligomer thin films. Dependence of TPF intensity on the laser power for L78 thin film [2].
Fig. 5: SEM and AFM images of thin films on different substrates: a) L13 b) L78 [2]
These films embedded some randomly distributed structures (Fig. 5), aggregates with acicular shape
(L78) or platelet shape (L13), developed during the deposition process, but the similar roughness of the
films is correlated with similar scattering, reducing the effect of the surface morphology on the films’
properties [2].
References
181
[1] F. Stanculescu, A. Stanculescu, M. Girtan, M. Socol, O. Rasoga, Synthetic Metals, 161 (23-24), 25892597 (2012)
[2] O. Rasoga, L. Vacareanu, M. Grigoras, M. Enculescu, M. Socol, F. Stanculescu, I. Ionita, A. Stanculescu,
Synthetic Metals 161 (23-24), 2612-2617 (2012)
Hydrothermal synthesis of ZnO-Eu2O3 binary oxide with straight strips
morphology and sensitivity to NO2 gas
A. Stănoiu, C.E. Simion
in cooperation with
S. Somǎcescu1,2, A. Dinescu1, J.M.C. Moreno2
1
National Institute for Research and Development in Microtechnologies, Bucharest-Romania
2
“Ilie Murgulescu” Institute of Physical Chemistry, Romania Academy, Bucharest-Romania
Within the present research, ZnO-Eu2O3 binary oxide have been synthesized using a hydrothermal
route assisted by ionic surfactant (CTAB) highlighting strips like morphology and high sensor signal
towards low NO2 concentration (3ppm) in humid air background. Thus, as obtained powders were the
subjects of several morphological and structural investigations (SEM, XRD XPS) together with an
appropriate evaluation of their gas-sensing properties when exposed to NO2 and CO gases [1].
SEM images reveal a significant quantity of straight strips having a porous nature and prominent
presence of hierarchical structure morphologies (see Fig.1)
Fig. 1 SEM investigations of ZnO-Eu2O3 materials performed after the heat-treatment at 600°C
182
The element relative concentration of Eu obtained from EDAX analysis was 2.7% whereas from
XPS surface analysis it turned to be 3.3%. The obtained X-ray diffraction data was indexed to wurtzite
ZnO (hexagonal with space group P63mc, 186) which corresponds to the JCPDS No. 36-1451. The
exception was the weak feature at 2θ~ 28 deg, indexed to the main peak of Eu2O3 with a body centered
cubic structure (space group Ia3, 206), in agreement with the standard value (JCPDS No. 34-0392).
The XPS analysis was involved in order to determine the chemical states of the elements present
on the surface beside their relative concentrations. Consequently, Figure 2 shows the high resolution
spectra recorded for the Eu 3d transitions before and after the gas sensing investigations.
Fig. 2 The XPS superimposed spectra of ZnO-Eu2O3 materials
The recorded spectra revealed the fact that europium exhibited only the presence of Eu3+ as Eu2O3
on the outermost surface layer (<5nm). This assignment is based mainly on the exhaustive work of
Mercier et al. [2], as well. Another interesting finding was that before and after exposure to toxic gases
(NO2 and CO) the surface chemistry has not suffered changes. Thus, high resolution XPS measurements
revealed a very stable surface of the material which is not affected by successive exposures in different
gaseous environments.
Regarding the gas-sensing investigations, NO2 target gas was mixed with synthetic humid air using
a fully computer controlled system in order to achieve the desired concentration range. The sensitive
materials have been deposited by screen printing over alumina substrates provided with Pt electrodes
on one side and Pt heater on the other side. Samples were exposed to different NO2 concentrations (310 ppm) in humid air background (50% RH). The exposure and recovery time was set to 30 min, while
the stabilization time needed for samples to reach a steady state, was 1h at the beginning of each set of
gas exposure (see Figure 3a).
183
140
(a)
10 ppm NO2
120
Resistance (MΩ)
100
5 ppm NO2
80
3 ppm NO2
60
40
air
50% RH
20
0
S = 26
S = 16
0
1
2
S = 44
3
4
Time (h)
Fig. 3a. Time dependence of the electrical resistance of ZnO-Eu2O3 material during NO2 exposure in
humid air background. The operating temperature was set to 300°C.
The maximum relative humidity of 50% was chosen as an average value for ambient atmosphere.
The measurements were repeated for different operation temperatures in the range between 150300ºC in order to establish the optimum detection conditions.
The gas sensing properties of a n-type polycrystalline metal oxide semiconductor can be properly
evaluated through their sensor signal S [3]. This is defined as the resistance ratio Rgas/Rair when the
sensitive material is exposed to oxidizing gases or Rair/Rgas for reducing gases exposure. Specific to the
tested temperature range, the possible interfering gas is carbon monoxide. Thus, we found out that the
sensor signal towards 500 ppm CO exposure with ZnO-Eu2O3 materials was not higher than 1.09
(arb.units). The work of S. Bai et al. [4] presents a sensor based 1D ZnO nanostructures synthesized by
hydrothermal process using CTAB as organic template. Their material exhibited the highest response to
40 ppm of NO2 together with high selectivity towards CO and CH4 (when tested to the same target gas
concentration). The tests have been done at 400°C as operating temperature. As it can see in Figure 3a,
the detection limit has been decreased until 3 ppm NO2 operated at 300°C. A linear dependence with
respect to the target gas concentrations is shown in Figure 3b.
40
30
2
Signal S=RNO /Rair (a.u.)
(b)
Experimental results
Linear Fit
50
20
10
0
0
2
4
6
8
10
NO2 concentration (ppm)
Fig. 3b. Sensor signal linear-dependence on the NO2 concentration.
Thus, the high sensor signal to NO2 in humid air background beside its low sensitivity towards CO,
recommend ZnO-Eu2O3 as a good candidate in selective detection of NO2.
184
References
[1] S. Somǎcescu, A. Dinescu, A. Stǎnoiu, C.E. Simion, J.M.C. Moreno, Mat. Lett. 2012;89;219-222.
[2] F. Mercier, C. Alliot, I. Bion, N. Thromat, P. Toulhoat, J. Electron Spectrosc. 2006;150;21-26.
[3] N. Bârsan, D. Koziej, U. Weimar, Sens. Actuators B. 2007;121;18-35.
[4] S. Bai, X. Liu, D. Li, S. Chen, R. Luo, A. Chen, Sens. Actuators B. 2011;153;110-116.
Structural, electric and magnetic properties of CoFe1.8RE0.2O4
(RE=Dy, Gd, La) bulk materials
T. Popescu, M. Feder
in cooperation with
G. Dascalu, O. F. Caltun
Faculty of Physics, Alexandru Ioan Cuza University, Iasi, Romania
Modified cobalt ferrites are promising materials for applications like magneto-optical devices and
high-density recording media due to their large coercive field, high magnetocrystalline anisotropy,
moderate saturation magnetization, remarkable chemical stability and mechanical hardness. Pure spinel
cobalt ferrite (CoFe2O4) also exhibits a large magnetostriction coefficient (λs~110 x 10-6), thus making it a
good candidate for sensors and actuators applications.
An increasing attention was recently given to magnetoelectric composites based on cobalt ferrite.
Is is known that substitution / addition of cations in the basic chemical composition of ferrite materials
greatly influence the structural, magnetic, electric and mechanical properties of these compounds. For
example, the effects of manganese and silicon substitutions for iron in cobalt ferrite have been
previously studied and reported [1-3]. Also, the influence of some rare earth (RE) cations, as iron
substituents, on the properties of different types of ferrites was also investigated [4]. The substitution of
iron with lanthanum in the chemical composition of cobalt ferrite determines an increase in resistivity
and a decrease in its dielectric and magnetic losses [5].
185
The present study addresses the effects of RE (RE = Dy, Gd, La) substitution for iron in the spinel
cobalt ferrite CoFe1.8RE0.2O4, on the structural, dielectric, magnetic and magnetostrictive properties of
such bulk materials [6].
For all three types of substitutes, the XRD patterns of the pressed and sintered compacts reveal
the presence of only two phases: a spinel phase and a perovskitic
REFeO3 structure (Fig.1).
Fig.1 XRD patterns for compacts with chemical composition CoFe1.8Gd0.2O4 sintered at 1250 °C, for 5h in
air.
All densities calculated for the substituted samples were lower compared to that obtained for the
stoichiometric cobalt ferrite compact.
The higher porosity of the substituted ferrites may appear as a consequence of the presence of a
relativly high amount of perovskitic phase on the grain boundaries, which may suppress the sintering
process of the pressed compacts, as in case of Ni-Zn ferrite with small RE2O3 substitutions [7].
Regarding the effects of RE substitutions in cobalt ferrite on its magnetic properties, results indicated an
increased coercive field (Hc) and a decreased saturation magnetization (Ms). The reduction of
magnetization was found to be proportional to the ionic radii of the RE substituents, being induced by
the weakening of the magnetic exchange interactions. Enhanced values of Hc for RE doped cobalt
ferrites were expected due to the higher level of spin-orbit coupling compared to CoFe2O4 bulk material.
The variation of magnetoelectric coefficient with the applied dc magnetic field is presented in Fig.2.
Because of the large ionic radii of the RE cation compared to the Fe3+, a distortion of the spinel structure
was induced by the substitution, leading to the development of a spontaneous polarization and an
186
electric response. The magnetoelectric coefficients for CoFe1.8RE0.2O4 are weaker than the ones reported
for Gd and Nd doped nickel ferrite systems [8].
5
CoFe1.8Dy0.2O4
CoFe1.8Gd0.2O4
CoFe1.8La0.2O4
αME (µV/cm Oe)
0
-5
-10
-15
0
1000
2000
3000
H (Oe)
4000
5000
6000
7000
Fig.2 Magnetoelectric coefficient dependence on dc magnetic field.
The magnetostriction curves of the sintered samples are shown in Fig.3. The negative slopes
(dλ/dH) of these curves decrease at low fields due to the increase of coercive fields as the ionic radii of
the rare earth substitutes become larger. Although the maxima of magnetostriction coefficients of
CoFe1.8RE0.2O4 presented decreases of up to 13 %, their values were still higher than those reported for
other ferrites [9].
The studied compacts served as solid targets for pulsed laser deposition of high magnetostriction
coefficient thin films [10].
187
Parallel
CoFe2O4
CoFe1.8Dy0.2O4
CoFe1.8Gd0.2O4
CoFe1.8La0.2O4
Deformation (ppm)
0
-50
-100
-150
-200
-10000 -8000 -6000 -4000 -2000
0
2000 4000 6000 8000 10000
H (Oe)
Fig.3 Magnetostriction curves for all sintered cobalt ferrite samples.
References
[1] O.Caltun, I.Dumitru, M.Feder, L.Diamandescu, I.Bibicu, F.Vasiliu, N.Lupu, V.Vilceanu, J. Optoelectron.
Adv. Mater. 10 (2008) 1775-1778.
[2] O.Caltun, I.Dumitru, M.Feder, N.Lupu, H.Chiriac, J. Magn. Magn. Mater. 320 (2008) e869-e873.
[3] M.N.Palamaru, A.R.Iordan, C.D.Aruxandrei, I.A.Gorodea, E.A.Perianu, I.Dumitru, M.Feder, O.F.Caltun,
J.Optoelectron. Adv. Mater. 10 (2008) 1853-1856.
[4] M.A.Ahmed, N.Okasha, M.M.El-Sayed, Ceram. Inter. 33 (2007) 49-58.
[5] P.Kumar, S.K.Sharma, M.Knobel, M.Singh, J.Alloy. Compd. 508 (2010) 115-118.
[6] G.Dascalu, T.Popescu, M.Feder, O.Caltun, J. Magn. Magn. Mater. 333 (2013) 69-74.
[7] N.Rezlescu, E.Rezlescu, Journal de Physique IV 7 (1997) C1-225-C1-2.
[8] K.Kamala Bharathi, J.Arout Chelvane, G.Markandeyulu J. Magn. Magn. Mater. 321 (2009) 3677-3680.
[9] V.L.Mathe, A.D.Sheikh, Physica B 405 (2010) 3594-3598.
[10] G. Dascalu, D. Durneata, O.F. Caltun, IEEE Trans. Mag. 49 (2013) 46-49.
188
PATENTS AND PATENT
REQUESTS
189
PATENTS
C.M. Teodorescu, N. Gligan, M.L. Gligan
Nanocluster source for the selection depending on cluster size
a 2006 00716 A2 (RO-BOPI 4/2009 G08G p. 42)
M. Popescu, F. Sava, A. Lőrinczi, A. Tomescu, C. Simion, G. Socol, I.N. Mihailescu, S. Miclos,
D. Savastru
Material sensitive to methane gas and threshold sensor for methane detection
Brevet OSIM Nr. 123461 /29.06.2012
PATENT REQUESTS
R. Dragomir
Digitization method of instruments belonging to guitar family with metallic chords by building
of conducting bands matrix
A/00600/ 16.08.2012
R. Dragomir
Digitization method of instruments belonging to guitar family with metallic chords by means of
identification circuits of maximum potential key and threshold potential setting
A/00599/ 16.08.2012
C. Cotirlan-Simioniuc
Sensor with nanostructured surface for resonannt techniques of single molecule detection
A/00343 / 16.05.2012
C. Cotirlan-Simioniuc, M.F. Lazarescu
Method and measuring device of optical properties of thin films deposited on surfaces or
interfaces with internal total reflexion
A/00501/ 24.05.2011
C. M. Teodorescu, N.G. Apostol
Fabrication of targets with nanometric thickness for interactions with power lasers based on
metal evaporation on solidified rare gases
A/00899 / 29.11.2012
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SEMINARIES
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SEMINARIES
Regular Seminaries
General Seminar, 20 March 2012, 10:00
"La microscopie électronique en transmission en mode balayage : un outil indispensable pour
l’étude des nanostructures" presented by Dr. Jacques Werckmann, Visiting Professor at Federal
University of Rio de Janeiro (UFRJ), Brazil
General Seminar 24 April 2012, 10:00 Superconducting research at Beijing University of
Technology (24.04.2012). Prof. Hong Li Suo (Beijing University of Technology-Beijing China)
General Seminar - Agilrom Scientific SRL Romania,Thursday 21 May 2012, 10:00 hours. Title:
"The right technique in elemental inorganic analysis: AAS, AES or ICPMS" Dr. Hans-Dieter
Projahn, Product Specialist AA & MP-AES ,Spectroscopy Solutions Division, Agilent
Technologies, Germany si Dr. Alin Mogos, Spectroscopy Department, Agilrom Scientific SRL,
Romania
General Seminar, Wednesday 23 May 2012, 11:30 hours
"Reversible electrical switching of spin polarization in multiferroic tunnel junctions" presented
by Dr. Marin Alexe, MPI Halle, Germany
General Seminar - AMS 2000 Trading Impex SRL, Vineri 27 Iulie 2012. Titlu: "Noi tehnici de
lucru XRD si aplicatiile lor in caracterizarea materialelor" prezentat de Dl. Uwe Preckwinkel,
reprezentantul Rigaku Corporation pentru Europa de Est
Workshops
Advanced workshop on solar energy conversion
21-23 May 2012, Bucharest, Romania
21.05.2012
Eric Daniel GLOVACKI, Linz Institute for Organic Solar Cells (LIOSJohannes Kepler
University, Linz, Austria
Learning from nature: hydrogen-bonded macromolecules for organic electronics
Paolo FORNASIERO: University of Trieste, Italy
Photocatalitic H_2 and added value byproducts: the role of metal oxide systems in their
synthesis from liquid oxygenates
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Vanni LUGHI: University of Trieste, Italy
Nanotechnology for photovoltaics
Leonid CULIUC: Institutul de Fizica Aplicata al ASM, Chisinau, R. Moldova
Preparation of solar cells by low cost spraying technology
22.05.2012
Paolo FORNASIERO: University of Trieste, Italy
Exceptional activity for methane oxidation with catalysts prepared by modular assembly of
[email protected] subunits
Stefano FABRIS: Scuola Internazionale Superiore di Studi Avanzati, Trieste, Italy
Computational modeling of new materials for solar-driven fuel production
Nicola SERIANI: ICTP Trieste, Italy
Computational materials science for energy applications
Teketel Yohannes ANSHEBO: Addis Ababa University , Ethiopia
Conducting polymers based photo-electrochemical solar energy conversion
Branko PIVAC: Rudjer Boskovic Institute, Zagreb, Croatia
Nanomaterials for photovoltaics
Mihaela GIRTAN: Angers University, France
Electronics and photonics: two sciences in the benefit of solar energy conversion
23.05.2012
Daniel EGBE: JKU Linz Institute for Organic Solar Cells (LIOS) / Institute of Physical
Chemistry, Linz, Austria
Polymer-based organic solar cells
Serdar SARICIFTCI: JKU Linz Institute for Organic Solar Cells (LIOS) / Institute of Physical
Chemistry, Linz, Austria
Organic-inorganic nanostructures for solar energy conversion
Serdar SARICIFTCI: JKU Linz Institute for Organic Solar Cells (LIOS) / Institute of Physical
Chemistry, Linz, Austria
Charge carrier transport in organic photovoltaic devices
Daniel EGBE: JKU Linz Institute for Organic Solar Cells (LIOS) / Institute of Physical
Chemistry, Linz, Austria
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ANSOLE - solar energy for Africa
The 7th International Conference on
Advanced Materials,
Rocam 2012
28-31 August 2012, Brasov, Romania
Section Organizers
S4: Thin Films of Multifunctional Materials for Advanced Applications
Joe Greene, University of Illinois at Urbana-Champaign, USA
Lucian Pintilie, National Institute of Materials Physics, Romania
Maria Dinescu, National Institute for Laser, Plasma and Radiation Physics, Romania
Nicu-Doinel Scarisoreanu, National Institute for Laser, Plasma and Radiation Physics, Romania
S5: Advanced Ceramics: From Micro- to Nanoscale
Matjaz Valant, University of Nova Gorica , Slovenia
Magda Nistor, National Institute for Laser, Plasma and Radiation Physics, Romania
Liviu Nedelcu, National Institute of Materials Physics, Romania
S7: Modelling and Characterization of Advanced Materials
Daniel Vizman, West University of Timisoara, Romania
Marius Volmer, Transilvania University of Brasov, Romania
Ovidiu Florin Caltun, "Alexandru Ioan Cuza" University of Iasi, Romania
Corneliu Ghica, National Institute of Materials Physics, Romania
Foreign participants
Dr. Gwenel Le Rhun
RF Components Laboratory, CEA-LETI-MINATEC, Grenoble, France
Dr. Leo McGilly
Ceramics Laboratory, EPFL, Lausanne, Switzerland.
Prof. Marina Tjunina
University of Oulu Microelectronics and Materials Physics Laboratories Faculty of Technology
University of Oulu, Oulu, Finland
Dr. Pietro Delugas
Dipartimento di Fisica, Università degli Studi di Cagliari, Monserrato (CA), Italy
Dr. Florencio Sanchez
ICMAB-CSIC, Bellaterra, Spain
Dr. Andreas Klein
University of Darmstadt, FG Oberflächenforschung, Darmstadt, Germany
Dr. Nick Barrett
CEA Saclay, CEA DSM, IRAMIS, Gif Sur Yvette, France
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Diaspora în Cercetarea Stiintifica si Invatamantul Superior din Romania „Seminte de
Viitor – Seeds for the Future”, 25-28 Septembrie 2012, Bucuresti.
1. Workshop "Teorie si experiment in fizica suprafetelor, interfetelor si
nanoparticulelor", 26 - 27 September 2012.
2. Workshop "Materiale in conditii extreme: procesare, caracterizare si
aplicatii", 26 - 27 September 2012.
Workshop "Teorie si experiment in fizica suprafetelor, interfetelor si nanoparticulelor"
Lectii invitate diaspora
Adrian Ionescu (Cavendish Laboratory, UK)- Suprafete si interfete formate de straturi subtiri si
de nanoparticule fero- si antiferomagnetice.
Andrei Manolescu (School of Science and Engineering, Reykjavik University, Iceland)-Stari
electronice in nanowires cilindrice
Didina Serban (CEA Saclay, France)-Metode exacte pentru sisteme magnetice unidimensionale
Marin Alexe (Max Planck Institute of Microstructure Physics, Halle/Saale, Germany) - Domenii
si interfete in materiale feroice
Lucian Filip (Advanced Technology Institute, University of Surrey, Guildford, United
Kingdom) - Efecte de tunelare in capacitori n-4H-SiC/SiO2 la temperaturi scazute
Workshop “Materiale in conditii extreme: procesare, caracterizare si aplicatii”
Lectii invitate diaspora
A. Jianu
Karlsruhe Institute for Technology, Karlsruhe, Germany
T. Retegan
Chalmers University, Gothenburg, Suedia
D. Axinte
University of Nottingham, UK
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M. Tomut
GSI Darmstadt, Germany
L. Zigoneanu
Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina
27708, USA
M. Calin
Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research,
Dresden, Germany
J. Groza
Univ. California Davis, USA
EVENTS
Advanced workshop on solar energy conversion, 21-23 May 2012, Bucharest, Romania
Renewable energy resources are needed to meet our clean energy demand. Since any long term
energy supply must be based on solar energy, photovoltaic energy conversion will become
indispensable in the future.
The transition from the conventional energy, based on fossil fuels or nuclear fission, to
sustainable energies, is presently hampered by the low efficiencies or high costs of the available
materials. The development of new materials by engineering their structure at the nano-scale is
recognized to be the key issue which could increase the performance of both renewable energy
conversion and energy storage. In this sense, new materials are a of crucial importance for a
possible transition towards a more sustainable energy economy.
The Workshop has included of invited lectures addressed by leading researchers in the field, as
well as contributed oral presentations. Also, a poster session will be organized.
The main topics covered in this workshop were:
•
•
•
•
photovoltaics
artificial photosynthesis
electrocatalysis
batteries
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The workshop is organized by: the UNESCO Chair on Sustainable Development at Horia
Hulubei Foundation (Magurele-Bucharest); the National Institute for Materials Science
(Magurele-Bucharest); Faculty of Physics, University of Bucharest; Abdus Salam International
Centre of Theoretical Physics (Trieste) and the National Institute of Physics and Nuclear
Engineering (Magurele-Bucharest).
Scientific directors: Teketel Yohannes Anshebo (Addis Ababa), Stefan Antohe (Bucharest),
Ionut Enculescu (Bucharest), Joseph Niemela (ICTP)
Scientific secretary: Victor Barsan (Bucharest)
Local organizers : Sorina Iftimie, Adrian Radu, Alin Velea (Bucharest)
We mention among the participants:Eric Daniel Glovacki, Linz Institute for Organic Solar
Cells (LIOSJohannes Kepler University, Linz, Austria, Paolo Fornasiero , University of
Trieste, Italy, Vanni Lughi , University of Trieste, Italy, Leonid Culiuc , Institutul de
Fizica Aplicata al ASM, Chisinau, R. Moldova, Stefano Fabris , Scuola Internazionale
Superiore di Studi Avanzati, Trieste, Italy, Nicola Seriani , ICTP Trieste, Italy, Teketel
Yohannes Anshebo , Addis Ababa University , Ethiopia , Branko Pivac , Rudjer Boskovic
Institute, Zagreb, Croatia, Mihaela Girtan , Angers University, France, Daniel Egbe , JKU
Linz Institute for Organic Solar Cells (LIOS) / Institute of Physical Chemistry, Linz,
Austria, Serdar Sariciftci , JKU Linz Institute for Organic Solar Cells (LIOS) / Institute of
Physical Chemistry, Linz, Austria .
The 7th International Conference on Advanced Materials, ROCAM 2012, August28-31,
Brasov, Romania
During the conference have been presented 274 contributions by researchers coming from
Algeria, Belgium, Bulgaria, Brazil, China, France, Germany, Greece, Hungary, India, Ireland,
Iran, Israel, Italy, Japan, Moldavia, Montenegro, Poland, Romania, Russia, Serbia, Slovenia,
Slovakia, South Korea, Spain, Sweden, Thailand, Tunisia, Turkey, UK, Ukraine, USA.
This conference has benefited from the participation of personalities of high prestige in the field
such as: Prof. Roberto FORNARI (Germany), director of IKZ Berlin, associate professor at the
University Humbold Berlin, president of the “International Organization for Crystal Growth”; 3
Editor-in-Chief [Prof. Thomas KUECH-USA (J Crystal Growth), Prof. Joseph GREENEUSA (Thin Solid Films) and Prof. Martin GREEN-Australia (Progress in Photovoltaics:
Research and Applications-Impact Factor: 5.789)]; Prof.Tatau NISHINAGA (Japan), expresident of “International Organization for Crystal Growth”; Sefik SUZER (Turkey),
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editorApplied Surface Science; Jeffrey DERBY (USA), ex-president of the American Society
on Crystal Growth.
* Dr. Liviu Nedelcu, organizer of Session S5: Advanced Ceramics: From Micro- to Nanoscale,
to International Conference on Advanced Materials-ROCAM 2012, August 28-31, Brasov,
Romania (2012)
* Dr. Pintilie Lucian, organizer of Session S4: Thin Films of Multifunctional Materials for
Advanced Applications, to International Conference on Advanced Materials-ROCAM 2012,
August 28-31, Brasov, Romania (2012)
Exploratory workshop “Thin films of multifunctional materials”, Brasov, 28-30.08.2012. Invited
speakers:
Dr. Gwenel Le Rhun
RF Components Laboratory, CEA-LETI-MINATEC, Grenoble, France
Dr. Leo McGilly
Ceramics Laboratory, EPFL, Lausanne, Switzerland.
Prof. Marina Tjunina
University of Oulu Microelectronics and Materials Physics Laboratories Faculty of Technology
University of Oulu, Oulu, Finland
Dr. Pietro Delugas
Dipartimento di Fisica, Università degli Studi di Cagliari, Monserrato (CA), ITALY
Dr. Florencio Sanchez
ICMAB-CSIC, Bellaterra, Spain
Dr. Andreas Klein
University of Darmstadt, FG Oberflächenforschung, Material- und Geowissenschaften
Materialwissenschaft, Darmstadt, Germany
Dr. Nick Barrett
CEA Saclay, Gif Sur Yvette, France
Research Director IRAMIS SPCSI CEA-Saclay
Diaspora în Cercetarea Stiintifica si Invatamantul Superior din Romania „Seminte de
Viitor – Seeds for the Future”, 25-28 Septembrie 2012, Bucuresti.
I.Workshop "Theory and experiment in surface, interface and nanoparticle physics"
September 26-27, 2012 (Chair: Dr. Cristian Mihail Teodorescu)
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Intensive studies of surfaces interfaces and nanoparticles reached an unpreceded intensity during
the last three decades, resulting - for instance - in several Nobel prizes (Physics: 1981, 1985,
1986, 1987, 1989, 1991, 1998, 2000, 2005, 2007, 2009, 2010; Chemistry: 1983, 1986, 1987,
1989, 1992, 1996, 1998, 1999, 2000, 2001, 2003, 2007, 2010, 2011). The overwhelming
majority of phenomena connected to the interaction (chemical, mechanical, metallurgical,
electromagnetic) between two bodies takes place at the interface between the two bodies. Also,
the physical and chemical properties of surfaces govern the reactivity, degradation, corrosion,
catalysis, wear, reflectrivity and absorption of electromagnetic radiation. The science of
nanoparticles, which are entities presenting a high ratio between atoms or molecules situated at
the surface and those from the bulk finds nowadays more an more applications in information
storae technology, various kinds of sensors, catalysis, molecular identification ("electronic
nose"), medical applications (targeted drug delivery, hyperthermia, biosensors), remarkable
optical properties. Nanoparticles are nowadays the base building blocks of nanostructured
materials, metamaterials, photonic crystals, materials with miscellaneous applications (from civil
engineering to textile industry or to paints, varnishes, coatings, etc.)
The more and more diversified paradygms in surface, interface and nanoparticle science cover
nowadays different areas belonging to fundamental physics, applied physics, chemistry,
metallurgy and materials science, biochemistry, biology; also, a multitude of ab-initio theories,
phenomenologies and mathematical physics concentrate efforts in this area. Given the diversity
of these approaches, very often the communication between these distinct areas is difficult. In the
organization of this workshop, we will use an important characteristic of Romanian or
Romanian-born scientists: the ability of understanding at an acceptable level both the
experimental, applied aspects and the theoretical, fundamental aspects, especially in different
areas of Physics. More concretely, probably owing to the Romanian school which aimed in the
past the simultaneous formation of scientists as theoreticians or experimentalists, Romanian
experimental scientists are not completely isolated from theoretical methods or models, and
theoreticians are connected also to the experimental methods used to probe their theories.
The workshop had 38 participants, 20 from Romania and 18 scientists working abroad.
About one half (i.e. 7) of the contributions presented to this workshop had this mixed character,
theoretical and experimental. There were also some (i.e. 2) purely theoretical contributions, and
there were also some contributions which belonged to the experimental science only (6). The aim
of this workshop was to create a synergy between theoreticians and experimentalists, such that
theoreticians may be initiated in the most recent experimental techniques used to date, and
experimentalists to be made aware of the most advanced theoretical predictions susceptible to be
confirmed experimentally and put into practice for practical applications. Such theoretical and
experimental workshops are, unfortunately, not that numerous in contemporary science; under
the auspices of the common national interest of increase of the visibility of Romanian scientists
worldwide, it is to suppose that a net benefit will result for contemporary science, i.e. to identify
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3-5 subjects of extreme fertility on which both theoreticians and experimentalists can
collaborate; at the same time, one has to identify commn subjects of interests for scientists
working in Romania and abroad.
Wednesday, September 26
1.The first talk was given by Mrs. Nicoleta Apostol, PhD student from the Surfaces and
Interfaces Group of the National Institute of Materials Physics (NIMP), which presented the talk
"Reactivity and magnetism in ferromagnetic thin layers grown on semiconductors by molecular
beam epitaxy"
This work represents about 75 % of her PhD thesis and analyzes the following systems:
-clean Si(001), where Nicoleta's team demonstrated that Si(001), when atomically clean,
presents surface reconstructions such as (4 x 2) and (6 x 2). The usual (2 x 1) reconstruction,
which was believed until now to be a certain signature of clean Si(001), occurs also in the case of
a contamination of half a monolayer of CO. These CO radicals are attached to surface Si dimers
and this gives the superstructure (2 x 1). Also, it is shown that surface analysis by Auger electron
spectroscopy and by LEED induces a much stronger surface contamination than the analysis by
XPS.
-Fe/Si(001), where it was shown that ferromagnetism exusts, one computes the atomic
magnetic moment of Fe (1 Bohr magneton) and one establishes that the interface layer obtained
by high temperature deposition is formed by Fe3Si.
-Sm/Si(001), where one shows that this system is also ferromagnetic. In addition to
Fe/Si(001), this system exhibits also long range order. The ferromagnetic compound formed at
the interface is Sm4Si3, co-existing with SmSi2, non-ferromagnetic. Also, the Nicoleta and her
co-authors demonstrated that the interpretation of Sm 3d XPS spectra published to date are
wrong and explained which was the error of these interpretations.
-Mn/Ge(001) deposited at high temperature (above 250 °C) forms a room temperature
ferromagnetic alloy , which is a mixture between diamond-like Fe with Mn substituted (each Mn
atom having 4 Ge neighbors) and a CsCl-tye crystal structure, where each Mn has 8 Ge
neighbors.
-Fe/Ge(001) deposited at elevated temperatures (700 °C) formes a diluted ferromagnetic
semiconductor. The long-range crystalline order of Ge(001) is kept, there is room temperature
ferromagnetism, and also a string uniaxial magnetic anisotropy.
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The results were published in J. Mater. Sci. (x 2), Phys. Stat. Solidi, Appl. Surf. Sci.; some
results presented here are not yet published.
2. Dr. Adrian Ionescu - "Surfaces and interfaces formed by thin layers and nanoparticles
exhibiting ferromagnetism and antiferromagnetism"
Dr. Adrian Ionescu is currently Director of the Materials Growth Facility, Thin Film Magnetism
Group, Cavendish Laboratory, University of Cambridge, UK
In this talk he presented new experiments on nanoparticles and nanostructured systems in
magnetic layers used as biosensors, and also in Eu oxide based nanostructures. During the
discussions, it was asserted that Dr. Ionescu will certainly benefit fully from the expertise of the
surface science team in NIMP connected both to electron spectroscopies of rare earth oxides, and
also feom the spin- and angle-resolved photoemission facility.
3. Dr. Nicoleta Lupu - " Effect of the surface coordination chemistry on the magnetic/electric
properties of 1-D and 2-D nanostructures "
Dr. Nicoleta Lupu is actually General Manager of the National Institute for Technical Physics
Iasi
Surface chemistry is of great importance for the macroscopic behavior of magnetic
nanomaterials. On the other hand, for 2-D and 3-D materials, the magnetic behavior of surface
region atoms plays an important role in determining the macroscopic magnetic properties of the
whole system. The symmetry is reduced for the chemical surroundings of the magnetic metal
cations at the surface due to the incomplete coordination sphere, which leads to local disordered
spin structures.
In this report one discussed recent results on the effect of ligands on the surface chemistry,
magnetic and magnetostransport properties of: (1) Fe/Fe2O3 and Fe/Fe3O4 core-shell
nanoparticles and (2) e-beam evaporated Co and Ni81Fe19 thin films with thicknesses below
300 nm.
Core-shell nanoparticles have been prepared by high-energy ball milling. In the presence of air
or Ar, the Fe core was progressively covered with a Fe2O3 shell, and the obtained Fe/Fe2O3
nanoparticles are ferromagnetic, whilst the Fe/Fe3O4 core-shell nanoparticles obtained by wet
milling of Fe microparticles exhibit a weak ferromagnetic behavior. To understand the surface
chemistry and its influence on the magnetic properties of Fe/FexOy core-shell nanoparticles, their
surface was systematically modified with ligands. The change of the magnetic properties of
nanoparticles correlates with the specific coordinating functional group bound on the
nanoparticles surface, suggesting the decrease in spin-orbital coupling and surface anisotropy of
magnetic nanoparticles due to the changes in the surface coordination. The main advantage of
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such core-shell nanoparticles in biomedical applications, compared with simple Fe-oxides
nanoparticles, resides in their easier use and manipulation for specific applications.
The induced surface spins disorder in Ni81Fe19 thin films with bulk in-plane anisotropy is less
significant when the ligands are used for a short period of time, whereas long-time functionalized
thin films clearly show an induced out-of-plane surface anisotropy competing with the in-plane
bulk one, and determining the increase of the coercive and saturation fields. Co functionalized
thin films develops some random local surface anisotropies which in combination with the bulk
out-of-plane anisotropy reduce the coercive and saturation fields. The easy axis of Co thin films
is tilted from out-of-plane towards in-plane direction when the Co-Co metallic bonds from the
surface are destroyed by ligand.
4. Dr. Cristian M. Teodorescu - "Surface reactivity, charge transfer and energetic band
bendings at metal-ferroelectric contacts"
Dr. Cristian M. Teodorescu is the leader of the Surfaces, Interfaces and Electron Spectroscopies
group from the National Institute of Materials Physics Bucharest-Magurele
This communication presented last minute results on the growth of gold layers on PZT
[Pb(Zr0.2Ti0.8)O3] deposited on STO [SrTiO3], investigated in-situ by X-ray photoelectron
spectroscopy, with gold thicknesses in the range 0.2-10 nm. Prior to the Au growth, the samples
are characterized by Piezoresponse Force Microscopy in order to assess the relative weight of
ferroelectrically poled domains. By X-ray photoelectron spectroscopy one identifies two phases,
whose compositions are quite close to nominal PZT. The first phase is manifested by all of its
binding energies (Pb 4f, Ti 2p, Zr 3d, O 1s) sensibly equal to the tabulated values for PZT (in the
NIST XPS database), whereas the second phase exhibits all core levels shifted by ~ 1 eV towards
higher binding energies. By taking into account also scanning probe microscopy images together
with recent photoemission results from the literature, the second phase is ascribed to P(+)
(polarization pointing upwards, from PZT to vacuum) regions of PZT, whereas the first phase is
attributed to regions with no net ferroelectric polarization. Gold deposition induces a band
bending of PZT - Au ~ 0.4-0.5 eV, rigidy for both phases; this manifests as similar shifts for all
core levels towards higher binding energies when gold is deposited. The gold 4f core level
exhibits also a unusually low binding energy component 1 eV below the metal-like Au 4f
binding energy position (83.8 eV). This implies the existence of negatively charged gold, or of a
quite unusual phenomenon, electron transfer from PZT to Au. This is highly improbable, since
from the band bending behaviour it is inferred that the unpoled PZT phase should have a higher
work function (it is p-doped). Most probably this charge transfer occurs towards Au
nanoparticles, which have even higher ionization energies than p-doped PZT. High resolution
transmission electron microscopy evidenced the formation of such isolated nanoparticles.
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Also, the last part of the talk has a theoretical character, it was proven how one can determine the
shape of the band bending occuring both at metal / unpolarized semiconductor and at a metal /
polarized ferroelectric.
5. Prof. Andrei Manolescu - "Electronic states in cylindrical nanowires"
Prof. Andrei Manolescu is employed actually at the Universitaty of Reykjavik (Iceland). He is
a renowned scientist, having during the last five years several publications in Nature (one)
Science (one) and Nature Genetics (six papers).
The thematic outlined in this talk concerns the quantum treatment of some systems of growing
interest in applied research: that of electrical transport through nanowires, including transport of
spin-polarized charge carriers. As particular cases, systems were analyzed which present
spontaneous symmetry breaking in electroni properties, Kondo systems, supersconducting
systems with quenching of the magnetic field, effects of Rashba-Dresselhaus spin-orbit
interaction, etc.
6. Dr. Didina Serban - "Exact methods for magnetic one-dimensional systems"
Dr. Didina Serban leads the group of Mathematical Physics at the Institute for Theoretical
Physics of the Commissariat a l'Energie Atomique, Saclay, France.
In the presentation of the exact methods one noticed a considerable effort of the mathematical
theoreticians on the levels of the experimentalists. In brief, the aim of this research is to establish
equivalencies between methods which use completely different formalisms, such that between
superstring theory with conformal field theory, or between some mathematical generalized
models with second quantization (or field theory) models. The interest of such an activity is
primordial, since one knows that among the most critical problems of modern physics is
connected to the perturbative approach of the wide majority of systems describing real situations,
bith in quantum mechanics and field theory formalisms. It is straightforward that a wide class of
cases exists where the interaction constant is considerably larger than unity, therefore the
successive perturbation orders give increasing contributions, instead of having the intensity of a
contribution decreasing with the order of the perturbation. The nonperturbative field theories are,
as a consequence, of large actuality. The talk of Dr. Didina Serban presented for non-initiated an
overview of this extremely fascinating area.
7. Dr. Marian Alexe - "Domains and interfaces in ferroic materials"
Dr. Marian Alexe is Senior Scientist at Max Planck Institute for Microstructure Physics,
Halle. Probably one should mention that Dr. Marin Alexe publishes quite often in Nature
Materials or in Advanced Materials and his Hirsch index is about 40.
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Functional perovskite materials gain increasing significance due to their wide spectrum of
attractive properties, including ferroelectric, ferromagnetic, conducting, superconducting, and
multiferroic. Due to the developments of recent years, materials of this type can conveniently be
grown in the form of epitaxial films, multilayers, superlattices, and well-ordered arrays of
nanoislands, opening new avenues in addressing new phenomena which do not exist in single
phase materials.
The present talk will address topics which have been recently under focus, including topological
vortices and vertices in ferroelectrics and multiferroics, anomalous photovoltaic effect and
tunnel effects in multiferroic junctions, and which are closely related to domain walls and
interfaces. A considerable attention will be given to the structure and functional properties of
domain walls in multiferroic materials.
Quite important results were evidenced regarding the structure of ferroelectric domanis. Dr.
Alexe has shown, for instance, that charged adjacent walls (such as →←) extend over 4-5
elementary cells, while uncharged domain walls (on the type ↑↓) have practically zero width.
During the discussions, there was the statement that still some ambiguities exist concerning the
surfaces of the ferroelectrics, and that their behaviour may be evidenced by photoelectron
spectroscopical techniques.
8. Mr. Leontin Padurariu - "Non-linear effects generated at crystallite borders in
ferroelectrics"
Although he is only in his first year oh PhD work, Mr. Leontin Padurariu from the Alexandru
Ioan Cuza University Iasi preseted a very nice talk, in which he presented theoretical models
and simulations on ferroelectric materials. The non-linear dielectric properties promote
ferroelectric materials as principal active or passive elements to be used in microelectronics. For
being suitable in non-linear applications a material must fulfill the following characteristis: low
permittivity (some hundreds), a string variation of the permittivity with the applied field and low
losses. Unfortunately, the known ferroelectric materials are characterized by a large permittivity
and a high tunability. Therefore, it is of interest to find materials with non-linear properties, but
with low dielectric constant.
In order to reduce the permittivity one strategy was to reduce the grain size of a ferroelectric
ceramics at nanoscale level. For instance, for a fine ceramic of BaTiO3 with a grain size below
100 nm the permittivity decreases to values lower than 1000, whereas the dependence of the
permittivity on the electric field gets linearized. A ceramic mat be considered as a composite
with ferroelectric grains (with the permittivity dependent on the local field) and ferroelectric
borders (with a low permittivity, constant as function on the electric field). In order to compute
the local electroc fields for different virtual ceramics with different grain sizes, one uses the
Finite Element Method; following this computation, the macroscopic electrical properties of the
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system are readily obtained (effective permittivity, tunability). Hence, one obtains similar results
with the experiment: the decrease of the effective permittivity (εef) and the linearization of
thedependence εef(E).
The Finite Element Method was applied also for the description of other kind of composites:
dielectric/ferroelectric composite with random phase distribution, composite with ferroelectric
inclusions in a dielectric matrix and composite with dielectric inclusions in a ferroelectric matrix.
The best properties were obtained for composited with dielectric inclusions in a ferroelectric
matrix: low permittivity and high tunability. These properties were observed both experimentally
and theoretically in porous ferroelectric materials.
Thursday, September 27
9. Prof. Nicolae Barsan - "Experimental studies on the reactivity of gases with nanoparticles of
metal oxides"
Prof. Nicolae Barsan is a tenured scientist at the Universitaty of Tübingen, being well-known in
the community of gas sensors and having, also, a Hirsch index of nearly 40.
Professor's Barsan talk was concentrated on actual studies on the influence of the transport
properties of nanoparticle systems of metal oxides by the gas adsorption. The talk treated
fundamental problems, but also strongly oriented towards applications, by assessing the
sensitivity of the devices manufactured based on these nanostructured systems for different
gases. A quite important aspect relies on the influence of the humidity (water vapor pressure) on
the sensor characteristics, and also on the reversibility of the adsorption / desorption processes.
Also, in the talk some results were presented for thefirst time concerning the realization of gas
sensors on plastic substrates.
10. Prof. Simion Astilean - " Plasmonic nanoparticles with biomedical applications "
Prof. Simion Astilean is group leader at the Babes-Bolyai University, Institute for
Interdisciplinary Research in Bio-Nano-Sciences and Faculty of Physics, Cluj-Napoca, Romania
Currently, there is an increasing interest for using plasmonic nanoparticles in various biomedical
applications like sensing, imaging, diagnostic and therapy. In this talk we present our recent
results in fabrication of large variety of plasmonic nanostructures and some of their applications
in molecular spectroscopy, cell imaging and localized hyperthermia [1-5]. The first route of
fabrication involves the use of self-assembled polystyrene nanospheres as lithographic masks to
deposit metal and generate periodic arrays of nanoparticles or nanoholes. The second route
involves chemical synthesis of gold and silver nanoparticles, mainly of anisotropic shape (rods,
prisms, stars-shaped), in presence of various biopolymers (chitosan, poly(ethylene) glycol,
pluronic, gelatine) which are interesting due to their good biocompatibility and controllable
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plasmon resonances from visible to the biological transparent near-infrared (NIR) window. We
present gold and silver nanoparticles able to operate as multi-modal spectroscopic enhancers in
SERS and metal-enhanced fluorescence (MEF) as well as effective antimicrobial or
hyperthermia agents. For instance chitosan-coated silver nanoparticles of triangular shape have
been successfully implemented for sensing via surface plasmon resonance (LSPR) and surfaceenhanced Raman scattering (SERS) both in solution and on solid substrate. In a separate study
we have assessed the potential of chitosan-coated silver nanoparticles of triangular shape to
induce photothermal destruction of cancer cells by hyperthermia under NIR laser irradiation.
Such hybrid nanoparticles can act synergistically against strains of bacteria while the
biochemical changes induced in the bacterial cell wall can be monitored via SERS.
The as fabricated plasmonic substrates complemented with good biocompatibility and chemical
stability can hold a significant potential for implementing novel biomedical sensing and imaging
methods.
11.Dr. Ovidiu Pana - "Magnetic nanoparticles with applications in magnetic hyperthermia"
Dr. Ovidiu Pana is Department Head at the National Institute for Isotopic and Molecular
Technologies Cluj-Napoca
Dr. Pana's talk was a continuation from a more physical approach of Prof. Astilean's talk. Dr.
Pana presented experimental and theoretical results obtained on core-shell nanoparticles
functionalized with polymers. A new, interesting, phenomenon was evidenced and explained for
LSMO nanoparticles La,Sr)MnO3, relying on the charge transfer from polymer's
 orbitals
towards the magnetic nanoparticle. This supplementary charge is localized in defects on the
oxygen vacancy type and re-strenghten the intensity of the indirect exchange (or superexchange)
coupling between Mn3+ and Mn4+ ions separated by such an oxygen vacancy. The efect is
interesting, since it is reproducibe and have a tremendous applicative potential, offering the
possibility to control the magnetic properties via the charge transfer at the surface. One may
easily imagine cellular pH sensors, or selective hyperthermic apoptosis of some kinds of cells
only. It is true that in presenting such applications we don't speak yet about microelectronics,
mecatronics or robotics, but for all applications foreseen one has also to consider interactions of
physical systems with tailored properties with the biological matter.
12.Dr. Catalin Miron - "Probing structure and chemical reactivity of unsupported
nanoparticles using soft X-ray spectroscopie "
Dr. Catalin Miron is Principal Beamline Scientist on one of the most demanded synchrotron
radiation facilities in Europe: the beamline Pleiades of the synchrotron Soleil Saint Aubin,
France
206
Novel experimental investigations have been recently reported to explore the interaction between
mechanisms between isolated nano-objects and radiation.
In order to perform such studies, in the PLEIADES group at the SOLEIL synchrotron radiation
laboratory (France), we developed a multipurpose source chamber (MPSC), allowing to generate
in vacuum a focused beam of isolated nanoparticles sprayed using a conventional aerosol
generation technique. The synchrotron radiation crosses the nanoparticle beam at right angle at
the focal point of a home made aerodynamic lens. In the interaction region, the particle beam
diameter and the local particle density are estimated to be 300 µm and 107 cm-3, respectively.
These conditions allow us to perform X-ray absorption spectroscopy (XAS), X-ray Photoelectron
Spectroscopy (XPS) or Auger spectroscopy of isolated, size-selected nanoparticles. In addition to
the description of the experimental method, two examples will be given.
The first one concerns the measurement of electron angular distributions from isolated silica
nanoparticles with sizes between 44 and 185 nm, using an original Double Toroidal Analyzer
(DTA) [6]. Both photoelectrons and Auger electrons were recorded for selected photon energies
from 20 eV to 140 eV above Si 2p threshold. The results indicate that when the photon energy
increases, or the nanoparticle size decreases, the electron angular distribution becomes more
isotropic, while the observed forward/backward asymmetry does not show a strong dependence
on the electron kinetic energy. By comparing these results with numerical simulations, we could
qualitatively explain the asymmetry as being due to the attenuation of the X-ray beam inside the
nanoparticle and the electron escape depth from the particles and propose a method to
characterize chemical composition and size of nano-objects.
In a second study, we used a focused beam of Si-nanocrystals from a stable suspension in
ethanol. All the oxidation states of silicon from Si0 to Si4+ are present in our XPS spectra,
denoting a shallow transition between the Si-core and the oxide shell of the particle. Moreover
clear shifts of the whole XPS spectrum are observed towards higher binding energies as
oxidation time increases, which could reveal strong interfacial Si/SiO2 interaction and
compressive stress arising upon oxidation. Complementary studies on the same samples using
High-Resolution Transmission Electron Microscopy (HR-TEM), Fourier-Transform Infrared
spectroscopy (FTIR), and tabletop XPS measurements of deposited samples have also been
performed. Finally, the importance of studying isolated nano-sized particles will be highlighted.
13. Dr. Ovidiu Crisan - "Surface functionalized core-shell nanoparticles si nanoclusters"
Dr. Ovidiu Crisan is Senior Scientist I in the Department of Magnetism and
Superconductibility of NIMP.
A novel method for production of metal clusters as building blocks for nanoscale devices is
reported and its advantages for nanoelectronics and biomedical applications are highlighted. The
method, which is a derivative from the wider range of techniques called the gas / cluster
207
aggregation methods, is suitable to synthesise nano-clusters of various nature (metallic, oxides,
hybrid core-shell architectures) in a wide range of sizes, from submonolayers (few hundreds of
atoms clusters) to continuous thin films. More important, these clusters may be subsequently
modified and functionalized in-situ by adding atoms/molecules of different nature, on the surface
of readily formed clusters. The cluster size is extremely well controlled by the vapor pressure of
the picked-up species. Moreover, the method is versatile, since it allows multiple pick-up
processes within the same rare gas cluster for producing, for example, core-shell nanoparticles
with metal core and non-metallic shell or vice-versa, nano-onions, with different species
successively attached to the surface of the initial picked-up cluster, and so on. Initial formation
of Fe gas-stabilised clusters and core-shell nanoparticles with Fe core and Fe oxide shell, as well
as their structure and morphology, are presented and discussed. The core-shell nanoparticles
show incipient self-organization into hexagonal cluster superlattice. Structural, magnetic and
Mössbauer spectroscopy investigations have been performed on the Fe cluster samples. The
magnetic properties of supported Fe clusters show marked differences compared to the bulk. A
small hysteresis is observed in the parallel applied field while in the perpendicular case, lack of
saturation at the highest applied field is noticed. Such behavior has also been observed and
interpreted in FeRh and AgCo bimetallic nanoparticles or core-shell Fe-C nanoclusters. This
behaviour marks the occurrence of a strong planar magnetic anisotropy in the sample and may
also be a consequence of increased surface spin disorder and finite size effects, which are typical
for nanoparticles in the reported size range. Molecular species such as antibodies, aptamers or
other radicals with molecular recognition properties can be attached in situ at the latest stage of
pick-up process, such hybrid organo-metallic cluster having outstanding prospective applications
in biomedical fields such as drug delivery or targeted tumour therapy.
14. Dr. Nicolae M. Albu - " Brownian Dynamics Model of Excited-State Relaxation and Charge
Mobility on Conductive Polymers in Solution "
Dr. Nicolae Albu just achieved his PhD work at the Department of Chemistry, Carnegie
Mellon University, Pittsburgh, PA
The flexibility of conjugated polymers is essential for their high processability yet introduces
disorder that plays a central role in establishing their electronic properties. This disorder is
dominated by the torsional degrees of freedom between the conjugated aromatic rings. The
rotational barrier for these torsions is low when the polymer is in the ground electronic state.
However, the presence of an exciton (in the case of excited state relaxation) or a charge (in the
case of charge mobility) substantially increases the torsional barrier in the vicinity of the exciton
or charge. The dynamics are then dominated by this tendency of an exciton or charge to self-trap
and planarize a local region of the polymer chain. We will present an approach that couples a
simple site- hopping model for the exciton or charge to a stochastic model of the solvent.
208
For excited state relaxation, we examine the excitation as a function of time following initial
creation of the excited state. The results show double exponential decay, with time scales that
differ by up to an order of magnitude. The difference between the time scales increases with
chain length, becoming resolvable for chains with about 5 aromatic rings and saturating by about
20 aromatic rings. Comparisons are made to a much simpler model in which the excited state is
modeling as an increase in torsional potential that is uniform between all rings. This simpler
model also shows double exponential relaxation, indicating that the origin of the two time scales
is not a result of the localization associated with self-trapping of the exciton.
The charge mobility of single polymer chains in solutions is experimentally measured via
microwave reflectivity. In current models, the charge is localized initially on a single repeat unit
of the polymer and the torsional angles are frozen during the simulation. Our approach instead
assumes rapid electronic dephasing, such that mobility reflects the motion of the planarized
region associated with the charge along the polymer chain. The mobilities obtained from this
model are consistent with experiment, suggesting that the charge mobility in solution is strongly
influenced by solvent dynamics and so is not a direct measure of the intrinsic mobility.
15. Dr. Sorin Vizireanu - "Carbon nanowalls: plasma synthesis, properties and applications"
Dr. Sorin Vizireanu works in the Department of Low Temperature Plasma Physics and
Applications from the National Institute of Lasers, Plasma and Radiation Physics
Dr. Vizireanu's talk concentrated on the description and outlook of applications of a novel
system which was synthesized for the first time in the laboratory lead by CS1 Dr. George
Dinescu: layers presenting nano-walls of carbon, composed by a few graphene layers
perpendicular to the substrate. Besides the fundamental interest, these structures present a strong
applicative potential based on the accurate control of hydrophilic and hydrophobic properties in
view of applications in the area of lab-on-chips. Correlated studies were shown of scanning
electron microscopy, photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy
and contact angle measurements, presenting different synthesis routines and the effects of posttreatment of carbon nanowall samples, particularly discharges in different gases. It was shown
how actually a quite accurate control of hydrophilic properties may be achieved by these postprocessing plasma treatments.
16. Dr. Ionel Popa - "Colloidal interactions and mechano-elastic properties of proteins and
polymers studied by using atomic force microscopy"
Dr. Ionel Popa is actually Post-doctoral fellow, Fernandez Laboratory, Columbia University,
New York
Inter- and intramolecular forces are the basic bricks of matter organization, and their additive
effect is of prime importance. For example, a polypeptide chain connected by covalent bonds and
209
interacting by hydrogen bonds is structured in a specific shape, forming what is commonly
designed as a protein. The specific shape allows any protein to fulfill its specific attributions
inside a cell. The presentation was structured in three parts. Firstly, an overview will be given on
the measurement of van der Waals and electrostatic forces by using atomic force microscopy
(AFM) together with a newly developed technique, based on coloidal probes. This technique
allows one to obtain an ensambly image of the forces that various covalent bonds can support
before their homolytical breakout. The study of covalent bonds under force is possible by using
mechanical protein denaturation as a fingerprint and a new covalent attachment on the binding
surfaces. In the last part, some aspects are outlined regarding protein de-structuring under the
effect of mechanical forces at a single molecule level and an unitary view of the way the
molecule change their physical structure is presented.
During the final discussion, the organizer, Dr. C.M. Teodorescu draws the conclusion that the
workshop was highly useful, it contributed strongly to the fostering of existing collaborations
and to the formation of new ones, especially in view of the new experimental facilities
operational at NIMP.
II.Workshop "Materials in extreme conditions: processing, characterization and
applications" September 26-27, 2012 (Chair: Dr. Petre Badica)
The workshop had 29 participants, 17 from Romania and 12 scientists working abroad. We
mention among the participants: A. Jianu (Karlsruhe Institute for Technology, Karlsruhe,
Germany), T. Retegan (Chalmers University, Gothenburg, Suedia), D. Axinte (University
of Nottingham, UK), M. Tomut (GSI Darmstadt, Germany), L. Zigoneanu (Department of
Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708,
USA), M. Calin (Institute for Complex Materials, Leibniz Institute for Solid State and
Materials Research , Dresden, Germany),J. Groza (Univ. California Davis, USA).
210
211
INTERNATIONAL
COOPERATION
INTERNATIONAL COOPERATION PROJECTS
2 FP7 projects
Pintilie I.
FP7 European Project
Marie Curie Training Network on Particle Detectors (MC-PAD)
No: 214560-2
Partners: CERN- European Organization for Nuclear Research (CH), DESY- Stiftung Deutsches
Elektronen-Synchrotron (DE), GSI- Gesellschaft für Schwerionenforschung mbH (DE), JSIJožef Stefan Institute (SI), AGH- AGH University of Science and Technology (PL), LNFLaboratori Nazionali di Frascati - Istituto Nazionale di Fisica Nucleare (IT), NIKHEF- Stichting
voor Fundamenteel Onderzoek der Materie (NL), PSI- Paul Scherrer Institut (CH), UHHUniversity of Hamburg (DE), EVATRONIX- Evatronix SA (PL), IFJ PAN- Instytut Fizyki
Jadrowej im. Henryka Niewodniczanskiego Polskiej Akademii Nauk (PL), MICRON- Micron
Semiconductor Ltd. (UK), Photonis- Photonis SAS Holding (F) (http://mc-pad.web.cern.ch/mcpad/ )
2008-2012
Pintilie L.
Large-scale integrating project Interfacing Oxides (IFOX)
NMP-2009-2.2-1
Coordinator: Theo Rasing (Radboud University, Nijmegen)
Scientific coordinator: Georg Schmidt (Martin-Luther-Universität,Halle-Wittenberg)
Partners: Radboud University Nijmegen ( NL), Martin-Luther-Universität Halle Wittenberg
(DE), Max Planck Gesellschaft zur Foerderung der Wissenschaften E.V. (MPI-HALLE) (DE),
University of Glasgow ( UK ), Centro Ricerche Fiat SCPA (IT), Universiteit Antwerpen (BE),
Paul Scherrer Institut (CH), National Institute of Materials Physics (NIMP) (RO), IBM Research
GMBH ( CH), Universitat Konstanz (DE), Institute for Nanostructured Materials Bologna (IT),
Intel Performance Learning Solutions Limited ( IE), Forschungszentrum Jülich GmbH ( DE ),
Twente Solid State Technology ( NL), Georg August Universitaet Goettingen (DE) ,Holy Trinity
College Dublin (IE), Organic Spintronics srl ( IT), Universiteit Twente (NL)
212
1 project CERN
Pintilie I.
CERN –RD50 (Partners: 48 research institutions;27 countries from Europe, USA, Canada
(http://rd50.web.cern.ch/rd50/))
Radiation hard semiconductor devices for very high luminosity colliders
2001-2012
2 projects Romanian Swiss Research Program RSRP
Crisan O.
Novel FePt-based hard magnetic materials for sustainable energy applications
Project 6 / 2012-2015
Partner: Swiss Federal Laboratories for Materials Science and Technology, EMPA Thun Elvetia
Baibarac M.
Electrochemical functionalization of carbon nanotubes with heteropolyanions and conjugated
polymers and the elucidation of interactions at the carbon nanotubes/ heteropolyacid/ conjugated
polymer interface
Partners: Ecole Polytechnique Fédérale de Lausanne, Switzerland and Institute for Problems of
Materials Science of National Academy of Science of Ukraine
3 proiecte CEA
Pintilie L.
RF Components Laboratory, CEA-LET Grenoble, France
Investigation of metal-ferroelectric interface at macro- and nanoscale
Contract no. C1 09/2010
2010-2013
Teodorescu C.M.
Service de Physique et Chimie des Surfaces et Interfaces, Institut Rayonnement Matière
Saclay, Commissariat à l'Energie Atomique, France
Ferroelectric and diluted magnetic semiconductor based multiferroic heterostructures for energy
applications
IFA-CEA Project No. C1-08/2010.
2010-2013
Predoi D.
213
Institut de Chimie Séparative de Marcoule - UMR 5257
Development and characterization of solid apatite matrices capable of storing inorganic
pollutants: structure and adsorption processes.
IFA-CEA Project No. C2-06/2011.
2012-2015.
1 project ANR-ANCS
Teodorescu C.M.
Institut Rayonnement Matière de Saclay, Commissariat à l'Energie Atomique, France
Chemical switching of surface ferroelectric topology
2012-2014
Partnership IUCN Dubna
Kuncser V.
Complex characterization of multilayered magnetic films by neutron scattering and
complementary techniques
Protocol Romania - IUCN:: 4134-4-2012/2014.
2012-2014
Partnership Japan Society for the Promotion of Science
Plugaru N.
Modeling the Properties of Porous Silicon -Based Systems from First Principles Electronic
Structure.
2012-2014
Other European Projects
Baibarac M.
SCOPES Project No. IZ74Z0_137458/2012
Implementation in East Europe of new methods of synthesis and functionalization of carbon
nanotubes for applications in the energy storage and sensors field
2011- 2014
Enculescu I.
EUROC-5/2011
Insect Odorant-Binding Proteins on Conductive Polymer Nanofibers Based Biosensor to
Diagnose Crop
2011-2013
214
Sârbu C.
Programul MAT-HHFM al EFDA (European Fusion Development Agreement)
Partnership with cu 3 national Euratom associations: netherlands (NRG-Petten), Portugal
(IPS_Lisbon) and Spain (CEIT-San-Sebastian)
Ultramicroscopy and nano-scale composition analysis of pure-W and ODS-W-alloys and of final
parts made of W-alloys by MIM/PIM technology
2 COST actions
Teodorescu C. M.
COST MP 0805
Novel Gain Materials and Devices Based on III-V-N Compounds
2008-2012
Pintilie L.
COST action SIMUFER (COST MP0904)
Single- and multiphase ferroics and multiferroics with restricted geometries
Action Coordinator: Prof. Liliana Mitoseriu
http://www.cost.eu/domains_actions/mpns/Actions/MP0904
2010-2014
2 Projects Erasmus
Predoi D.
Institut des Sciences de la Terre d’Orléans, UMR 6113 CNRS – Université d’Orléans
Biogeochemistry of iron in surface environments,
ERASMUS
2009-2013.
Predoi D.
Universite Bordeaux 1
Surface properties of iron oxide nano-particles for biomedical applications,
ERASMUS
2009-2013.
EURATOM PROJECTS
Galatanu A.
215
Production by powder metallurgy procedures of W-FGM-steel components
BS-M3/2012
Galatanu A.
Welding and brazing W-W and W-steel by SPS
BS-M3A/2012
Galatanu A.
Complex composite materials W-SiC
BS-M3B/2012
Kuncser V.
Complex characterization of films based on Be, W, C for fuel retention
BS-M5/2012
Mihalache V.
Optimizing of chemical composition and preparation process of ODSFS based on FeCr
precipitation hardened
BS-M7/2012
Badica P.
Laboratory preparation and characterization of nanostructured ODSFS samples produced by
plasma arc sintering
BS-M8/2012
AGREEMENTS
Badica P.
Superconducting nanocomposites based on Magnesium diboride with improved pinning SuperNano-MgB2
Contract 505/2010 (2011/2012)
China
Badica P.
Oxide whiskers: growth, characterization and as tips for STM” - ACEOX
Contract 507/2010 (2011/2012)
China
Secu M.
Study of Down- Conversion Quantum Cutting Effects on Doped Glasses for Better Exploitation
of the Solar Spectrum
China
216
Stănculescu A.
Organic structures on conductive organic substrates for optoelectronic and photovoltaic
applications
France
Crişan O.
New magnetic systems with low dimensionality
India
Tomescu A.
Complex investigations of semiconducting oxidic materials of p type with application potential
Germany
BILATERAL COOPERATION PROJECTS
Cernea M.
Institute for Science and Technology of Ceramics (ISTEC), Faenza, Italy
Lead free piezoelectric materials processed by wet chemical routes (MPPC
2010-2013
Ciurea M. L.
Cankaya University, Ankara, Turkey
Modelling and simulation: transport phenomena in
2008-2013
nanostructures (0D, 1D and 2D)
Ciurea M. L.
Belarusian State University, Minsk , Byelarus
Hall investigations on irradiated Si and SiGe bulk materials
2010-2013
Crisan A.
Nanoelectronics Research Institute of AIST Tsukuba, Japan
Comprehensive Agreement on Joint Scientific Cooperation in the field of Science and
Technology of Advanced Materials
2007-2012
Crisan O.
Programme Hubert Curien PHC “ Brancusi”: ANCS – CNRS
Universite du Maine, Le Mans, Franta
Hard magnetic nanocrystalline materials obtained from amorphous precursors
2013-2014
217
Kuncser V.
University of Duisburg, Germany
Interphase mechanisms in thin layer compounds and composites
2007-2012
Moldoveanu V.
Science Institute Dunhaga 3, 107 Reykjavik, Iceland
Time-dependent transport in interacting open systems: theory & modeling
Permanent
Moldoveanu V.
Physics Department, Bilkent University, Ankara, Turkey
Correlated transport in parallel quantum dots
Permanent
Pasuk I.
University of Cyprus, Nicosia, Cyprus
Cuprates thin films
Permanent
Predoi D.
Le Havre University France
Ultrasonic characterization of bio-ceramics powders and fero-fluids
2007-2012
Predoi D.
University of Bordeaux I, France
Magnesium based nanocomposites for hydrogen storage and Fe oxide colloids
2005-2012
Stan G.E.
University of Aveiro, Department of Materials and Ceramic Engineering, CICERO,
Aveiro, Portugal
Development of a new generation of highly biocompatible dental titanium implants
functionalized by sputtering techniques with novel bioactive glass materials
2012-2014
218
NIMP FUNDING
Core Programme
Ideas
Human Ressources
Partnerships
Capacities
International Projects
Economic Contracts
TOTAL
4.936.609 Euro
2.250.313 Euro
448.900 Euro
743.838 Euro
44.145 Euro
475.230 Euro
80.889 Euro
8.979.924 Euro
219

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