HEAD: Dr. MIHAIL FLORIN LAZARESCU E

Transcription

NATIONAL INSTITUTE OF MATERIALS PHYSICS* ANNUAL REPORT 2004
Laboratory of Advanced Materials for Special Applications
HEAD: Dr. MIHAIL FLORIN LAZARESCU
E-mail: [email protected]
Tel : (+4021) 493 01 95
Fax :(+4021) 493 02 67
TOTAL EMPLOYEES: 18
A. GROUP OF CRYSTAL GROWTH AND CRYSTAL CHARACTERIZATION
HEAD: Dr. MIHAIL FLORIN LAZARESCU
Tel : (+4021) 493 01 95
Fax :(+4021) 493 02 67
RESEARCH TEAM : 7
1. Dr. Mihail Florin LAZARESCU
2. Dr. Adrian Stefan MANEA
3. Dr. Constantin LOGOFATU
4. Dr. Marin CERNEA
5. Dr. Rodica GHITA
6..Drd. Constantin NEGRILA
7. Florica UNGUREANU
senior researcher II
senior researcher III
assistant researcher
B. GROUP OF PHYSICS OF HIGH FREQUENCY MATERIALS AND DEVICES
HEAD: Dr. ANDREI IOACHIM
E-mail: ioachim@ infim.ro
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
RESEARCH TEAM: 7
1. Dr. Andrei IOACHIM
2. Dr. Marian Gabriel BANCIU
3. Drd. Liviu NEDELCU
4. Dragos GHETU
5. Constantin Augustin DUTU
6. Marian IOSIF
7. Alexandru GAVRILA
engineer
engineer
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PRESENT RESEARCH INTERESTS:
1.
2.
3.
4.
5.
6.
7.
8.
9.
The surface/interface study (by non linear optics - SHG and impedance spectroscopy
methods) of n-GaAs and p-GaAs in electrolyte media. Contributions of the surface
states on the optical and electrochemical properties of the semiconductor/electrolyte
interfaces (Ref 1, 2, 3);
Synthesis and characterization of Heussler alloys with a new molar ratio/composition
(Ref. 4, 5, 6, 7, 8);
The application of the sol-gel and magnetron plasma deposition methods in the fields
of nanometric thin films preparation for the obtaining of semiconductor/semiconductor
structures or others (based on piezomaterials) (Ref. 9, 10);
Τechniques and methods for the synthesis of highly homogeneous magnetic alloys
containing a volatile component (e.g. magnesium) in “extreme” conditions (under high
pressure of inert pure gases);
Research and development of high-k dielectric and ferroelectric materials for
microwave applications (BZT, ZST, BNT, BST) (Ref. 11-15);
Development of reciprocal and non-reciprocal microwave components;
Investigation of the dielectric and magnetic loss mechanisms in ceramic and composite
materials;
Computational electrodynamics and improved FDTD methods for accurate 3-D design
of microwave devices (Ref. 16);
Development of new type of compact resonators and filters for mobile
communications.
MAIN SCIENTIFIC RESULTS OBTAINED IN 2004:
1. Magnetic and semimagnetic alloys obtaining methods
A wide class of bulk intermetallic compounds and alloys were prepared for the use in some
fields of big interest : spintronics, hydrogen storage, and others. Synthesis under high pressure
of inert pure gas has been performed and a special graphite set up/vessel was built for this
purpose. Highly homogeneous structures of the bulk materials was obtained
2. Ferroelectric solid solutions (Ba,Sr)TiO3 for microwave applications
Barium strontium titanate (BST), ternary ceramic compounds with the molar formula
(Ba1−xSrx)TiO3, were prepared by solid-state reaction. Four compositions with x = 0.25, 0.50,
0.75 and 0.90, have been studied. Samples with two type of thermal treatment at 1230 and
1260 oC have been manufactured and analyzed. Dielectric measurements have been performed
at low and high frequencies. The increasing concentration of Sr ion leads to the shift of the
Curie point below room temperature. Experimental data show a linear decrease of the Curie
point TC (oC) ≈ 120–360x, versus the strontium fraction x. Dielectric loss of 10−3 at 1 GHz
shows that this ceramic material is quite suitable for high frequency device applications.
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3. Studies on ZST ceramics for microwave and millimeter wave applications
Ternary system ZrO2–SnO2–TiO2 was studied for applications in microwave domain.
Structural and dielectric properties were investigated in correlation with technological
parameters (sintering temperature, sintering time etc.) for ZST based ceramics. Dielectric
resonators from ceramics with εr ∼ 36 and Q·f product 50.000 – 60.000 were obtained from
microwave up to 115 GHz. Substrates for hybrid microwave circuits was also obtained
(1"x1").
4. BNT ceramic synthesis and characterization
Investigations on barium neodymium titanate (BNT) prepared by solid state reaction was
performed. The samples were sintered at temperatures, Ts, in a range 1200–1300 oC.
A decrease of the Curie temperature with the increase of the Nd2O3 concentration was
observed. For the sample with 28 wt.% Nd2O3, 0.5 mol PbO, pyroelectric data indicate Curie
temperature around 75 K, therefore, at room temperatures, the materials are in paraelectric
phase. Ceramic materials with εr = 60 ÷ 70 and low loss up to 5÷6 GHz were obtained and are
suitable for applications as dielectric resonators. Materials with high density and adequate
microwave characteristics were obtained by adding 0.5 mol PbO substitutional for BaO. BNT
ceramics with high Nd2O3 concentration (28 wt.%), sintered at 1250 oC for 2 h are attractive
for dielectric resonators for frequencies up to 3 GHz (εr = 80 ÷ 90 and tanδ = 5·10-4).
5. Wireless compact filters designs by using an improved FDTD method
An accurate 3-D FDTD method was developed in order to design new resonators and filters.
Due to the developed acceleration techniques, the FDTD method is five times faster than a
conventional FDTD method. GSM / GPRS filters for 900 MHz bandwidth were developed by
cross-coupling new type of planar resonators, which occupy down to 32% of the surface area
of a folded half-wavelength resonator. The filters exhibit an improved selectivity due to the
quasi-elliptic response. The design method can be easily extended to other frequency bands of
mobile communications.
INTERNATIONAL COOPERATIONS:
-Project title : FENIKS (FP 5): “Study on the half-metallic alloy (NiMnSb) and on
chromium oxide: characterization of the bulk and film samples
−Project title : Non linear optics at GaAs (hkl) electrodes, with financial support of the
Deutsche Forschung Gemeinschaft , partner Elektrochemie Abteilung - Universitaet ULM,
Germany
-COPBIL Project with Istituto per i Processi Chimico-Fisici C.N.R. Pisa, Italy
Project title: Materials with low dielectric and magnetic losses at microwave
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frequencies (2000-2004)
-Bilateral agreement with University of New South Wales, Sydney, Australia
Project title: New RF and microwave devices (2001-2004)
PAPERS PUBLISHED OR ACCEPTED FOR PUBLICATION IN 2004 :
1. V.Lazarescu, M.F.Lazarescu, H.Jones, W.Schmickler, "Second Harmonic Generation at
the GaAs (111)-B/solution interfaces", J.Electroanalitical Chemistry 567 (2), p.257-261,
(2004)
2. V.Lazarescu, M.F.Lazarescu, E.Santos, W.Schmickler, "Second Harmonic Generation and
impedance spectroscopy at n-GaAs (100) electrodes", Electrochimica Acta , 49/24, p.42314238, (2004)
3. V.Lazarescu, R.Scurtu, M.F. Lazarescu, H.Jones, W.Schmickler, “Field effects and
surface states in SHG at n-GaAs (hkl) electrodes”, accepted for the publication in
Electrochimica Acta
4. C.E.A.Grigorescu, J.Trodahl, N.MStrickland, A.Bittar, S.A.Manea, J.Giapintzakis,
O.Monnereau, R.Notonier, V.J.Kennedy “Minority-spin band parameters in a NiMnSb thin
film determined by spectral conductivity”, Journal of Applied Physics, 96(11), p.6421-6424,
(2004)
5. Y.Miyoshi, Y.Bugoslavsky, S.K.Clowes, W.R.Branford, C.E.A.Grigorescu, S.A.Manea, O.
Monnereau, L.F.Cohen “Spin polarisation of the transport current at the free surface of bulk
NiMnSb”, Phys.Rev B 69, 214425, p.214425-1 – 214425-5, (2004)
6. E.Valerio, C.E.A.Grigorescu, S.A.Manea, F.Guinneton, W.R.Branford, M.Autric “Pulse
Laser deposition of various full- Heusler alloys Co2MnX(X=Si, Ga, Ge, Sn, SbSn) thin films at
moderate temperature”, accepted for the publication in Thin Solid Films (Sept. 2004)
7. S.A.Manea, O. Monnereau, R.Notonier, F.Guinneton, C.Logofatu, L.Tortet, A.Garnier, M.
Mitrea, C.Negrila, W.Branford, C.E.A.Grigorescu, “Heussler bulk materials as targets for
pulsed laser deposition: growth and characterization”, accepted for the Journal of Crystal
Growth proof (2004) –online www.sciencedirect.com
8. C.E.A.Grigorescu, E.Valerio, L.Tortet, R.Notonier, H.J.Trodahl S.A.Manea, M.Autric,
“Co2MnX (X=Si,Ge, SbSn) thin films grown by pulsed-laser deposition: morphology and
optical properties”, accepted for the J. Crystal Growth, proof (2004)-online
www.sciencedirect.com
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9. M.Cernea, A.Ianculescu, O.Monnereau, L.Argème, V.Bley, B.Bastide, C.Logofatu,
“Preparation and characterization of Ce-doped BaTiO3 thin films by pulsed laser deposition”,
J. Materials Science, 39, [8], p. 2755-2759, (2004)
10. O.Monnereau, M.Cernea,
L.Tortet, A.Garnier,
R.Notonier, S.A.Manea,
C.E.A.Grigorescu, "X-ray diffraction and microscopy investigations of structural
inhomogeneities in NiMnSb crystallised from the melt", J. Phys. IV France 118, p.343-350,
(2004)
11. H.V.Alexandru, C.Berbecaru, A.Ioachim, M.I.Toacsan, M.G.Banciu, L.Nedelcu, D.
Ghetu, “Oxides ferroelectric (Ba,Sr)TiO3 for microwave devices”, Materials Science and
Engineering B 109, p.152-159, (2004)
12. A.Ioachim, M.I.Toacsan, M.G.Banciu, L.Nedelcu, H.V.Alexandru, C.Berbecaru, D.
Ghetu, G.Stoica, “BNT ceramics synthesis and characterization”, Materials Science and
Engineering B 109, p.183-187, (2004)
13. A.Ioachim, M.G.Banciu, M.I.Toacsen, L.Nedelcu, D.Ghetu, H.V.Alexandru, G.Stoica,
G. Annino, M.Cassettari, M.Martinelli, “Nickel-doped (Zr0.8, Sn0.2)TiO4 for microwave and
millimeter wave applications”, accepted for Materials Science and Engineering B
14. V.Alexandru, C.Berbecaru, F.Stanculescu, A.Ioachim, M.G.Banciu, M.I.Toacsan, L.
Nedelcu, D.Ghetu, “Ferroelectric solid solutions (Ba,Sr)TiO3 for microwave applications”,
accepted for Materials Science and Engineering B
15. M.Nistor, F.Gherendi, M.Magureanu, N.B.Mandache, A.Ioachim, M.G.Banciu, L.
Nedelcu, H.V.Alexandru, “(Zr, Sn)TiO4 thin films for applications in electronics”, accepted
for Applied Surface Science
16 M.G.Banciu, G.Lojewski, L.Nedelcu, D.Ghetu, N.Militaru, D.Brinaru, T.Petrescu,
“Design of small-size planar filters using FDTD and wavelet analysis”, Buletinul Stiintific al
Universitatii “Politehnica” din Timisoara, Seria Electronica si Telecomunicatii, Tomul 49(63),
Fascicola 2, 2004, ISSN 1583-3380”, p.285-288
CONFERENCES :
1. V.Lazarescu, R.Scurtu, M.F.Lazarescu, H.Jones, W.Schmickler, “Field efffects and
surface states in SHG at n-GaAs (hkl) electrodes”, presented at the 54th Congress ISE- 20-24
September, 2004, Salonic-Greece
2. C.E.A.Grigorescu, E.Valerio, L.Tortet, H.J.Trodahl, A.S.Manea, M.Autric. “Co2MnX
(X=Si,Ge, SbSn) thin films grown by pulsed-laser deposition: morphology and optical
properties” presented at the 14th Int. Conf on Crystal Growth, Grenoble 9-13 Aug. 2004
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3. S.A.Manea, O.Monnereau, R.Notonier, F.Guinneton, C.Logofatu, L.Tortet, A.Garnier,
M.Cernea, M.Mitrea, M.F.Lazarescu, C.Negrila, C.E.A.Grigorescu, “Heussler and halfHeussler bulk materials growth and characterization”, presented at the 14th Int. Conf on
Crystal Growth, Grenoble 9-13 Aug. 2004
4. M.Balaceanu, M.Braic, V.Braic, F.Ionescu, C.Logofatu, C.Negrila, M.Cernea “Surface
chemistry of plasma deposited ZrC hard coatings”, presented at Seventh European
Conference on Atomic& Molecular Physics of Ionized Gases-ESCAMPIG 17, 1-5 September
2004, Constanta-Romania
5. R.V.Ghita, D.Pantelica, M.F.Lazarescu, S.A.Manea, C.Logofatu, C,Negrila, V.Ciupina,
“Au-Ti thin films deposited on GaAs”, presented at 5th International Balkan Workshop on
Applied Physics, July 5-7, 2004, Constanta, Romania;
6. A.Ioachim, M.I.Toacsan, M.G.Banciu, L.Nedelcu, D.Ghetu, H.V.Alexandru,
C.Berbecaru, G. Stoica, “Effect of Sr content on dielectric properties of (Ba,Sr)TiO3
ferroelectric ceramics”, Proceedings of XVII International Conference on Electromagnetic
Fields and Materials, EMFM 2004, Warszawa, Poland, p. 73-77
7. A.Ioachim, M.I.Toacsan, M.G.Banciu, L.Nedelcu, D.Ghetu, H.V.Alexandru,
C.Berbecaru, G.Stoica, “Dielectric characterization of some ceramics in the ternary system
BaO-Nd2O3-TiO2”, Proceedings of XVII International Conference on Electromagnetic Fields
and Materials, EMFM 2004, Warszawa, Poland, p.78-82
8. A.Ioachim, M.G.Banciu, M.I.Toacsen, L.Nedelcu, D.Ghetu, H.V.Alexandru, G.Stoica,
G. Annino, M.Cassettari, M.Martinelli, “Nickel-doped (Zr0.8, Sn0.2)TiO4 for microwave and
millimeter wave applications”, E-MRS 2004 Spring Meeting, May 2004, Strasbourg, France
9. M.Nistor, F.Gherendi, M.Magureanu, N.B.Mandache, A.Ioachim, M.G.Banciu,
L.Nedelcu, H.V.Alexandru, “ (Zr, Sn)TiO4 thin films for applications in electronics”, E-MRS
2004 Spring Meeting, May 2004, Strasbourg, France
10. H.V.Alexandru, C.Berbecaru, F.Stanculescu, A.Ioachim, M.G.Banciu, M.I.Toacsan, L.
Nedelcu, D.Ghetu, “Ferroelectric solid solutions (Ba,Sr)TiO3 for microwave applications”,
E-MRS 2004 Spring Meeting, May 2004, Strasbourg, France
11. L.Cosereanu, A.Szilagyi, A.Ioachim, M.I.Toacsan, M.G.Banciu, L.Nedelcu, D.Ghetu,
G. Stoica, “Miniature radiating element for an adaptive antenna area used in electronic
warefare”, Proceeding of the 35th International Scientific Symposium of the Military
Equipment and Technologies Research Agency, May 2004, Bucharest, Romania, Vol I, p. 355358
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12. M.G.Banciu, G.Lojewski, T.Petrescu, A.Ioachim, L.Nedelcu, R.Cacoveanu, N.Militaru,
D. Brinaru, D.Ghimpeteanu, “Small-size filters with improved characteristics for wireless
comunications”, Proceeding of the 35th International Scientific Symposium of the Military
Equipment and Technologies Research Agency, May 2004, Bucharest, Romania, Vol I, p. 437440
13. L.Cosereanu, A.Ioachim, A.Szilagyi, “Time-frequency representation used in radar
electronic warefare applications” Proceeding of the 35th International Scientific Symposium of
the Military Equipment and Technologies Research Agency, May 2004, Bucharest, Romania,
Vol I, p. 359-364
14. A.Ioachim, M.G.Banciu, M.I.Toacsen, L.Nedelcu, D.Ghetu, H.V.Alexandru, C.
Berbecaru, G.Stoica, “Effect of aditives on microwave dielectric properties of (Zr,Sn)TiO4
ceramics”, The 5 th International Balcan Workshop on Applied Physics, Constanta, Romania,
July 2004
15. A.Ioachim, M.I.Toacsen, M.G.Banciu, L.Nedelcu, D.Ghetu, H.V.Alexandru, C.
Berbecaru, G.Stoica, “Effect of additives on microwave dielectric properties of (Zr, Sn)TiO4
ceramics”, The 5 th International Balcan Workshop on Applied Physics, Constanta, Romania,
July 2004
16. A.Ioachim, “High permittivity dielectric materials for high frequency applications”, The 5
th
International Balcan Workshop on Applied Physics, Constanta, Romania, July 2004
17. M.G.Banciu, G.Lojewski, A.Ioachim, N.Militaru, L.Nedelcu, D.Brinaru, D.Ghetu,
T.Petrescu, “Compact filter design using wavelet processing of the FDTD signal”, The 5th
International Balkan Workshop on Applied Physics, Constanta, 5-7 iulie 2004
18. C.Berbecaru, F.Stanculescu, S.Antohe, H.V.Alexandru, A.Ioachim, M.G.Banciu,
L.Nedelcu, D.Ghetu, “Solid solutions for microwave applications”, The 5th International
Balkan Workshop on Applied Physics, Constanta, 5-7 iulie 2004
19. M.G.Banciu, G.Lojewski, A.Ioachim, L.Nedelcu, N.Militaru, A.Shen, R.Ramer, “New
planar compact dual mode filters for mobile comunications”, Proceedings of the 27 th
International Semiconductor Conference, CAS 2004, Sinaia, Romania, October 2004, Vol. 1,
p. 137-140
20. A.Ioachim, M.G.Banciu, M.I.Toacsen, L.Nedelcu, D.Ghetu, G.Stoica, G.Annino,
M.Cassettari, M.Martinelli, “Dielectric ceramics based on the ZrO2-SnO2-TiO2 ternary system
for microwave and millimeter wave applications”, Proceedings of the 27th International
Semiconductor Conference, CAS 2004, Sinaia, Romania, October 2004, Vol 2, p. 423-426
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21. C.Berbecaru, H.V.Alexandru, M.Negoita, A.Balabaneanu, F.Stanculescu, A.Ioachim,
M.G. Banciu, L.Nedelcu, D.Ghetu, “(Ba, Sr)TiO3 solid solutions for microwave
applications”, Sesiunea Anuala de Comunicari Stiintifice a Facultatii de Fizica, Universitatea
din Bucuresti, 28 mai 2004
22. A.Ioachim, M.G.Banciu, M.I.Toacsen, L.Nedelcu, D.Ghetu, H.V.Alexandru,
C.Berbecaru, G.Annino, M.Cassettari, M.Martinelli, G.Stoica, “Doped (Zr,Sn)TiO4 ceramics
for microwave and millimeter waves applications”, Conferinta Nationala de Fizica, Pitesti,
Romania, septembrie 2004
23. M.G.Banciu, G.Lojewski, L.Nedelcu, N.Militaru, D.Ghetu, T.Petrescu, “Improved
FDTD design of compact RF filters”, Conferinta Nationala de Fizica, Pitesti, Romania,
septembrie 2004
24. A.Ioachim, M.G.Banciu, M.I.Toacsen, L.Nedelcu, D.Ghetu, H.V.Alexandru,
C.Berbecaru, "High dielectric constant materials for microwave and millimeter waves
applications", Proceedings ale celei de-a IX-a Sesiuni de Comunicari Stiintifice “Stiinta si
invatamântul – Fundamente ale secolului al XXI-lea”, Academia Fortelor Terestre, Sibiu, 26
nov 2004
25. A.Ioachim, M.I.Toacsen, M.G.Banciu, L.Nedelcu, D.Ghetu, M.Feder, C.Plapceanu,
F.Lifei, “Synthesis and dielectric properties of Ba(Zn1/3 Ta2/3)O3 ceramics”, Proceedings ale
celei de-a IX-a Sesiuni de Comunicari Stiintifice “Stiinta si invatamântul – Fundamente ale
secolului al XXI-lea”, Academia Fortelor Terestre, Sibiu, 26 nov 2004
26. M.G.Banciu, G.Lojewski, N.Militaru, A.Ioachim, L.Nedelcu, D.Ghetu, D.Branaru,
T.Petrescu, “Filtres microruban compacts pour communications mobiles”, Proceedings ale
celei de-a IX-a Sesiuni de Comunicari Stiintifice “Stiinta si invatamântul – Fundamente ale
secolului al XXI-lea”, Academia Fortelor Terestre, Sibiu, 26 nov 2004
PATENTS:
Patent number. 119458 B1/2004, authors : M. Cernea, D. Neacsu, M. F. Lazarescu, A. S.
Manea, C. Logofatu,
Title : “ Carbothermal method for the preparation of BaTiO3 from BaCO3, Ti and graphite”,.
BOOKS :
Ecaterina Andronescu, Marin Cernea, Dana Neacsu, "Dielectric ceramic from nanoparticles
of barium titanate", Ed. Politehnica-Press, Bucharest, 2004.
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EDUCATIONAL ACTIVITIES :
Cernea Marin: Post-doctorate fellowship on "Synthesis of PZT material doped with Nb
and La by sol-gel method", financed by POLECER, Scientists Exchange Programme, at
Istituto di Scienza e Tecnologia dei Materiali Ceramici ISTEC-CNR-Faenza, 15 January
-14 February, 2004, Italy.
2. Negrila Catalin: European Project CONCORDE: 13 August-16 Septembrie, Institute for
Applied Chemistry,ACA-Berlin, one month 2004, Germany.
1.
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Laboratory of Low Temperature Physics and Superconductivity
HEAD: Dr. LUCICA MIU
Tel.: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 11
RESEARCH TEAM: 10
1. Dr. Lucica MIU
2. Dr. Mihai VELTER-STEFANESCU
3. Dr. Gheorghe Virgil ALDICA
4. Dr. Viorel Constantin SANDU
5. Dr. Stelian POPA
6. Dr. Adrian Ioan CRISAN
7. Dr. Petre BADICA*
8. Dr. Valentina MIHALACHE
9. Monica Maria POPA
10. Oana Genoveva DEDIU**
senior researcher I
senior researcher I
researcher
researcher
chemist
Present address:
*
IMR, Tohoku University, Sendai, Japan
**
University of Heidelberg, Germany
PRESENT RESEARCH INTEREST:
1. Superconducting materials
2. Vortex structures and dynamics
1. Superconductivity in Li2Pd3B
Superconductivity was found in Li2Pd3B below 8K [K. Togano, P. Badica et al., Phys. Rev.
Lett. 93, 247004 (2004)]. This is the first example of a boride containing alkaline metal Li.
Cubic, perovskite-like structure composed of BPd6 octahedrons, it resembles HTS, while
transport and magnetic properties are similar to classic superconductors. Expectations are
that Li2Pd3B is a ‘bridge’ between the classic superconductors and HTS. This may lead to
the discovery of a new class of superconductors and/or a better understanding of
superconductivity.
2. Vortex-like excitations above the zero-field critical temperature in the pseudogap region
In-plane angular magnetoresistivity ∆ρanisab measurements on Y1-xPrxBa2Cu3O7 single
crystals in the pseudogap region reveal that, for x ≥ 0.2, ∆ρanisab (θ) displays a deviation
from the typical quasiparticle contribution [∼sin2(θ)] for temperatures smaller than a certain
10
value Tφ in the pseudogap region. This deviation appears to be consistent with a flux-flow
type contribution to angular magnetoresistivity, and may indicate the presence of vortexlike excitations above the zero-field critical temperature in the pseudogap region [V. Sandu
et al., Phys. Rev. Lett. 93, 177005, (2004)]
3. Nonmonotonic temperature variation of the experimentally determined vortex-creep
activation energy in disordered HTS
The temperature T variation of the normalized vortex-creep activation energy U*
determined in standard magnetization relaxation experiments for Pb2Sr2Y0.53Ca0.47Cu3O8+δ
single crystals with random point disorder exhibits a maximum, which moves to lower T
values by increasing the external magnetic field oriented parallel to the c axis. The
nonmonotonic U*(T) dependence is related to the change of the vortex pinning barriers
involved in the creep process across the order-disorder transition in the vortex system
(accompanied by the occurrence of the second magnetization peak), in a dynamic scenario
[Miu et al., Phys. Rev. B 70, 134523 (2004)]. The decrease of U* with decreasing T in the
low-T region is caused by the shift of the current density J range probed in magnetization
measurements toward the critical current density, and the significant U*(J) variation in the
elastic-creep domain. The dynamic approach is confirmed by the behavior of highly
disordered top-seeded melt-grown YBa2Cu3O7−δ crystals at low T, for which no second
magnetization peak appears, and U* does not depend on T.
4. Vortex imaging
Wortex imaging and local magnetometry studies near the edge of YBCO thin films have
been performed using scanning Hall probe microscopy [A. Crisan et al., Physica C 408410, 555 (2004)]. Our data show some unusual features, namely local hysteresis inversion
and negative remnant fields, which are semi-quantitatively explained in terms of a
theoretical model of flux penetration into an infinite-long thin superconducting strip, close
to its edge.
5. Anomalies of ac susceptibility losses
superconductors
in the doped [Bi(Pb)] 2Sr2Ca2Cu3Ox
AC susceptibility measurements have been performed on Bi1.7Pb0.4Sr1.5Ca2.5Cu3.6Ox (Bi2223) samples doped with different Li-based compounds, prepared by the solid-state
reaction method [V Mihalache et al., Supercond. Sci. Technol. 17, 724 (2004)]. Asprepared samples and/or annealed in oxygen or argon, grounded or not, have been
investigated in detail in order to understand the occurrence, nature and evolution vs.
measuring parameters of the anomalous peaks observed in χ”(T) curves. We have detected
up to four peaks instead of the two peaks usually observed in the non-doped samples. It
was found that the intrinsic physical-chemical properties, such as melting temperature of
the doping compound, are not less important for the final properties of the superconductor
than their insertion properties into the crystal lattice of Bi-2223. Doping compounds with
melting temperatures below or close to the phase formation temperature of Bi-2223 phase
can act as flux, changing the growth conditions. Intensification of some processes against
others can lead to the formation of Bi-2223 phase with different properties, and thus the
different kind of pinning centers can appear, which mean more than one intra-granular
peak.
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- Project title: Preparation of HTS by nonconventional methods, Partner: University of
California, Davis, California, USA
- Project title: Normal state properties of HTS, Partner: Kent State University, Kent, Ohio,
USA
- Project title: Vortex phase diagram of MgB2 (JSPS Fellowship), Partner: Tohoku
University, Sendai, Japan
- Project title: Vortex phase diagram of disordered HTS at low temperatures.
Magnetization relaxation studies (EU TARI Program), Partner: Grenoble HMFL, France
- Project title: Vartex imaging (NATO Fellowship), Partner: Universitatea Bilkent
University, Ankara, Turkey
PAPERS PUBLISHED OR ACCEPTED FOR PUBLICATIONS IN 2004:
1.K.Togano, P.Badica, Y.Nakamori, S.Orimo, H.Takeya, K.Hirata, “Superconductivity in
metal rich Li-Pd-B ternary boride”, Phys. Rev. Lett. 93, 247004, (2004)
2.V.Sandu, E.Cimpoiasu, T.Katuwal, C.C.Almasan, S.Li, M.B.Maple, “Evidence for
vortices in Y1-xPrxBa2Cu3O7-δ angular magnetoresistivity”, Phys. Rev. Lett. 93, 177005,
(2004)
3.L.Miu, S.Popa, T.Hoji, Y.Koike, D.Miu, S.Diaz, G.Chouteau, “Nonmonotonic
temperature dependence of the experimentally determined vortex-creep activation energy
in disordered high-temperature superconductors”, Phys. Rev. B 70, 134523, (2004)
4.P.Badica, G.Aldica, A.Iyo, I.Bradea, J.Jaklovszky, “Ba:Zr=1:1 freeze-dried and
conventional chloride powders: synthesis of BaZrO3 and phase formation”, Mater. Lett.
58, 250, (2004)
5.L.Miu, “Driving-force induced disappearance of the second magnetisation peak in
Bi2Sr2CaCu2O8 + δ single crystals at low temperatures”, Physica C 405, 260, 2004
6.P.Badica, A.Iyo, G.Aldica, H.Kito, A.Crisan, Y.Tanaka, “(Cu,C)Ba2Ca3Cu4Ox-(LiF)y:
addition of LiF-an effective way to synthesize overdoped superconductor”, Supercond.
Sci. Technol. 17, 430 2004
7.P.Badica, T.Kondo, K.Togano, “Critical current density and magnetic field
irreversibility of Na0.35CoO21.3H2O superconductor”, Appl. Phys. Lett. 84, 559, (2004)
12
8.V.Mihalache, G.Aldica, P.Badica, A.Crisan, “Anomalies of AC susceptibility losses in
the doped [Bi(Pb)] 2Sr2Ca2Cu3Ox superconductor”, Supercond. Sci. Technol. 17, 724,
(2004)
9.T.Sasaki,
P.Badica,
N.Yoneyama,
K.Yamada,
K.Togano,
N.Kobayashi,
“Superconducting properties under magnetic field in Na0.35CoO21.3H2O single crystal”, J.
Phys. Soc. Jpn. 73, 1131, (2004)
10.P.Badica, K.Togano, H. Kumakura, “A modified airtight two-crucible method for
growth of Bi-2212 whiskers from glassy pellets”, Supercond. Sci. Technol. 17, 891, (2004)
11.K.Endo, P.Badica, “Infinite-layer (Ca, Sr)CuO2 films grown by MOCVD: surface
morphology and structural studies”, Physica C 408, 904, (2004)
12.P.Badica, K.Togano, S.Awaji, K.Watanabe, A.Iyo, H.Kumakura, “Application of
elevated magnetic fields during growth of BiSrCaCuO superconducting whiskers and
studies of growth defects for better understanding of the growth mechanism”, J. Cryst.
Growth 269, 518, (2004)
13.K.Endo, P.Badica, H.Sato, H.Akoh, “How to grow precipitate-free thin films suitable
for electronics devices: a new concept for the substrates”, Adv. Mat. 16, 1894, (2004)
14.P.Badica, T.Kondo, T.Kudo, Y.Nakamori, S.Orimo, K.Togano, “Magnetization
measurements on Li2Pd3B superconductor”, Appl. Phys. Lett. 85, 4433, (2004)
15.T.Kondo, P.Badica, Y.Nakamori, W.Sun, S.Orimo, K.Togano, “Influence of
atmosphere on the synthesis of MgB2 superconductor”, J. Jpn. Inst. Met. 68, 636, (2004)
16.M.Sumida, A.Matsumoto, P.Badica, H.Kumakura, “Effect of post-annealing on
superconductive properties of dip-coated Bi-2223 tapes”, Transactions of Materials
Research Society of Japan, 29, 1249, (2004)
17.K.Endo, P.Badica, T. Endo, “Similarity in the surface morphology between as-grown
(119) Bi-2223 and (103) Y-123 thin films obtained by MOCVD”, IASME Transactions 3,
586, (2004)
18.S.J.Bending, A.N.Grigorenko, A.Crisan, D.Cole, A.E.Koshelev, J.R.Clem, T.Tamegai,
S.Ooi, “Interacting crossing vortex lattices in the presence of quenched disorder”, Physica
C 412-414, 372, (2004)
19.A.Crisan, A.Pross, D.Cole, S.Bending, “Vortex imaging and local magnetization
studies in HTS by scanning Hall probe microscopy”, Physica C 408-410, 555, (2004)
20.M.Ionescu, A.H.Li, Y.Zhao, H.K.Liu, A.Crisan, “Enhancement of critical current
density in YBa2Cu3O7-δ thin films grown using PLD on YSZ(001) surface modified with Ag
nanodots”, J. Phys. D: Appl. Phys. 37, 1824, (2004)
13
21.D.Cole, A.Crisan, S.J.Bending, T.Tamegai, K.van der Beek, M. Konczykovsky, “Flux
lenses in the crossing lattices regime of layered superconductors”, Physica C 404, 99,
(2004)
22.V.Mihalache, G.Aldica, P.Badica, A.Crisan, “Anomalies of AC susceptibility losses
in the doped [Bi(Pb)] 2Sr2Ca2Cu3Ox superconductor”, Supercond. Sci. Technol. 17, 724,
(2004)
23.P.Badica, A.Iyo, H. Kito, A.Crisan, Y.Tanaka, “(Cu,C)Ba2Ca3Cu4Ox-(LiF)y: addition
of LiF as an effective way to synthesize overdoped superconductors”, Supercond. Sci.
Technol. 17, 430, (2004)
24.A.Crisan, A.Pross, S.J.Bending, R.Woerdenweber, P.Lahl, E.H.Brandt, “Vortex
trapping and anisotropic channelling in YBa2Cu3O7-δ thin films containing ordered arrays
of large antidotes”, Proceedings of European Science Foundation Workshop on
Nanostructured Superconductors, C. Jansen, P.Lahl, R.Woerdenweber, Eds., pp.24, Bad
Muenstereifel, Germany, (2004) (invited talk).
25.S.J.Bending, A.Crisan, A.Pross, A. Aziz, A.N.Grigorenko, R.G.Humphreys, “Flux
structures in mesoscopic YBaCuO square discs”, Proceedings of European Science
Foundation Workshop on Nanostructured Superconductors, C. Jansen, P. Lahl, R.
Woerdenweber, Eds., pp.86, Bad Muenstereifel, Germany, (2004)
26.P.Badica, A.Iyo, G.Aldica, H.Kito, A.Crisan, Y.Tanaka, “(Cu,C)Ba2Ca3Cu4Ox –(LiF)y
:addition of LiF - an effective way to synthesize overdoped superconductor”, Supercond.
Sci. Technol. 17, 1, (2004)
27.P.Badica, G.Aldica, A.Iyo, I.Bradea, J.Jaklovszky, “Ba/Zr=1:1 freeze-dried and
conventional chloride powders: synthesis of BaZrO3 and phase formation”, Mater. Lett.
58, 250, (2004)
28.V.Mihalache, G.Aldica, S.Popa, F. Lifei, D.Miu, “Effect of Li2CO3 addition on the
Bi1.7Pb0.4Sr1.5Ca2.5Cu3.6Ox superconducting system”, Mater. Lett. 58, (2004)
29.G.Aldica, Gh.Tomozeiu, I.Munteanu, L.Georgescu, M. Chipara, “Physical properties
of pristine and doped polyanilines”, Rom. J. Phys. 49, 71, (2004)
30.V.Sandu, E.Cimpoiasu, Shi Li, M.B.Maple, C.C.Almasan, “Magnetotransport
properties of Y1-xPrxBa2Cu3O7-δ”, Physica C 408-410, 713, (2004)
31.V.Sandu, E.Cimpoiasu, C.C.Almasan, A.P.Paulikas, B.W.Veal, “Charge transport in
spin textured YBa2Cu3O6.25”, J. of Superconductivity, 17, 455, (2004)
32.D.DiGioacchino, P.Tripodi, U.Gambardella, V.Sandu, S.Popa, L.Miu, D.Vinko,
“Third harmonic ac susceptibility measurements in MgB2 bulk: frequency behavior of IL
and 3D glass pinning analysis”, Physica C 408-410, 120, (2004)
14
33.M.Velter-Stefanescu, O.G.Duliu, V.Mihalache, I.Ursu, “Study by magnetically
modulated microwave absorption of Bi1.7Pb0.4Sr1.5Ca2.5Cu3.6Ox/ (LiF)y superconducting
system”, Studia Universitatis Babes-Bolyai, Physica, XLIX, 1, 89-94, (2004)
34.V.Sandu, S.Popa, D.DiGioacchino, P.Tripodi, “Paramagnetism and Superconductivity
in Eu0.7Sm0.3Ba2Cu3O7-δ”, J. Superconductivity, accepted 2004
35.L.Miu, “Influence of the driving force born in magnetization measurements on the
experimentally determined vortex phase diagram of disordered HTS”, Studies of High
Temperature Superconductors (Nova Science Publishers, NY, Ed. A. V. Narlikar), Vol. 48
(in press).
15
Laboratory of Semiconductor Physics
HEAD: Dr. IOANA PINTILIE
Tel.: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES : 19
RESEARCH TEAM: 14
A. GROUP OF SEMICONDUCTOR AND DIELECTRIC THIN FILMS
HEAD: Dr. IOANA PINTILIE
Tel.: (+4021) 493 01 95
Fax: (+4021) 493 02 67
RESEARCH TEAM: 13
Dr. Ioana PINTILIE
Dr. Toni BOTILA1
Dr. Lucian PINTILIE2
Dr. Eugenia PENTIA
Dr. Manuela BUDA
Dr. Bogdan MEREU4
Dr. Alfred GOLDENBLUM6
Dr. Iulian BOERASU
Ion MATEI3
George SARAU5
Viorica DRAGHICI
Marian LISCA
Andreia POPA
senior researcher I
senior researcher I
senior researcher I
1
Retired, employed only for the EU project
Actual address: MPI-Halle, Germany
3
Actual address: MPI-Sttutgart, Germany
4
Actual address: IBM-Zurich, Elvetia
5
Actual address: Research center, Jülich, Germany.
6
Employed only for the EU project INVEST
2
PRESENT RESEARCH INTERESTS :
Photoelectric phenomena and field effect in complex dielectric(ferroelectric)semiconductor structures; photoelectric phenomena in A4B6 , A2B6, oxidic thin films,
ternary semiconductor compounds and semiconductor nano-crystals or nano-structured thin
films; electric properties of MIS structures.
Properties of ferroelectric crystals, ceramics, thin films and graded ferroelectric structures.
16
Trap investigation in semiconducting materials and structures; irradiation induced damages
in Si detectors
Semiconductor detectors and optoelectronic components.
Conduction mechanisms in high-k dielectrics
1. Electric/photoelectric properties of some wide gap semiconductors, including
ferroelectric materials such as PZT
The CERES project 23/2001 was ended. The studies were focused on the
electric/photoelectric properties of some wide gap semiconductors, including ferroelectric
materials such as PZT, in close correlation with their microstructure, especially electrically
active defects (acting as traps). The properties of some complex structures involving
dielectric and photoconductive layers were also investigated. The main results can be
synthesized as follows: 1) the concept of field effect controlled photoconductivity was
demonstrated experimentally and modeled theoretically; 2) deep levels in wide gap
semiconductors influence the photoconductive properties, affecting the life-time of the
photogenerated carriers; 3) the PZT films present both pyroelectric and photoconductive
properties, being a candidate material for light detection in UV (photoconductive effect)
and IR (pyroelectric effect).
2. Use of ferroelectric materials and other IR sensitive materials in gas detection
The CERES project 9/2002 was ended. The studies were focused on the possible use of
ferroelectric materials and of other IR sensitive materials in gas detection, including the
preliminary development of the associated detection techniques. The prototype materials
were single crystal TGS and thin films of PbS. The IR sensitivity of the two materials is
based on different principles, piroelectricity in case of TGS, and photoconductivity in case
of PbS. It was found that the flat sensitivity of the TGS in the IR domain, up to about 10
microns, is an advantage in the case of gas detection because includes the main absorption
lines of the dangerous gases and makes easier the quantitative analysis. The limited domain
of IR sensitivity in the case of PbS (up to 3 microns) is a disadvantage because only some
lines are included. Some tests were performed using CO2 and it was shown that TGS is
sensitive enough to be used for gas detection. Both direct absorption and diffusive
reflection can be used as detection technique.
3. Moisture detection using the Near Infrared Spectroscopy based on PbS detectors
In the frame of the NATO Science for Peace project, ended in October 2004, it was shown
that the PbS detectors are suitable for moisture detection using the Near Infrared
Spectroscopy. Ferroelectric nanostructures and ferroelectric-photoconductor nanocomposite materials were prepared using chemical methods and investigated from the
structural point of view. It was shown that ferroelectric properties are still present on
ferroelectric structures of about 20 nm thickness and 150 nm lateral size.
4. Electrical and photoelectrical characterization of Al/LaAlO3/Si and Al/La2Hf2O7/Si
structures
17
High-k dielectric materials are presently intensive investigated for replacing the silicon
dioxide layers in the next MOS transistor generation. In the frame of the FP5- INVEST
project, ended in October 2004, we performed electrical and photoelectrical
characterization of Al/LaAlO3/Si and Al/La2Hf2O7/Si structures in order to identify the gate
leakage mechanisms. Photoelectrical measurements have shown that the current flow
through the La2Hf2O7 layer deposited on silicon takes place via impurity channels. A space
charge limited current is evidenced, for different insulator thicknesses and temperatures.
The analysis demonstrates that this SCL current in thin insulator films can be explained
only by the presence of impurity channels situated near the Fermi level of the injecting
contact.
5. Study of radiation induced defects in silicon diodes and their influence to the device
performance
In the frame of the RD50-CERN collaboration we continued the study of radiation induced
defects in silicon diodes and their influence to the device performance. The differences in
the changes observed in Neff after 24GeV proton irradiation of Cz and Epi silicon can be
explained by the balance between the formation of two type of defects - a deep acceptor
(the I center) and a shallow donor (the BD complex). While the formation of the I center
depends on the concentration of interstitial oxygen, the BDs are generated in materials with
high concentration of oxygen dimers. The BDs introduction rate in Epi diodes was directly
determined from TSC experiments to be 0.7x10-2 cm-1. By taking into account the donor
removal and the generation of the I center, the change of the Neff at 200 C in Epi diodes,
for an equivalent fluence of 1.84x1014 cm-2, can be explained up to a factor of ~ - 2.5x1012
cm-3 which most likely is due to the negative charge introduced by clusters. In the case of
Cz material similar values for the introduction rate of the negative space charge introduced
by clusters at RT (~1.4x10-2 cm-1) was determined. Another important result of the present
study is the first time direct determination of the TDDs capture cross section for electrons
(σnTDD ~ 2.7x10-12 cm2).
INTERNATIONAL COOPERATIONS :
Projects ended in 2004:
NATO Program-“Science for Peace”, (INOWATE) - SfP-971979, participants: Bilkent
Univ. Turkey, NIMP-Bucharest, Romania, Ioffe Ins., Russia, Iowa State Univ., SUA, Univ.
Glasgow, United Kingdom; Project title: Integrated optoelectronic circuits for infrared
wavelength telecommunication (1998-2003)
EU funded project; Project title: Integration of very high-k dielectrics with silicon CMOS
technology / Extension with newly Associated States (CONTRACT N° IST-2000-28495
INVEST/INVEST-EAST, period 2002-2004)
Ongoing project:
RD50 – CERN “Radiation hard semiconductor devices for very high luminosity colliders”
Other cooperation:
University of Hamburg, Germany (irradiation induced damages in Si detectors)
University do Minho, Portugal (ferroelectric thin films)
18
MPI, Halle, Germany (SEM, high-k dielectrics)
TECHNOLOGIES AND SERVICES :
- trap investigation in semiconducting materials and structures using TSC and OCS
methods
- low temperatures electric and photoelectric measurements
- optical and electrical characterization of visible and IR detectors
PAPERS PUBLISHED OR ACCEPTED FOR PUBLISHING IN 2004:
1. L.Pintilie, I.Boerasu, M.J.M.Gomes, M.Pereira “Properties of Pb(Zr0.92Ti0.08)O3 thin
films deposited by sol-gel”, Thin Solid Films, Volume 458, Issues 1-2, 114-120 (2004)
2. L.Pintilie, I.Boerasu, M.Pereira, M.J.M.Gomes, “Structural and electrical properties of
sol-gel deposited Pb(Zr0.92Ti0.08)O3 thin films doped with Nb”, Materials Science and
Engineering B, Volume 109, Issues 1-3, 174-177 (2004)
3. B.Mereu, G.Sarau, E.Pentia, V.Draghici, M.Lisca, T.Botila, L.Pintilie, “Field-effect
transistor based on nanometric thin CdS films”, Materials Science and Engineering B,
Volume 109, Issues 1-3, 260-263 (2004)
4. B.Mereu, G.Sarau, A.Dimoulas, G.Apostolopoulos, J.C.Hooker, I.Pintilie, T.Botila,
L.Pintilie, M.Alexe “Electrical properties of metal-oxide-silicon structures with LaAlO3
as gate oxide”, Materials Science and Engineering B, Volume 109, Issues 1-3, 94-98
(2004)
5. H.V.Alexandru, C.Berbecaru, F.Stanculescu, L.Pintilie, I.Matei, M.Lisca “Doped TGS
crystals for IR detection and sensors “, Sensors and actuators a: physical, 113 (3), 387-392
(2004)
6. L.Pintilie, M.Pereira, M.J.M.Gomes, I.Boerasu “Pyroelectric current spectroscopy:
example of application on Nb doped Pb(Zr0.92Ti0.08)O3 ceramics for infrared detection”,
Sensors and actuators a: physical, 115 (2-3), 185-190 (2004)
7. E.Pentia , V.Draghici , G.Sarau , B.Mereu , L.Pintilie , F.Sava , M.Popescu ,
“Structural, electrical, and photoelectrical properties of CdxPb1-xS thin films prepared by
chemical bath deposition”, Journal of the Electrochemical Society 151 (11), G729-G733
(2004)
8. I.Boerasu, L.Pintilie, M.J.M.Gomes, M.Pereira, “Growth and properties of Pb
(Zr0.92Ti0.08)O-3 thin films”, Integrated Ferroelectrics 62, 83-87 (2004)
9. D.Menichelli, M.Scaringella, M.Bruzzi, I.Pintilie, E.Fretwurst, “Anomalous current
transients related to defect discharge in irradiated silicon diodes” Physical Review B 70
(19), 195209 (2004)
19
10. D.Menichelli, M.Scaringella, S.Miglio, M.Bruzzi, Z.Li, E.Fretwurst, I.Pintilie,
“Influence of deep levels on space charge density at different temperatures in gammairradiated silicon” Nuclear Instruments & Methods In Physics Research , Section AAccelerators, Spectrometers ,Detectors and Associated Equipment 530 (1-2), 139-145
(2004)
11. G.Lindstroem, E.Fretwurst, G.Kramberger, I.Pintilie, “Toward super radiation
tolerant semiconductor detectors for future elementary particle research”, Journal of
Optoelectronics and Advanced Materials 6 (1), 23-38 (2004)
CONFERENCE PROCEEDINGS:
1. L.Pintilie, M.Lisca, M.Alexe, “Electric and ferroelectric properties of Pb(Zr0.2Ti0.8)O3
thin films deposited by Pulsed Laser Deposition on single crystalline substrates”,
Proceedings 27th International Semiconductor Conference (IEEE Catalog Number
04TH8748; ISBN 0-7803-8499-7), 415-418, (2004)
4 Ph.D. thesis in different phases of elaboration
Ph.D. theses successfully defended:
Bogdan Mereu has got the Ph.D. title at the Politechnica University Bucharest.
B. GROUP OF RESONANT PIEZOELECTRIC STRUCTURES
HEAD: Dr. IRINA MATEESCU
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES : 3
RESEARCH TEAM: 2
Dr. Irina MATEESCU
Drd. Cristina BRAN
Mass-loading effect on characteristics of AT-cut quartz and Y-cut langasite resonators
Vibration mode analysis by X-ray topography in quartz and langasite resonators
Synthesis and characterization of langatate – a new piezoelectric crystal
The comparative study of the mass-loading effects on characteristics of resonant structures
realized on various piezoelectric crystals
Mass-loading effects on electrical characteristics of GaPO4 resonators
20
1.Investigations by X-ray topography of quartz and langasite resonators
A good agreement between the results of the study by X-ray topography of the massloading effects on characteristics of the thickness-shear vibrating resonators (AT-cut quartz
and Y-cut langasite) and the results of the electrical measurements was obtained. The
analysis of the langasite resonators has revealed that the fundamental mode is weakly
trapped, while the overtones are much more confined. X-ray diffracted intensity is
practically unchanged for all electrode thickness and for high overtones. In case of quartz
resonators diffracted intensity has shown an anisotropic dependence on harmonic order and
mass-loading. That indicates a less non-uniform distribution of motion over the electrodes
in Y-cut langasite resonators than in the case of AT-cut quartz resonators. The results
obtained by X-ray topography are in good agreement with harmonic dependence of
motional inductance and quality factor.
The results of the investigations by X-ray topography of the langasite resonators allow us
to conclude that the mass-loading influence on langasite resonator characteristics is smaller
than in the case of quartz resonators.
The results of this study were presented to the 4th European Workshop on Piezoelectric
Materials, Montpellier, France, 21-23 July 2004 and will be published in Journal de
Physique IV.
2.The vibration modes measurements by X-ray topography in SC-cut quartz and Y-cut
unpolished langasite resonators
The results of the investigations by X-ray topography of the Y-cut langasite resonators and
SC-cut quartz resonators allow us to conclude that the mass-loading influence on the
characteristics of the Y-cut langasite resonators and SC-cut quartz resonators is smaller
than in the case of AT-cut quartz resonators.
The results, obtained in cooperation with researchers from University « Pierre et Marie
Curie », Paris and from Sawyer Research Co., USA, were presented to 2004 IEEE
International Ultrasonics, Ferroelectrics and Frequency Control Conference, Montreal,
Canada, 24-27 August 2004 and will be published in Proceedings.
3.Synthesis and preliminary characterization of the langatate crystal
The studies pointed out the behavior of the electrical parameters, of the vibration modes
and frequency-temperature characteristic of langatate resonators. We intend to realize bulk
wave resonators from Y-cut langatate crystal having the same frequency and geometry as
of the AT-cut quartz and Y-cut langasite resonators. A comparative study between
characteristics and mass-loading effect of langatate resonators and those of quartz and
langasite resonators will be performed.
The preliminary study made in this step has shown that langatate has better properties as
those of both crystals mentioned above. The motional inductance of langatate resonators is
smaller than that of AT-cut quartz resonators and Y-cut langasite resonators, quality factor
has maximum values for Y-cut langatate resonators and the inversion point of the parabolic
frequency-temperature characteristic of langatate resonators is situated between 66.9 and
71.4oC on fundamental frequency and harmonics. The Y-cut langasite resonators have the
inversion temperatures between 25 si 81.40C in function of harmonic order.
21
INTERNATIONAL COOPERATIONS
Project title: “New piezoelectric materials for high performance piezoelectric devices
(resonators, sensors, filters) ” Partner: Institute of Microelectronics, National Center for
Scientific Research « Demokritos », Athens, Greece
Project title: ”New piezoelectric crystal growth, investigation of crystal physical
properties and of the influence of external factors on devices characteristics” Partner:
Piezocryst Gesellschaft fur Piezoelektriche Technologien mbH, Graz, Austria
CONFERENCES:
1. I.Mateescu, B. Capelle, J. Detaint, G. Johnson, E. Tsoi, C. Bran, „Investigations by Xray topography of quartz and langasite resonators”, presented at 4th European Workshop
on Piezoelectric Materials, July 2004, Montpellier, France.
2. I.Mateescu, B. Capelle, J. Detaint, G. Johnson, C. Bran, „Vibration modes analysis by
X-ray topography in quartz and langasite resonators”, Proc. of IEEE Int. UFFC 50th
Anniversary Joint Conference, 24-27 August 2004, Montreal, Canada
EDUCATIONAL ACTIVITIES:
1 PhD student (Cristina Bran)
22
NATIONAL INSTITUTE OF MATERIALS PHYSICS * ANNUAL REPORT 2003
Laboratory of Solid State Magnetism
HEAD : Dr. MIHAELA VALEANU
Tel : (+4021) 493 01 95
Fax: (+4021) 493 02 67
RESEARCH TEAM : 21
A. GROUP OF ELECTRONIC PROCESSES VIA NUCLEAR
GAMMA RESONANCE
HEAD : Prof. Dr. GEORGE FILOTI
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES : 8
RESEARCH TEAM : 7
1. Dr. George FILOTI
2. Dr. Victor KUNCSER
3. Dr. Ovidiu CRISAN
4. Dr. Petru PALADE
5. Dr. Daniela PREDOI
6. Gabriel SCHINTEIE
7. Mihai BACANU
senior researcher I
scientific researcher II
technical assistant
1. Nano-particles and nano–phases, including composites, in various matrices
(intermetallics, polymers, oxides and vitreous media). Low dimensionality effects,
including relaxation processes and surface / interface mechanisms
2. Molecular magnetism in metal-organic and co-ordination compounds. The electron
hopping processes, high spin- low spin transition, spin frustration, local structure versus
thermal or irradiation “annealing” behavior etc.
3. Magnetic and electric interactions in materials with various structures
4. Polymers doped with multiple valence transitional metals for integrated optics (storage
and transmission media, real time holography) and gas sensors
23
5. Spin structure at surface and interface. Exchange-bias and exchange spring phenomena
in binary and ternary systems.
6. Computer simulations of electronic and magnetic properties in intermetallics and
nanomaterials.
7. Hydrogen storage in Mg-TM (transitional metal) intermetallics and complex hydrides.
Corelation between microscopic structure and hydrogen storage properties (absorption/desorption kinetics and pressure-composition-isotherm (PCI) behaviour
8. Spin structure and morphology in correlation with GMR effects in nanocomposite thin film.
MAIN SCIENTIFIC RESULTS OBTAINED IN 2004 :
1. Nano-particles and nano–phases, including composites, in various matrices
intermetallics, polymers, oxides and vitreous media
Nano-composites of Fe oxides dispersed in silica matrix were studied by different methods.
The influence of the thermal annealing on the phase composition and grain size of the final
products were analyzed via Mossbauer spectroscopy and microscopic techniques. The kinetics
of crystallization and the growing process of various magnetic nanophases in non-magnetic
metallic matrices were studied in respect to the magnetic properties of the intermetallic
nanocomposite.
2. Molecular magnetism. Metal-organic and coordination compounds: electron hopping, high
spin-low spin transition, spin frustration, local structure, thermal behaviour etc
First specimens of tetranuclear (FeIII, LnIII) clusters assembled by carboxylate ligands and
presenting magnetic order at low temperature (below 80 K) were synthesized and studied
via structural, magnetic and Mossbauer spectroscopic methods.
3. Magnetic and electric interactions in materials with various structures
Local interactions and coordination, valence state and oxygen deficiency were studied in
perovskites and double perovskites in connection with their catalytic and magnetoresitive
properties. Fe-Cu nano-composites obtained by rapid quenching have shown shape induced
magnetic anisotropy.
4. Iron doped polymers: local interactions and optical properties
The refractive index, the film thickness and the surface morphology of metal doped
polymers (from different sources, as salts and/or oxides) were analysed in function on the
preparation conditions and UV exposure characteristics. Doped polymers with improved
properties in respect to the variation of the refractive index vs. the UV exposure (with
influence on both the sensitivity and the diffraction efficiency) have been reported.
24
5. Spin structure at surface and interface. Exchange-bias and exchange spring phenomena
in bi-layer systems
The interfacial spin structure in ferromagnetic/antiferomagnetic and soft magnetic/hard
magnetic systems was analysed by various techniques. New systems presenting exchange
bias phenomena were prepared (e.g. Fe/FeSn2 and Fe/FeGdB). The magnitude of the
exchange bias phenomena in Fe/FeSn2 bi-layers at low temperature was proved to be
dependent on structural characteristics (as Fe and Sn antisite occupation) in the
antiferromagnet. New criteria for the characterization of the interfacial magnetic coupling
strength in soft magnetic/hard magnetic phases were proposed.
Thin magnetic films made of a soft magnetic Fe layer coupled to a hard magnetic FePt one,
separated by a non-magnetic spacer layer like Cu have been synthesised by dc magnetron
sputtering. If exposed to a non-collinear external field, the moments of the system form a
magnetic spiral in the soft magnetic layer. By the integration of a 57Fe probe layer in
different depths within the Fe layer and the use of coherent nuclear resonant scattering of
synchrotron radiation (at the European Synchrotron Radiation Facility (ESRF) Grenoble),
the spin structure and the coupling angle between the moments of successive layers have
been adequately analysed.
6. Simulations of electronic and magnetic properties in intermetallics and nanomaterials
The analysis of the electronic structure performed for LaNiSnH2 and NdNiSnH hydrides
using WIEN-2k band structure calculations code and Gaussian03 molecular calculations
code suggests that the hydrogen bond in these compounds has a donor-acceptor character.
The bond formation between the metal atoms and hydrogen depends on the atomic DOS
energy differences and on the nature of the hybridized orbital. The presence of hydrogen
atoms influences the charge density around Sn atoms via the covalent interaction with Ni
atoms.
Spin structure in ferromagnetic core-shell nanoparticles has been investigated by means of
Monte Carlo simulation with Metropolis algorithm. By using a simple Heisenberg-type
Hamiltonian with exchange, bulk magnetocrystalline and surface anisotropy terms, the
magnetic behavior of a non-magnetic core – ferromagnetic shell bimetallic nanoparticles
has been derived.
7. Hydrogen storage in Mg-TM (transitional metal) intermetallics and complex hydrides
Hydrogen up take absorption/desorption (a/d) and pressure-composition-isotherm
measurements were performed using a Sievert volumetric device operating in automatic
cycling mode . The addition of different oxides to magnesium hydride via ball milling improves
gas-solid reaction kinetics compared with pure magnesium hydride, without influencing the
thermodynamics of hydride formation. Mg-Ni-TM (transitional metal) ribbons obtained by meltspinning exhibit improved hydrogen up take a/d kinetics due to the catalytic effect of TM and
multiphase structure of samples (as results from the multiple plateau pressure PCI behavior).
8. Spin structure and morphology in correlation with GMR effects in a nanocomposite thin film
Thin films of Fe-Cu nanocomposites (Fe clusters in Cu matrix) with various Fe content were
prepared via thermo-ionic vacuum arc. The electric transport properties are studied by four points
methods and the structure, morphology and the magnetic behaviour of the Fe clusters, by X ray
25
diffraction, Atomic Force Microscopy, Transmission Electron Microscopy and temperature
dependent Mossbauer spectroscopy. The aim of the study is to elucidate the microscopic
correlations between the spin structure of the nanoparticle system and the magnetotransport
properties.
INTERNATIONAL COOPERATION & PROJECTS:
1. NATO- Science for Peace Programme- Collaborative Linkage Grant: “Novel magnetic
nanostructures for sensor fabrication” (2004 –2006)
University of Maine and University of Salonic.
2. University of Padova, Italy (via Intergovernmental Agreement Italy - Romania)
Project title: Chemical bonds and structure in metal- organic, coordination compounds
and oxides (2001-2004)
3. University of Padova, Italy (via Intergovernmental Agreement Italy - Romania)
Project title: Hyperfine and magnetic interactions in inter-metalli compounds with complex
structures (2001-2004)
4. University of Maine, Le Mans, France:
Project Title “Nanosystems and their applications: the role of the local structures and
interactions “, Octombrie 2003- Decembrie 2008
5. Bilateral agreement with Institute of Chemistry of Moldovian Academy, Moldova
Project title: “Preparation and characterization of new coordination compounds with
transition metals (2000-2005)”
6. Bilateral co-operation, via CNRS-Romanian Academy agreement with University du
Maine, Le Mans (CNRS), France
Project title: “Conception de nouveaux materiaux a fort effet de surface” (2004- 2005)
7. Bilateral agreement with Aristotle University of Thessaloniki, Greece
Project title: “Structure and interactions in new amorphous and disordered materials”
(2002-2004)
8. Bilateral agreement with University of Duisburg, Germany
Project title: Local structure and magnetic interactions in composite materials with
surface properties (2002-2006)
9. Bilateral cooperation agreement with Rostock University, Germany, ( involving two
laboratories : “Solid State Magnetism” and “Structure and Dynamics of Solids” )
Project title: “Synthesis and characterization of nanostructured materials with advanced
functionalities” (2004- 2008)
1.V.Kuncser, W.Keune, B.Sahoo, E.Duman, M.Acet, F.Radu, M.Valeanu, O.Crisan,
G.Filoti "Magnetic interaction and spin configuration in FeRh and Fe/FeRh systems",
Journal of Magn and Magn. Mat. 272-276, 348-351, (2004)
2.V.Kuncser, M.Valeanu, F.Lifei, D.Predoi, P.Palade, G.Schinteie, O.Crisan, G.Filoti,
“Magnetic interactions and spin structure in composite Fe/Nd2Fe14B systems”, Journal of
Magn and Magn. Mat. 272-276, 797-799, (2004)
26
3.C.Turta, D.Prodius, V.Meriacre, S.Shova, M.Gdaniec, Y.A.Smirnov, V.Kuncser,
G.Filoti, A.Caneschi, L.Sorace, “The first specimen of tetranuclear (FeIII,LnIII) clusters
assembled by carboxylate ligands:synthesis, structure, Mossbauer spectra and magnetic
properties of [Fe3EuO2(CCl3COO)8H2O(THF)3]THF”, Inorganic Chem. Communications
7 576-579, (2004)
4.W.A.Macedo, B.Sahoo, V.Kuncser, J.Eisenmenger, I.Felner, J.Nogues, K.Liu,
W.Keune, I.K.Schuller, “Changes in ferromagnetic spin structure induced by exchange
bias in Fe/MnF2 films”, Phys. Rev. B 70, 224414/1-224414/5, (2004)
5.D.Predoi, V.Kuncser, M.Zaharescu, W.Keune, B.Sahoo, M.Valeanu, M.Crisan,
M.Raileanu, A.Jitianu, G.Filoti, “Structural and magnetic properties of iron species/SiO2
nanocomposites obtained by sol-gel methods”, Phys.Stat.Sol. (c) 1-12 3507-3510, (2004)
6.V.Kuncser, M.Valeanu, F.Lifei, A.Jianu, W.Kappel, G.Filoti, “Local magnetic
interactions in Fe/RE2Fe14B” nanocomposite systems”, Phys.Stat.Sol. (c) 1-12, 3503-3506,
(2004)
7.F.Stromberg, V.Kuncser, K.Westerholt, W.Keune, “Interfacial spin structure in
epitaxial Fe/FeSn2 bilayers with exchange bias”, Phys.Stat.Sol. (c) 1-12 3754-3759, (2004)
8.W.Kappel, M.M.Codecu, I.Pasuk, E.Patroi, V.Kuncser, M.Valeanu, D.Predoi, G.Filoti,
“FexCu1-x alloys for permanent magnets”, J.Opt.Adv.Mat. 6 3, 973-978, (2004)
9.D.Predoi, V.Kuncser, G.Filoti, “Magnetic behaviour of maghemite nanoparticles
studied by Mossbauer spectroscopy” Rom. Rep. in Physics 56-3, 421-427, (2004)
10.C.Valsangiacom, M.Sima, D.Predoi, C.Plapcianu, C.Kuncser, G.Schinteie,
M.Bulinski, “A microscopic analyze of the conduction mechanism of iron doped
polyaniline under the UV exposure” Rom.Phys.Reports, 3-55, (2004)
11.M.Raileanu, M.Crisan, C.Petrache, D.Crisan, D.Predoi, M.Zaharescu, “Nanocompozite
sol-gel pe baza de oxizi de Fe in matrici de silice” Rev. Rom. de Materiale (rom) XXXIV,
3, 189-195, (2004)
12.R.Larde, J.M. Le Breton, F.Richomme, J.Teillet, A.Hauet, A.Maignan, O.Crisan,
“Influence of the SmCo5 hard magnetic phase on the magnetoresistive properties of Cu-Fe
ribbons” J.Phys.-Condens. Mat., 16-41, 7477-7492, (2004)
13.M.Bulinski,
V.Kuncser,
C.Plapcianu,
S.Krautwald,
H.Franke,
P.Rotaru,
G.Filoti,“Optical and electronic properties of polyvinyl alcohol doped with pairs of mixed
valence metal ions”, J.Phys.D:Applied Phys. 37, 2437-2441, (2004)
14.O.Crisan, M.Angelakeris, E.Papaioannou, A.D.Crisan, N.K.Flevaris, N.Vouroutzis,
E.Pavlidou, I.Kostic, N.Sobal, M.Giersig, “Magnetic nanostructures obtained by colloidal
crystallization onto patterned substrates”, J.Magn. Magn. Mater. 272-276, e1285- e1287,
(2004)
27
15.O.Crisan, M.Angelakeris, M.Noguès, E.Papaioannou, N.K.Flevaris, Ph.Komninou,
Th.Kehagias, N.Sobal, M.Giersig, “Correlation of structure and magnetism of Ag/Co
nanoparticle arrays”, J.Magn.Magn.Mater. 272-276, e1253-e1254, (2004)
16.O.Crisan, J.M.Le Breton, A.D.Crisan, F.Machizaud, M.Noguès, “Influence of Gd
addition on the magnetism and structure of Finemet-type nanocrystalline alloys”, J. Magn.
Magn. Mater. 272-276, e1396-e1397, (2004)
17.O.Crisan, J.M.Greneche, Y.Labaye, L.Berger, A.D.Crisan, M.Angelakeris, J.M. Le
Breton, N.K.Flevaris, “Magnetic properties of nanostructured materials: Monte Carlo
simulation and experimental approach for nanocrystalline alloys and core-shell
nanoparticles “ in : M. Miglierini, P. Svec and B. Idzikowski, editors : Properties and
Applications of Nanocrystalline Alloys Prepared from Amorphous Precursors , NATO
Science Series II, Vol. 184, p. 253-266, Kluwer Academic Publishers, Dordrecht, (2004 )
18.O.Crisan, E.E.Tornau, V.Petrauskas, M.Angelakeris, “Monte Carlo simulation study
of magnetic behaviour of core-shell bimetallic nanoparticles“, Phys.Stat. Sol.(c) 1 (12)
3760-3763, (2004)
19.V.Petrauskas, O.Crisan, E.E.Tornau, ”Effect of surface anisotropy on magnetization of
core-shell bimetallic nanoparticles”, Acta Physica Polonica A in print, (2004)
20.V.Kuncser, R.Nicula, U.Ponkratz, A.Jianu, M.Stir, E.Burkel, G.Filoti, “Structural
phase transitioninduced in Fe50Rh50 alloys by high pressure” Journal. of Alloys and Comp.,
in press, Corrected Proof available on line Dec. (2004)
21.P.Palade, G.Principi, T.Spataru, P.Blaha, K.Schwarz, V.Kuncser, S. Lo Russo, S.Dal
Toe, V.A.Yartys, “Mossbauer study of LaNiSn and NdNiSn compounds and their
deuterides”, in print, J. Radioanal. Nucl. Chem.
22.T.Spataru, P.Palade, G.Principi, P.Blaha, K.Schwarz, V.Kuncser, S. Lo Russo, S.Dal
Toé, V.A.Yartys, “The nature of the hydrogen bond in the LaNiSnH2 and NdNiSnH
hydrides”, accepted for publication in J. Chem. Phys.
23.M.Raileanu, M.Crisan, C.Petrache, D.Crisan, A.Jitianu, M.Zaharescu, D.Predoi,
V.Kuncser, G.Filoti, „Sol-gel FexOy-SiO2 nanocomposites” in print J.Rom. Phys.
24.C.Piquer, J.Rubín, J.Bartolomé, V.Kuncser, G. Filoti, “A 57Fe Mössbauer spectral
study of the RFe11.5Ta0.5 compounds”, in print in Proceedings of ISIAME Conference,
Madrid, October 2004
CONFERENCES :
nanocomposites obtained by sol-gel methods”, Second Seeheim Conference on
Magnetism, Seeheim, Germany, 27 June-1 July 2004, Germany
28
interactions in Fe/RE2Fe14B” nanocomposite systems”, Second Seeheim Conference on
3.F.Stromberg, V.Kuncser, K.Westerholt, W.Keune, “Interfacial spin structure in
epitaxial Fe/FeSn2 bilayers with exchange bias” Second Seeheim Conference on
4.G.Principi, P.Palade, A.Maddalena, S.Sartori, T.Spataru, S Lo Russo, S. Dal Toe,
“Hydrogen storage in nanosized magnesium-based alloys”, VII Italian Meeting on
Nanophase Materials, Roma, Italy, 16-17 Sept. 2004
5. T.Spataru, P.Palade, P.Blaha, K.Schwarz, V.Kuncser, S. Lo Russo, S. Dal Toé, V.A.
Yartys, G.Principi, “The nature of the hydrogen bond in the LaNiSnH2 and NdNiSnH
hydrides”, “EWS’04: Chemical applications of Mossbauer Spectroscopy”, Budapest,
Hungary, 10-13 Oct. 2004
6. C.Piquer, J.Rubín, J.Bartolomé, V.Kuncser, G. Filoti, “ A 57Fe Mössbauer spectral
study of the RFe11.5Ta0.5 compounds”, ISIAME Conference, Madrid, October 2004
7. O.Crisan, “Ag/Co nanoparticle system: an overview”, invited lecture, presented at 7th
Workshop on Correlation of Structure and Magnetism in Novel Nanoscale Magnetic
Particles, Bonn, Germany, february 2004
8. V.Petrauskas, O.Crisan, E.E.Tornau, ”Effect of surface anisotropy on magnetization of
core-shell bimetallic nanoparticles”, presented at the 12th International Symposium on
Ultrafast Phenomena in Semiconductors, UFPS 12, Vilnius, Lithuania, august 2004
9. O.Crisan, E.E.Tornau, V.Petrauskas, M.Angelakeris, “Monte Carlo simulation study of
magnetic behaviour of core-shell bimetallic nanoparticles“, presented at the 2nd Seeheim
Conference on Magnetism, SCM 2, Seeheim, Germany, june 2004
GRANTS :
“Physical chemicals properties at interface in nanometric composites”, Dr. Daniela
Predoi grant awarded by the Romanian Academy
“Interface electronic mechanisms in metallic composites”, Prof. Dr. George Filoti, grant
awarded by Romanian Academy
- Ph.D. promoter - Dr.G.Filoti: 4 Ph.D. theses in different phases of elaboration
Dr. George Filoti is Professor at the “Condensed Matter” Chair of Faculty of Physics,
University of Bucharest
29
FOREIGN GUESTS:
Dr. Jean Marc Greneche, Directeur de Recherche, CNRS-University of Maine, Le Mans,
France
Dr. Nirina Randrianantoandro, Maitre de Conference, University of Maine, Le Mans,
France
B. GROUP OF RARE-EARTH MAGNETIC COMPOUNDS
HEAD : Dr. MIHAELA VALEANU
Tel : (+4021) 493 01 95
Fax: (+4021) 493 02 67
RESEARCH TEAM : 10
Dr. Mihaela VALEANU
Dr. Dorin Petru LAZAR
Dr. Mircea MORARIU
Dr. Neculai PLUGARU
Dr. Andrei GALATEANU
Dr. Marilena TOMUT
Mihaela SOFRONIE
Felicia LIFEI
Bogdan POPESCU
Alina CRISAN
Tatiana NUTU
Gilda GAVRILUT
Gheorghe LAZAR
senior researcher I
senior researcher I
senior researcher I
senior researcher I
technical assistant
technical assistant
technical assistant
PRESENT RESEARCH INTERESTS :
Magnetic phenomena in 3D nanosized systems
Intermetallics, crystalline and amorphous alloys. Kinetics of crystallization; structural relaxation.
Rare earth-iron nanocomposite magnetic materials
Magnetic contributions in iron – rare earth intermetallic compounds
Magnetoresistance effects in perovskites
5f electron magnetism in U based intermetallic compounds
Superconductivity and magnetism interplay in heavy fermion compounds
30
1. Magnetic phenomena in 3D nanosized systems
- The magnetic hardening induced by the crystallization processes on nanocomposites with
nominal compositions Nd10-xFe86+xB4 (0 ≤ x ≤ 3) was studied. Magnetic measurements were
performed on samples after different annealing treatments in order to find the optimal
conditions for the best inter-phases exchange coupling. The Fe spin configurations in both
the soft- and hard- magnetic phases of nanocomposite Fe/RE2Fe14B exchange-spring
ribbons in demagnetized and remanence states have been analyzed by Mössbauer
spectroscopy. A new criterion for evaluating the inter-phase exchange-coupling strength
was proposed.
- Magnetic nanocomposite based on Fe-Pt hard magnetic phase, with 3 different
compositions - Fe68Pt21Nb2B9, Fe65Pt25Nb2B8 and Fe68Pt13Nb2B17 - have been synthesized by
the rapid solidification technique. The crystallization kinetics for the ribbons has been
modeled, using DSC scans taken at different heating rates, (5, 10, 15 and 20 K/min.).
Structural studies performed by X-ray diffraction of the as-cast and DSC annealed ribbons
were corroborated with Mossbauer spectroscopy results, in order to obtain the phase
composition of the samples. (in collaboration with Physical Department of Rostock
University)
2. Magnetic and crystalline properties in iron or nickel based rare-earth intermetallics
- The effects of V substitution in Pr2Fe17-xVx and PrFe12-xVx compounds were investigated
by X-ray diffraction and Mössbauer spectroscopy. Rietveld analysis of X-ray diffraction
data has been used to determine the crystal lattice distortions and the preferential
substitution of V atoms on the 6c crystallographic site in Pr2Fe17-xVx and on the 8i site in
PrFe12-xVx. The hyperfine fields decrease significantly with increasing V content, as also
expected from the Wigner-Seitz cell volume decrease. The evolution of the Mössbauer
parameters as function of V content points to increasing Debye temperatures with V
content as an effect of electron charge hybridization and strong modification of the
exchange integrals for the sites having larger amounts of surrounding V atoms.
- For Nd3Co13-xNixB2 series of compounds, the local contributions to 3d anisotropy, the
exchange and crystal field at the rare earth site and the magnetic structures were
investigated. A complex AF structure in Nd3Ni13B2 and the occurence of several field and
temperature induced magnetic phase transitions have been evidenced. The magnetic phase
diagram of the Nd3(Co,Ni)13B2 system was derived. ( in collaboration with University of
Zaragoza, Spain)
3. Magnetoresistance Effects in Perovskites
Polycrystalline samples of Sr2FeMoO6, Sr2 (FeCo)MoO6 and Sr2Fe(MoTa)O6 were prepared
by standard solid state reaction. For the un-substituted sample, XRD measurements reveal
a low antisite defect concentration of around 3% and a value for the saturation
magnetization of 3.5µB/f.u. Paramagnetic measurements suggest a percentage of 60%Fe2+
ions while 30% of the Mo ions are in the +5 valence state.
31
4. High temperature 5f electron magnetism in U based intermetallic compounds
A systematic study of the magnetic behavior for typical U based intermetalic compounds was
performed on high quality single crystals. In most of the investigated compounds a cross-over
from a low temperature delocalized character to a high temperature localized character was
observed for the 5f electrons. This behavior is found to be characteristic for heavy fermions
systems like UPt3 or UPd2Al3, or for ferromagnetic superconductors like UGe2 and UIr, spin
fluctuation compounds as UB4, but also for antiferromagnets like USb2 or UNiSb2. To asses the
extend of this behavior in U compounds typical itinerant systems like UGa3 and those from the
related UMGa5 series (M = Ni, Pd, Ir) were also investigated. (in collaboration with Advanced
Science Research Center, Tokai, Japan)
5. Exotic superconductivity and magnetism in the heavy fermions compound CePt3Si
Magnetic and thermodynamic investigations as well as neutron scattering experiments
were carried out on both polycrystalline and single crystal samples and the magnetic
structure was clarified. The AFM structure of two interleaved ferromagnetic sublattices of
local Ce 4f moments has inversion symmetry under simultaneous space–time reversal.
However, hybridization with Pt and Si breaks this degeneracy and a combination of these
two competing effects may be relevant to an understanding of the simultaneous occurrence
of superconductivity and AFM order. The observed magnetic moment 0.16 µB/Ce is
strongly reduced from the Curie–Weiss effective moment 2.54 µB/Ce. Clear crystal field
excitations at 1 and 24 meV were observed and the magnetic susceptibility could be well
explained in a level scheme assuming a Γ7 ground state and a Γ 6 and Γ 7 first and second
excited states, respectively. (in collaboration with Advanced Science Research Center,
Tokai, Japan)
PROMOTED INTERNATIONAL COOPERATION & PROJECTS:
- Bilateral agreement with Institut fur Oberflachen und Dunnschichttechnik
(IfOD)
Hochschule Wiesmar Germany
Project title: “Structural and magnetoresistive effect investigations in double perovskites”
- Bilateral agreement with BarIlan University, Department of Chemistry, Ramat Gun,
Israel.
Project title: ” Nanomaterials and nanocomposites for special application”.
PAPERS PUBLISHED OR ACCEPTED FOR PUBLISHING IN 2004 :
1.A.Jianu, M.Valeanu, D.P.Lazar, F.Lifei, C.Bunescu, V.Pop, “Effects of Zr and Ti
substitutions on the crystallization processes and magnetic properties of Fe3B/Nd2Fe14B
nanocomposite magnetic system”, J.of Mag.& Mag.Mat. 272-276, 1493-1495, (2004)
2.A.Jianu, M.Valeanu, D.P.Lazar, F.Lifei, M.Tomut, V.Pop, S.Alexandru,
“Crystallization processes of Fe3B/Nd2Fe14B nanocomposite magnetic system”, Rom
Rep.Phys 56, 435-439, (2004 )
32
3.I.Lupsa, M.Valeanu, “Magnetic behaviour of U(NixSi1-x)2 system”, Rom.Rep.Phys. 56,
429-434, (2004 )
4.V.Kuncser, M.Valeanu, F.Lifei, D.Predoi, P.Palade, G.Schinteie, O.Crisan, G.Filoti,
“Magnetic interactions and spin structure in nanocomposite Fe/Nd2FE14B systems“,J.of
Mag.& Mag.Mat. 272-276, 797-799, (2004 )
5.V.Kuncser, W.Keune, B.Sahoo, E.Duman, M.Acet, F.Radu, M.Valeanu, O.Crisan,
G.Filoti “Magnetic interactions and spin configuration in FeRh and Fe/FeRh systems”J.of
Mag.& Mag.Mat. 272-276, 348-350, (2004 )
6.W.Kappel, M.M.Codescu, I.Pasuk, E.Patroi, V.Kuncser, M.Valeanu, D.Predoi, G.Filoti,
“FexCu1-x alloys for permanent magnets” Journal of Optoelectronics and Adv.Mat., 6(3),
973-978, (2004 )
7.E.Burzo, R.Tetean, L.Ghioncel, M.Valeanu „Magnetic properties of GdxY1-xCo3NiB
compounds” Phys.Stat Solidi.( c ) 1, 3207-3210, (2004)
8.V.Kuncser, M.Valeanu, F.Lifei, A.Jianu, W.Kappel, G.Filoti “Local magnetic
Interactions in Fe/RE2Fe14B nanocomposite systems” Phys.Stat Solidi.( c ) 1, 3503-3506,
(2004)
M.Raileanu, A.Jitianu, G.Filoti, „Structural and magnetic properties of iron species/SiO2
nanocomposites obtained by sol-gel methods” Phys.Stat.Sol.(c ). 1, 3507-3510, (2004)
10.M.Sorescu, L.Diamandescu, M.Valeanu, A.Jianu, “Effects of cobalt substitutions in
spring magnets” J.of Materials Science 39, 7387-7389, (2004)
11.J.Stankiewicz, J.Bartolomé, N.Plugaru, “Electrical resistivity of RFe11.5Ta0.5 and
RFe11.3W0.7 Alloys” J.Phys.: Condens.Matter 16, 6485-6492, (2004)
12.F.Bartolomé, J.Herrero-Albillos, L.M.García, A.T.Young, T.Funk, N.Plugaru,
E.Arenholz, “Orbital moment at the Curie temperature in ErCo2” J.Magn.Magn.Mat., 272276, 319-320, (2004)
13.V.Mihalache, G.Aldica, S.Popa, F.Lifei, D.Miu “Effect of Li2CO3 addition on the
Bi1.7Pb0.4Sr1.5Ca2.5Cu3.6Ox superconducting system”, Materials Letters 58, 3040-3044,
(2004)
14.T.Ueda, H.Shishido, S.Hashimoto, T.Okubo, M.Yamada, Y.Inada, R.Settai, H.Harima,
A.Galatanu, E.Yamamoto, N.Nakamura, K.Sugiyama, T.Takeuchi, K.Kindo, T.Namiki,
Y.Aoki, H.Sato, Y.Onuki, "Electronic, magnetic and superconducting properties of quasitwo dimensional compounds Ce2RhIn8 and La2RhIn8", J.Phys.Soc.Japan 73, 649-655,
(2004)
33
15.H.Shishido, N.Nakamura, T.Ueda, R.Asai, A.Galatanu, E.Yamamoto, Y.Haga,
T.Takeuchi, Y.Narumi, T.C.Kobayashi, K.Kindo, K.Sugiyama, T.Namiki, Y.Aoki, H.Sato,
Y.Onuki, "Electrical, thermal and magnetic properties of CeNiIn4", J.Phys.Soc.Japan 73,
664-668, (2004)
16.A.Galatanu, Y.Haga, E.Yamamoto, T.D.Matsuda, S.Ikeda, Y.Onuki, "High
temperature magnetic properties of UIr single crystals", J.Phys.Soc.Japan 73, 766-767,
(2004)
17.N.Metoki, K.Kaneko, T.D.Matsuda, A.Galatanu, T.Takeuchi, S.Hashimoto, T.Ueda,
R.Settai, Y.Onuki, N.Bernhoeft, "Magnetic structure and the crystal field excitation in
heavy-fermion antiferromagnetic superconductor CePt3Si", J.Phys.:Cond.Matter 16, L207L212, (2004)
18.T.Takeuchi, A.Thamizhavel, T.Okubo, M.Yamada, Y.Inada, A.Galatanu, E.Yamamoto
and Y.Onuki, "Thermal expansion and magnetostriction in CeRh3B2", J.Magn.Magn.Matt.
272-276, E17-E18, (2004)
19.S.Ikeda, T.D.Matsuda, A.Galatanu, E.Yamamoto, Y.Haga, Y.Onuki, "Single crystal
growth and magnetic property of UNiSb2", J.Magn.Magn.Matt. 272-276, 62-63, (2004)
20.M.Yamada, Y.Obiraki, T.Okubo, T.Shiromoto, Y.Kida, M.Shiimoto, H.Kohara,
T.Yamamoto, D.Honda, A.Galatanu, Y.Haga, T.Takeuchi, K.Sugiyama, R.Settai,
K.Kindo, S.K.Dhar, H.Harima, Y.Onuki, "Magnetic and fermi surface properties in
PrRh3B2", J.Phys.Soc.Japan 73, 2266-2275, (2004)
21.Y.Okuda, T.Takeuchi, T.Yamamoto, D.Honda, H.Shishido, A.Galatanu, T.D.Matsuda,
Y.Haga, K.Kindo, K.Sugiyama, R.Settai, Y.Onuki, "Magnetic and fermi surface properties
of an antiferromagnet Ce3Sn7", J.Phys.Soc.Japan 73, 2276-2282, (2004)
22.T.D.Matsuda, A.Galatanu, Y.Haga, S.Ikeda, E.Yamamoto, M.Hedo, Y.Uwatoko,
T.Takeuchi, K.Sugiyama, K.Kindo, R.Settai, Y.Onuki, "Small saturation moment due to
the crystalline electric field effect for Th site symmetry in the ferromagnet UFe4P12",
J.Phys.Soc.Japan 73, 2533-2538, (2004)
23.O.Crisan, M.Angelakeris, E.Papaioannou, A.D.Crisan, N.K.Flevaris, N.Vouroutzis,
E.Pavlidou, I.Kostic, N.Sobal, M.Giersig, “Magnetic nanostructures obtained by colloidal
crystallization onto patterned substrates”, J.Magn.Magn.Mater. 272-276 , e1285- e1287,
(2004)
24.O.Crisan, J.M.Le Breton, A.D.Crisan, F.Machizaud, M.Noguès, “Influence of Gd
addition on the magnetism and structure of Finemet-type nanocrystalline alloys”,
J.Magn.Magn.Mater.272-276, e1396-e1397, (2004)
25.O.Crisan, J.M.Greneche, Y.Labaye, L.Berger, A.D.Crisan, M.Angelakeris, J.M.Le
Breton, N.K.Flevaris, “ Magnetic properties of nanostructured materials: Monte Carlo
simulation and experimental approach for nanocrystalline alloys and core-shell
nanoparticles“ in : M.Miglierini, P.Svec and B.Idzikowski, editors: Properties and
34
Applications of Nanocrystalline Alloys Prepared from Amorphous Precursors , NATO
Science Series II, Vol.184, p.253-266, Kluwer Academic Publishers, Dordrecht, (2004)
26.O.Crisan, J.M.Le Breton, F.Machizaud, M.Noguès, A.D.Crisan, J.Teillet, G.Filoti,
“Crystallization products and phase structure of nanocrystalline soft magnetic ribbons",
submitted to J.Phys.: Condens.Matter, (2004)
27.D.P.Lazar, N.Plugaru, M.Valeanu, A.Galatanu, R.M.Leonovici, A.Dafinei, L.Ion,
„Magnetic and Mössbauer spectroscopic study of R3Fe29-xMox (R = Y, Nd, Sm, Gd, Tb, and
Dy”, J.Alloys and Compounds, (in proof)
28.D.P.Lazar, V.Kuncser, M.Valeanu, G.Filoti, J.Bartolomé, J.Rubín, N.Plugaru
“Mössbauer spectral study of RFe11.3W0.7 compounds (R = Dy, Ho, Er, and Lu)”, J.Physics:
Condensed Matter ( in proof).
29.V.Kuncser, M.Valeanu, F.Lifei, A.Jianu, D.Predoi M.Codescu, W.Kappel, G.Filoti
“Micro-structure and magnetic properties of Fe-Cu nanocomposites as potential
candidates for R E-Free permanent magnets” J.of Alloys and Commpounds (in proof)
30.F.Lifei, C.P.Cristescu, A.Toma “YAG-Nd laser irradiation effects of phase structure
modification in partially crystallized Fe78B13Si9”.Analele– UPB ( accepted)
CONFERENCES :
1. N.Plugaru, C.Piquer, F.Grandjean, J.Rubín, J.Bartolomé “A Magnetic and 57Fe
Mössbauer spectral study of the Hf1-xRxFe6Ge6 (R=Gd and Dy) compounds” Int.
Symposium on the Industrial Applications of Mössbauer Effect, ISIAME 2004, Eds. M.
Gracia, J.F. Marco and F. Plazaola, Madrid, Spain, Oct. 4-8, 2004, Proceed. Book, in press.
2. D.Predoi, V.Kuncser, M.Zaharescu, W.Keune, B.Sahoo, M.Valeanu, M.Crisan,
nanocomposites obtained by sol-gel methods”, Second Seeheim Conference on
interactions in Fe/RE2Fe14B” nanocomposite systems”, Second Seeheim Conference on
4.F.Lifei, M.Sofronie, B.Popescu, G.Scintei, V.Kuncser, A.Jianu, M.Valeanu, G.Filoti
“Magnetic interactions in Nd2Fe14B/α-Fe nanocomposites” One-day Seminar "Magnetic
NanoMaterials - Preparation, Characterization & Applications" 27 Septembrie 2004 – Iasi
5.A.Ioachim, M.I.Toacsan, M.G.Banciu, L.Nedelcu, D.Ghetu, M.Feder, C.Plapceanu,
F.Lifei “Synthesis and dielectric properties of Ba(Zn1/3Ta2/3)O3 ceramics”– a IX-a sesiune
de comunicari stiintifice “STIINTA SI INVATAMANTUL FUNDAMENTE ALE
SECOLULUI AL XXI-lea”, SIBIU, 25-26 Noiembrie 2004
35
6.T.Ueda, R.Asai, H.Shishido, A.Galatanu, Y.Haga, T.Takeuchi, R.Settai, Y.Onuki,
"Magnetism and resistivity under pressure in single-crystal CeRhGe", 59th Annual Meeting
of JPS, March 27-30 2004, Fukuoka, Japan
7.Y.Okuda, H.Kohara, T.Yamamoto, D.Honda, H.Shishido, T.Shiromoto, M.Nakagawa,
T.Takeuchi, A.Galatanu, Y.Haga, K.Kindo, K.Sugiyama, R.Settai, Y.Onuki "Magnetism
and dHvA effect in Ce2Sn5 and Ce3Sn7", 59th Annual Meeting of JPS, March 27-30 2004,
Fukuoka, Japan
8.S.Ikeda, T.D.Matsuda, Y.Haga, A.Galatanu, Y.Onuki, "Single crystal growth and
physical properties of UIr3B2", 59th Annual Meeting of JPS, March 27-30 2004, Fukuoka,
Japan
9.A.Galatanu, Y.Haga, E.Yamamoto, T.D.Matsuda, S.Ikeda, D.Aoki, Y.Onuki "High
temperature magnetic behavior of U based intermetallic compounds", presented at 59th
Annual Meeting of JPS, March 27-30 2004, Fukuoka, Japan
10.K.Sugiyama, M.Yamamoto, D.Honda, T.Takeuchi, T.D.Matsuda, A.Galatanu, Y.Haga,
Y.Narumi, K.Kindo, Y.Onuki "High field magnetization of UFe4P12", 59th Annual Meeting
of JPS, March 27-30 2004, Fukuoka, Japan
11.Y.Okuda, T.Yamamoto, D.Honda, H.Shishido, A.Galatanu, Y.Haga, T.Matsuda,
T.Takeuchi, K.Kindo, K.Sugiyama, R.Settai, Y.Onuki "CEF-scheme of a semimetal
Ce3Sn7", SCES'04, July 26-30 2004, Karlsruhe, Germany
12.N.Metoki, K.Kaneko, T.D.Matsuda, A.Galatanu, T.Takeuchi, S.Hashimoto, T.Ueda,
R.Settai, Y.Onuki, N.Bernhoeft, "Magnetic structure and CEF excitation in heavy fermion
superconductor EF-scheme of a semimetal CePt3Si", SCES'04, July 26-30 2004, Karlsruhe,
Germany
13.T.Ueda, D.Honda, T.Takeuchi, A.Galatanu, Y.Haga, K.Sugiyama, K.Kindo, R.Settai,
Y.Onuki, "Presure-induced huge resistivity peak in CeRhGe", SCES'04, July 26-30 2004,
Karlsruhe, Germany
14.Y.Haga, T.D.Matsuda, S.Ikeda, A.Galatanu, T.Matsumoto, T.Sugimoto, T.Tada,
S.Noguchi, Y.Onuki, "Single crystal growth and magnetic properties of a new ternary
uranium compound U3Ni5Al19", SCES'04, July 26-30 2004, Karlsruhe, Germany
15.S.Ikeda, M.Nakashima, S.Kirita, T.D.Matsuda, A.Galatanu, Y.Haga, E.Yamamoto,
K.Kaneko, N.Metoki, M.Hedo, Y.Uwatoko, Y.Onuki, "Electrical and magnetic properties
of UNiGa5, UPdGa5 and UPtGa5", SCES'04, July 26-30 2004, Karlsruhe, Germany
16.T.D.Matsuda, Y.Haga, S.Ikeda, A.Galatanu, H.Shishido, M.Yamada, J.Yamaura,
T.Matsumoto, T.Tada, S.Noguchi, K.Kuwahara, K.Iwasa, M.Kohgi, M.Hedo, Y.Uwatoko,
R.Settai, Y.Onuki "Anisotropic magnetism and Fermi surface properties of a ferromagnet
UCu2Si2", SCES'04, July 26-30 2004, Karlsruhe, Germany
36
Dr. N Plugaru is Assistant Professor at the University of Zaragoza, Spain, teaching
"Electromagnetic Fields and Waves" and "Fundamentals of Materials Science", graduate
level.
C. GROUP OF NON-EQUILIBRIUM MATERIALS AND PROCESSING
HEAD: Dr. ADRIAN JIANU
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 4
RESEARCH TEAM: 2
Dr. Adrian JIANU
Dr. Mihaela Carmen BUNESCU
Marcela TRUPINA
Andrei STOICA
technical assistant
technical assistant
1. Material processing: rapid solidification of metallic melts, mechanical alloying,
reactive synthesis, field activated sintering, physical vapours deposition.
2. Materials under investigation: Synthesis of new materials by tailoring of structure at
the nanoscale scale: shape memory alloys, hard magnetic alloys and composites, carbonbased nanostructures, materials for energy storage, materials for hydrogen storage,
functional gradient materials.
3. Materials under “hostile” environment (high-Temperature/Mechanical loading/fast
Neutron irradiation): SiC-based composites, ODS-steels, brazing alloys
1. Microstructure analysis of carbon nanotubes coatings
Objectives: to establish a cheap and reliable method to produce carbon nanotubes coatings
on large surfaces, with possibility to scale up to larger out-put, aiming at gas sensor
applications. Results: (i) a high diversity of carbon products (amorphous carbon, graphite
plates, multi wall carbon nanotubes, onion-like graphene), depending on the metal catalyst;
(ii) uniform coatings for certain combination of working parameters (temperature, catalyst,
etc). (Research project at Hochschule Wismar)
37
2. Microstructural investigation of nano-catalyst particles
Objectives: (i) electroless deposition of metallic catalysts on carbon nanotubes; (ii) to
improve the power density of the fuel cell. Results: (i) new electrode material for fuel cells;
(ii) cell performances were improved as compared with the standard catalysts. (Research
project at Hochschule Wismar)
3. Carbon nanostructures produced by CCVD with induction heating
The catalytic chemical vapor deposition (CCVD) method in which the outer furnace is
replaced by the high frequency induction heating (IH) has been used for synthesis of carbon
nanostructures. Using different catalysts, various types of carbon nanofibers were obtained,
with the absence of the catalyst particles at their tip as a common characteristic. The IH
mode combined with the CCVD method seems attractive for the synthesis of carbon
nanostructures, allowing a significant decrease of energy consumption and of the overall
reaction time as compared with the heating mode with outer furnace. (Collaboration with
ITIM-Cluj-Napoca)
4. Hydrogen uptake by carbon nanofibers catalyzed by palladium
Carbon nanofibers of herringbone conformation were obtained by chemical vapor
deposition on Pd/La2O3 catalyst, from ethylene-hydrogen mixture. After the removal of
La2O3, samples with various Pd/C ratios were obtained by oxidation in air. The hydrogen
sorption capacities measured gravimetrically at 10 MPa in pure hydrogen, for six different
batches of samples, show a good correlation with the Pd/C ratio reveling a catalytic effect
of Pd, which supplies atomic H. A possible charge transfer might lead to the increasing of
the H uptake with the increasing Pd/C ratio. A saturation value of 1.5% H (mass) per
carbon is reached at rather high Pd/C mole ratio (~ 1) for nano'bers with 425–455 m2g−1
BET surface area. (Collaboration with ITIM-Cluj-Napoca)
5. Local modes of Fe and Co atoms in NiAl intermetallics
Using nuclear inelastic scattering of synchrotron radiation and inelastic neutron scattering
we have investigated the vibrational properties of Fe and Co impurities in NiAl
intermetallics, and compared them with the density functional theory calculations. The Fe
phonon spectra show two sharp peaks appearing in the frequency gap between the Ni and
Al phonon bands, and originating from the local modes of Fe residing in Ni, or Al
sublattices. Co, which replaces Ni, vibrates within a narrow frequency interval occurring
close to the upper edge, but still within the Ni phonon band. The ab initio calculations
show that these effects are expected when impurity-host force constants differ from hosthost force constants causing a dynamic mismatch between guest and host vibrations.
(collaboration with Institute of Nuclear Physics - Polish Academy of Sciences, European
Synchrotron Radiation Facility (ESRF), Institute Laue Langevin, Grenoble)
6. Mechanical Spectroscopy of the Formation of Quasicrystalline Order in Rapidly
Quenched Ti- and Zr-based Alloys
The development of quasicrystalline (qc) order from different initial states (amorphous,
nano- or poly-qc) was studied in rapidly quenched Ti-Zr-Ni(-Ag), Ti-Zr-Fe, and Zr-Cu-Ni-
38
Al alloys by means of mechanical spectroscopy (vibrating-reed technique), including both
the irreversible changes of Young’s modulus and the Snoek-type relaxation peak of
absorbed hydrogen as a probe, which are obviously sensitive to quite different types of
ordering processes. The strongest annealing effects on Young’s modulus were found for
extreme nano-qc material at the amorphous limit, whereas order-induced narrowing of the
hydrogen peak occurs only at comparatively larger grain sizes. More important differences
in the properties of the hydrogen peak are found between quasicrystals of different
compositions. (Collaboration with Technical University of Braunschweig)
PROMOTED INTERNATIONAL COOPERATION & PROJECTS:
Bilateral agreement with Hochschule Wismar
Project title:
Structural and magnetoresistive effect investigations in double perovskites
Phase transition in shape-memory alloys
EU- funded, FP5 research project, Contract No. ENK6-CT-2001-00509:
Project title:
Nanostructured materials for lithium-based batteries.
1.B.Rohland, M.C.Bunescu, M.Pietrzak, M.Wienecke, T.Barfels, S.Möller – “CNT based cathode material for DMFC”, accepted at Fullerenes, Nanotubes and Carbon
Nanostructures, (2004)
2.P.Fedtke, M.Wienecke, M.C.Bunescu, T.Barfels, K.Deistung, M.Pietrzak, “YSZ films
deposited by plasma spraying and sputtering”, Journal of Solid State Electrochemistry, 8
626-632, (2004)
3.P.Fedtke, M.Wienecke, M.C.Bunescu, M.Pietrzak, K.Deistung, E.Borchardt,
“Hydrogen sensor based on optical and electrical switching”, Sensors and Actuators B
100 151-157, (2004)
4.A.Jianu, M.Valeanu, D.P.Lazar, F.Lifei, C.Bunescu, V.Pop, “Effects of Zr and Ti
substitutions on the crystallization processes and magnetic properties of Fe3B/Nd2Fe14B
nanocomposite magnetic system”, J. of Mag.& Mag. Mat. 272-276 1493-1495, (2004)
5.A.Jianu, M.Valeanu, D.P.Lazar, F.Lifei, M.Tomut, V.Pop, S.Alexandru,
“Crystallization processes of Fe3B/Nd2Fe14B nanocomposite magnetic system”, Rom
Rep.Phys 56, 435-439, (2004)
6.V.Kuncser, M.Valeanu, F.Lifei, A.Jianu, W.Kappel, G.Filoti “Local magnetic
Interactions in Fe/RE2Fe14B nanocomposite systems” Phys. Stat Solidi. ( c ) 1 3503-3506,
(2004)
39
7.M.Sorescu, L.Diamandescu, M.Valeanu, A.Jianu, “Effects of cobalt substitutions in
spring magnets” J. of Materials Science 39, 7387-7389, (2004)
8.V.Kuncser, M.Valeanu, F.Lifei, A.Jianu, D.Predoi M.Codescu, W.Kappel, G.Filoti
“Micro-structure and magnetic properties of Fe-Cu nanocomposites as potential
candidates for R E-Free permanent magnets” J.of Alloys and Commpounds (in proof)
9.K.Parlinski, P.T.Jochym, O.Leupold, A.I.Chumakov, R.Rüffer, H.Schober, A.Jianu,
J.Dutkiewicz and W.Maziarz, “Local modes of Fe and Co atoms in NiAl intermetallics”,
Phys. Rev. B 70, 224304, (2004)
10.D.Lupu, A.Biris, I.Misan, A.Jianu,“Hydrogen uptake by carbon nanofibers catalyzed
by palladium”, Int. J. Hydrogen Energy 29/1 97, (2004)
11.D.Lupu, A.R.Biris, A.Jianu, E.Burkel, M.C.Bunescu, G.Mihailescu, S.Pruneanu,
L.Olenic, I.Misan, “Carbon nanostructures produced by CCVD with induction heating”
Carbon 42/3 503, 2004
12.A.Jianu, H.-R.Sinning, E.Burkel, “Solid-solid phase transformation of amorphous
titanium based alloys”, Solid State Transformation and Heat Treatment, ed. Alain Hazotte
(ISBN 3-527-31007-X - Wiley-VCH, Weinheim), 145, (2004)
13.H.-R.Sinning, I.S.Golovin, A.Jianu, “Mechanical spectroscopy of quasicrystal
formation from amorphous Ti- and Zr-based alloys”, Solid State Transformation and Heat
Treatment, ed. Alain Hazotte (ISBN 3-527-31007-X - Wiley-VCH, Weinheim), 135,
(2004)
CONFERENCES:
1.B.Rohland, M.Pietrzak, S.Möller, M.C.Bunescu, M.Wienecke, “Development of carbon
nanotubes electrodes for small power DMFC – units”, Proceed. International Hydrogen
Energy Forum, 25–28 May, Beijing, China, vol. 1, p. 311, (2004)
2.M.Wienecke, M.C.Bunescu, M.Pietrzak, K.Deistung, H.Hansmann “Conductive
polymer nano-composites” E-MRS 2004 Spring Meeting, Strasbourg, May 24-28,
I/PII.34, (2004)
3.Petra Fedtke, T.Barfels, Marion Wienecke, M.C.Bunescu, K.Deistung “LSM/YSZ/YSZNi structure - microstructure and electrical analyses”, OSSEP/ESF-Workshop on
Electrode Processes and Kinetics in SOFCs, Roma, Italy, February 19-21, (2004)
4.M.Wienecke, M.C.Bunescu, K.Deistung, P.Fedtke, E.Borchartd “MWCNT coatings
obtained by thermal CVD using ethanol decomposition”, EMRS Spring Meeting 2004, ,
24th - 28th May 2004 Strasbourg, France.
40
5.V.Kuncser, M.Valeanu, F. Lifei, A.Jianu, W.Kappel, O.Crisan, G.Filoti, “Local
magnetic interactions in Fe/Nd2Fe14B nanocomposite systems”, The Second Seeheim
Conference on Magnetism (SCM2004) June 27-July 01, (2004)
D. GROUP OF NEW SYTEMS WITH IONIC AND CO-ORDINATION BOND
HEAD: CARMEN PLAPCIANU
E-mail : [email protected]
Tel : (+4021) 493 01 95
Fax : (+4021) 493 02 67
TOTAL EMPLOYEES: 3
RESEARCH TEAM: 2
1.Carmen PLAPCIANU
2.Cristina VALSANGIACOM
3.Gheorghe GHEORGHE
researcher
technical assistant
1. The synthesis of perovskite type oxides
SrxMnO3 compounds)
( Sr2FeMoO6, Sr2FeMo1-xWx O6 and La1-x
2. The characterization of species by elemental chemical analysis, TDA, IR spectroscopy,
XRD, Mössbauer spectroscopy and SEM in Mn+ -STA systems (where Mn+-metallic ion and
STA-surfactant).
1.L.Stanciu, J.R.Groza, L.Stoica, C.Plapcianu, “Influence of powder precursors on
reaction sintering of Al2TiO5”,Scripta Materialia 50, 1259-1262, (2004)
2.C.Valsangiacom, M.Sima, D.Predoi, C.Plapcianu, C.Kuncser, G.Schinteie, M.Bulinski,
“A microscopic analyze of the conduction mechanism of iron doped polyanilina under the
UV exposure”, Rom.Rep. Phys. 56(4), 645-650, (2004)
CONFERENCES :
1.L.Stoica, C.Plapcianu, R.Cosmeleata, C.Valsangiacom, “Ti(IV) oxides precursorspotential components for some materials” International Conference Biomaterial &
Biomedical Devices”, November 5-7th 2004
2.A.Ioachim, M.I.Toacsen, M.G.Banciu, L.Nedelcu, D.Ghetu, M.Feder, C.Plapceanu,
F.Lifei, “Synthesis and dielectric properties of Ba(Zn1/3 Ta2/3)O3 ceramics”, A XI a Sesiune
de Comunicari Stiintifice cu Participare Internationala, Academia Fortelor Terestre
“Nicolae Balcescu”, Sibiu, Romania, noiembrie 2004
41
Laboratory of Low-Dimensional Systems
HEAD: Dr. MAGDALENA LIDIA CIUREA
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 43
RESEARCH TEAM: 35
A.GROUP OF THEORETICAL PHYSICS: CONDENSED MATTER
HEAD: Dr. ALEXANDRU ALDEA
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 7
RESEARCH TEAM: 7
1.
2.
3.
4.
5.
6.
7.
Dr. Alexandru ALDEA,
Dr. Andrei MANOLESCU,
Dr. Paul GARTNER,
Dr. Marian NITA,
Dr.Valeriu MOLDOVEANU,
Ion-Viorel DINU, Ph.D. Cand.
Mugurel TOLEA, Ph.D. Cand.
senior researcher I
senior researcher I
researcher
Quantum transport in mesoscopic systems: charge and spin effects
Disorder and interaction effects on the orbital and spin magnetization in meso-systems
Mathematical aspects of mesoscopic transport
Quantum interference and correlations in mesoscopic systems: Fano and Kondo effects
1. A detailed description of the tunneling properties of coupled dot systems in the
presence of electron-electron interactions and magnetic field.
2. The rigorous justification of the Landauer-Buttiker formalism for the electron
propagation through mesoscopic systems.
42
- Project title:”Charge and spin effects in confined electron systems”; Partner: Univ.
Bilkent, Ankara.
- Project title:”Electrical and optical properties of Semiconductor heterostructures”;
Partner: Instituto de Ciencia de Materiales Madrid.
- Project title: ”Mesoscopic Physics”; Partner: Inst.Fuer Th., Physik, Univ. Koeln
- Project title: ”Magnetism and dynamic phenomena in meso-physics”; Partner:Univ.
Rejkyavik
1.
M.Nita, V.Dinu, A.Aldea, B.Tanatar, „Spin magnetization of a strongly correlated
electron gas confined in a two-dimensional finite lattice”, Phys. Rev. B 69, 073106
(2004)
2.
V.Moldoveanu, A.Aldea, B.Tanatar, „Tunneling properties of quantum dot arrays in
strong magnetic field”, Phys. Rev. B 70, 085303 (2004)
3.
A.Aldea, M.Nita, V.Dinu, M.Tolea, “Disorder effects on the properties of the 2D
finite systems in perpendicular magnetic field: the tight-binding approach”, Phys. Stat.
Sol. – b 241, 2089 (2004)
4.
A.H.D.Cornean, A.Jensen, V.Moldoveanu, “A rigorous proof of the Landauer –
Buttiker formula”, accepted in J. Math. Phys.
5.
T.R.Nielsen, P.Gartner, F.Jahnke, “Many-body theory of carrier capture and
relaxation in semiconductor quantum-dot lasers”, Phys.Rev.B 69, 235314 (2004)
6.
N.Baer, P.Gartner, F.Jahnke, “Coulomb effects in semiconductor quantum dots”, Eur.
Phys. J. B 42, 231 (2004)
7.
S.S.Gylfadottir, M.Nita, V.Gudmundsson, A.Manolescu, “Net current generation in a
1D quantum ring at zero magnetic field”, accepted in Physica E
8.
J.Seebeck, T.R.Nielsen, P.Gartner, F.Jahnke, “Polarons in semiconductor quantum
dots and their role in the quantum kinetics of carrier relaxation”, accepted in
Phys.Rev.B
CONFERENCES:
1.
H.D.Cornean, A.Jensen, V. Moldoveanu, „A mathematical look on the LandauerButtiker formula”, QMATH 9, Giens-France 11-17 September 2004
2.
F.Bentosela, P.Duclos, V.Moldoveanu, G.Nenciu, „The dynamics of 1D Bloch
electrons in constant electric fields”, QMATH 9, Giens-France 11-17 September 2004
43
A.Aldea, M.Tolea, V.Dinu, „Effects of the spin interaction on the interference
properties of Aharonov-Bohm rings”, „Conference on new concepts and materials for
molecular electronics and nanotechnology”, Puszczykowo (Poznan), 11-15 September
2004
4. V.Dinu, M.Tolea, „Solving the Kondo problem for complex mesoscopic systems”, „2nd
National Conference on Theoretical Physics”, 26-29 August 2004 Constanta
(Romania), accepted to Rom. Journ. Phys
3.
PhD THESES:
1.V.Moldoveanu, „Contributions to the mathematical theory of transport phenomena”,
Centre de Physique Theorique de Marseille.
2.M.Nita, „Magnetotransport in 2D mesoscopic systems”, University of Bucharest.
1.Ph.D. candidates: V.Dinu, M.Tolea.
B. GROUP OF STRUCTURE AND THIN FILMS
HEAD: Dr. DAN MACOVEI
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 8
RESEARCH TEAM: 7
Dr. Dan MACOVEI
Dr. Cristian-Mihail TEODORESCU
Dr. Radian POPESCUa
Dr. Florin ZAVALICHEb
Magdalena CONSTANTINc, Ph.D. cand.
6. Sorin Avram POENARIUd, Ph.D. cand.
7. George Adrian LUNGU, Ph.D. cand.
1.
2.
3.
4.
5.
a
- Temporary address: Max Planck Institute for Microstructure Physics, Halle, Germany
- Temporary address: University of California, Berkeley, USA
c
- Temporary address: University of Maryland, College Park, Baltimore, USA
d
- Temporary address: Ruhr University, Bochum, Germany
b
44
- Structure and magnetic properties of metal nano–particles in co-evaporated metalfullerene thin films
- Structure of quasicrystalline (icosahedral) Al-Mn alloys with rare earths
- Magnetic metal-semiconductor interfaces and diluted magnetic semiconductors
- Metal environment in supported catalysts
1.
Experimental evidence, by magnetic circular dichroism in x-ray absorption (XMCD
spectroscopy), of the bulk-surface antiferromagnetism of Ni nano-particles embedded
in C60 thin films.
2.
Structural model of the icosahedral phase in AlMnRE (RE = rare earths) alloys. Chemical ordering of the structure, by preferential RE distribution on specific sites.
3. Structure and magnetism of the Fe/InAs(100) interface: interface development during
the Fe-layer growth, interstitial magnetic moments, structure relaxation towards bcc
Fe.
- Project Title: “Structure investigations by X-ray techniques of new materials of
crystalline, quasicrystalline and disordered structure” (2003-2007); Partner: Beijing
Electron-Positron Collider (BEPC) National Laboratory, Beijing, China
- Project Title: “Structure, electronic and magnetic properties of materials and systems
based on combining magnetic metals and semiconductors: metal-semiconductor
interfaces, ferromagnetic semiconductors, highly magnetic polarized semimetals” (20032007); Partner: Laboratoire de Physique de la Matière Condensée, Université CergyPontoise, France
PAPERS PUBLISHED OR ACCEPTED FOR PUBLICATIONS IN 2004:
1.
C.M.Teodorescu, D.Macovei, A.Lungu, “Structural and magnetic investigations of
nickel clusters in C60 matrices”, J. Optoel. Adv. Mater. 6, 1275 (2004)
CONFERENCES:
1.
D.Macovei, R.Popescu, C.M.Teodorescu, A.Lungu, “Structure ordering in nanoicosahedral Al-Mn alloys with rare earths”, Nat. Workshop Nanoscience and
Nanotechnologies, Jan. 27, 2004, Bucharest, Romania.
2.
C.M.Teodorescu, D.Macovei, A.Lungu, ”Nano-structured Ni-fullerene thin films:
structure and magnetic properties”, Nat. Workshop Nanoscience and
Nanotechnologies, Jan. 27, 2004, Bucharest, Romania.
45
3.
D.Macovei, “Structure of AlMnRE (RE=rare earths) icosahedral phases and alternate
mehtods of preparation of nano-crystalline aloys”, 4th Nat. Symp. MATNANTECH,
Feb. 18-22, 2004, Busteni, Romania.
4.
C.M.Teodorescu, D.Macovei, A.Lungu, “Structure, electronic properties, and
magnetism of Ni and Fe nanoparticles embedded in C60 matrices”, 7th Intern. Conf.
Physics of Advanced Materials, June 10-12, 2004, Iasi, Romania.
5.
C.M.Teodorescu, D.Macovei, A.Lungu, “Structure and magnetic investigations of
nickel nanoparticles in C60 matrices”, 5th Intern. Balkan Workshop for Applied
Physics, July 5-7, 2004 Constanta, Romania.
6.
D.Macovei, C.M.Teodorescu, A.Lungu, V.A.Şerban, A.Răduţă, C.Codrean, C.Firu,
M.Călin, “Nano-icosahedral and nanocrystalline Al alloys”, 4th Nat. Workshop
Conceived in Romania - CONRO 2004, Oct. 5-10, 2004, Bucharest, Romania.
7.
D.Macovei, C.M.Teodorescu, A.Lungu, ”Interface effects in metalC60 nanostructures”, 4th Nat. Workshop Conceived in Romania - CONRO 2004, Oct. 510, 2004, Bucharest, Romania.
Ph.D. student: Sorin Avram Poenariu (Ruhr Univ., Faculty of Electrical Engineering
and Information Techniques, Bochum, Germany)
Subject: “Electrical transport in semiconductor nanostructures”.
Ph.D. student: George Adrian Lungu (National Institute of Materials Physics,
Bucharest)
Subject: “Structure and properties of metal-C60 thin films”.
C. GROUP OF THIN FILMS AND QUANTUM STRUCTURES
HEAD: Dr. Toma STOICA
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 8
RESEARCH TEAM: 6
1.
2.
3.
4.
5.
6.
Dr. Toma STOICA
Dr. Constantin MOROSANU
Dr. Tionica STOICA
Dr. Mihail LEPSA
Dr. Paul Nicolae RACEC
Adrian SLAV, Ph.D. Cand.
senior researcher I
46
- Growth and optoelectric properties SiGe and GaN nanostructures;
- Experimental investigation of quantum transport in nano resonant tunneling
semiconductor structures;
- Electronic transport theory of semiconductor nanostructures;
- Wide-gap semiconductor thin films obtained by sol gel procedures;
- Studying of bioactive and hemocompatible ceramic thin films: obtaining of bioactive
HA surfaces witch could differentiate preosteblast in osteblats cells for coating titanium
substrates; obtaining and studying of various amorphous carbon films as
hemocompatible coatings.
MAIN SCIENTIFIC RESULTS OBTAINED IN 2004
1.
Properties of single-isolated Ge dot obtained by selective epitaxy
2.
Optimization of the graded gap injector of Gunn diodes used in adaptive cruise control
systems
3.
Resonance quantum theory for the capacitance of the MIS nanostructures
4. Optical and structural characterizations of multilayers transparent ITO sol-gel films
deposited onto silicon substrates
5. Bioactive HA surfaces which promote the proliferation of various cell cultures for in
vivo-tests
- Project Title: "Study of chemical growth process in physiological media onto
calcium phosphate base layers sputtered on varoius biocompatible substrates"(20042005); Partner: Aveiro University, Aveiro, Portugal
- Project Title: "Doped and undoped carbon films"(2004-2005); Partner:AF Ioffe
Institute, St. Petersburg, Rusia
1.
T.Stoica, L.Vescan, E.Sutter, "Absence of island–island interaction during formation
of isolated Ge islands in small windows”, J. Appl. Phys. 95, (2004)
2.
V.Nelea, C.Morosanu, M.Iliescu, I.N.Mihailescu, "Hydroxyapatite thin films grown
by pulsed laser deposition and RF magnetron sputtering: a comparative study", Appl.
Surface Science, 228, 346, (2004)
47
3.
L.Verestiuc, C.Morosanu, I.Pasuk, M.Bercu, I.N.Mihailescu, "Chemical growth of
calcium phosphate layers on magnetron sputtered HA films", J. Crystal Growth, 264,
483, (2004)
4.
S.G.Yastrebov, V.I.Ivanov-Omskii, V.A.Kosobukin, F.Dumitrache,C.Morosanu,
“Spectra of Raman Scattering from amorphous carbon modified with iron”, Technical
Phys. Lett., 30, 995, (2004)
5.
L.Rosu, C.N.Cascaval, C.Ciobanu, D.Rosu, E.D.Ion, C.Morosanu, M.Enachescu,
“Effect of UV radiation on the semi-interpenetrating polymer networks based on
polyurethane and epoxy-maleate of bisphenol”, J. Photochem. Photobiol. A, Chemistry
169, 177, (2004)
6.
T.F.Stoica, M.Gartner, M.Losurdo, V.Teodorescu, M.Blanchin, T.Stoica,
M.Zaharescu, “Spectroellipsometric study of the sol–gel nanocrystalline ITO
multilayer films”, Thin Solid Films 455 –456, 509, (2004)
7.
G.A.Nemnes, U.Wulf, P.N.Racec, "Nanoscale transistors in the Landauer-Büttiker
formalism", J. Appl. Phys. 96, 596, (2004)
8.
S.G.Yastrebov, V.I.Ivanov-Omskii V.Pop, C.Morosanu, A.Slav, J.Voiron, “Magnetic
properties of amorphous carbon modified with iron”, accepted to Semiconductors, dec.
(2004)
CONFERENCES:
1.
L.Zdrentu, A.Slav, C.Morosanu, S.Petrescu, “In vivo studies onto nonocrystallized
HA sputtered films”, “From Solid State to Biophysics”, June 26-July2, 2004,
Dubrovnik, Croatia.
2.
L.Zdrentu, A.Slav, C.Morosanu, S.M.Petrescu, M.Bercu, „The cytocompatibility of
nanocrystallized HA sputtered films”, „Biomaterials & Medical Devices” November 57 2004, Bucharest.
3.
F.N.Oktar, C.Morosanu, E.Z.Erkmen, L.S.Özyeğin, I.Peker, R.Saban, B.Sennaroglu,
H.Haybat, “Sintering of synthetic hydroxyapatite compacts”, „Biomaterials & Medical
Devices” November 5-7 2004, Bucharest.
4.
S.Ciuca, I.Mercioniu, M.Tarcolea, M.Bercu, A.Slav, C.Morosanu, "Effect of post
deposition heat treatments on RF magnetron sputtered hydroxyapatite coatings”,
„Biomaterials & Medical Devices” November 5-7 2004, Bucharest.
5.
S.G.Yastrebov,V.A.Kosobukin, V.I.Ivanov-Omskii, C.Morosanu, "Impact of iron
nanoclusters on Raman spectra of amorphous carbon", lV International Conference of
Amorphous&Microcrystalline Semiconductors, July 5-7, 2004, St. Petersburg, Rusia.
6.
P.N.Racec, E.R.Racec, U.Wulf, "Application of R-matrix formalism in modeling of
semiconductor nanostructures" Workshop "Advances in Modeling and Simulation of
48
Semiconductor Devices", AMaSiS 04, Weierstrass Institute for Applied Analysis and
Stochastics, July 14-16, 2004, Berlin, Germany.
1. Ph.D. candidates: Adrian Slav: PhD Thesis: "Study of interface phenomena in the
biocompatible structures"
2. M. Sc. student: Adrian Slav, Master thesis: “Biocompatible structures of hydroxyapatite
for orthopedic application”
3. Diploma Thesis: "Effect on annealings on the properties of the hydroxyapatite sputtered
films (Ionel Mercioniu-Materials Science Faculty, Politechnica University)
D. GROUP OF SILICON-BASED MICRO- AND NANOSYSTEMS
HEAD: Dr. MAGDALENA LIDIA CIUREA
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 7
RESEARCH TEAM: 6
1.
2.
3.
4.
5.
6.
Dr. Magdalena Lidia CIUREA,
Dr. Sorina LAZANU,
Dr. Mariana LAZAR KLEIN1
Mihai DRAGHICI2
Lucian JDIRA3
Ionel STAVARACHE,
senior researcher I
researcher
1
Temporary address: University of Wisconsim Madison, Department of Physics,USA
Temporary address: Ruhr Universität Bochum, Germany
3
Temporary address: Research Institute for Molecules and Materials, Nijmegen
University, Holand
2
- Electrical and photoelectrical transport mechanisms in silicon-based nanomaterials
and nanostructures: experimental and modeling
- Electronic processes related to defects in nanomaterials: experimental and simulation
- Physics of semiconductors in radiation fields: defect formation and kinetics, role of
impurities in the radiation hardness, stability of defects, influence of irradiation and
storage conditions
49
1.
Corelation between microstructure results and transport modeling calculations in
Si/SiO2 nanocomposites
The nanocrystallite sizes from HRTEM are in good agreement with the results obtained
from the modeling of current-temperature curves; also, the amorphous intercrystallite
sizes fit very well with the results for current-voltage characteristics.
2.
Surface contributions to nanocrystalline silicon properties
Surface contributions to electrical transport and photoluminescence were separated
from the bulk ones.
3. Contributions of primary defects to the leakage current of silicon detectors were first
time considered. The existence of a “background” in the leakage current after irradiation, source of discrepancies between data and previous model calculations, was tentatively attributed to the SiFFCD defect.
- Project title: “Transport in novel semiconductors” (2001 – 2004); Partner: The Racah
Institute of The Hebrew University Jerusalem, Israel
- CERN RD50 Collaboration “Radiation hard semiconductors for very high luminosity
colliders” http://cern.ch/rd50
- Project title: “ Radiation effects on semiconductor materials “(2003 – 2005); Partner:
University of Florence , Italy
1.
V.Iancu, M.Draghici, L.Jdira, M.L.Ciurea, “Conduction mechanisms in siliconbased nanocomposites”, J.Optoelectron. and Adv. Mater. 6 (1), 53, (2004)
2.
S.Lazanu, I.Lazanu, “Systematic study related to the role of initial impurities and irradiation rates in the formation and evolution of complex defects in silicon for detectors
in HEP experiments”, Physica Scripta. 69, 376, (2004)
3.
I.Lazanu, S.Lazanu, “Silicon detectors operating beyond LHC conditions: scenarios
for radiation fields and detector degradation”, Rom. Rep. Phys. 56, 689, (2004)
4.
I.Lazanu, S.Lazanu, “Estimated modifications of the characteristicsof silicon
detectors duet o their use at the LHC accelerator and in AMS space conditions”,
Roum. Rep. Phys. 56, 343, (2004)
5.
CERN RD50 Collaboration: M.Bruzzi, ..., S. Lazanu, ..., „RD50 Status Report 2004-
50
Radiation hard semiconductor devices for very high luminosity colliders”, CERNLHCC-2004-031 and LHCC-RD-005.
6.
CERN RD50 Collaboration: Panja Luukka, …, S. Lazanu, …,”Status of defect
engineering activity of the RD50 collaboration”, Nucl. Instr. Meth. Phys. Res. A 530,
152, (2004)
7.
CERN - RD50 Collaboration: M.Bruzzi, ., S. Lazanu, …, ”Material engineering for
the development of ultra-radiation hard semiconductor detectors” Nucl. Instr. Meth.
Phys. Res. A 518, 336-337, (2004)
8.
CERN - RD50 Collaboration: M.Bruzzi, ..., S. Lazanu, ...,” Radiation tolerant
materials for semiconductor detectors at SuperLHC”, accepted Nucl. Instr. Meth.
Phys. Res. A 518, 336, (2004)
CONFERENCES:
1.
M.L.Ciurea, V.Iancu, I.Stavarache, ”Quantum confinement in conduction and
photoluminescence of nanocrystalline porous silicon”
Presented to National
Simposium "Inginerie si nanostiinte" , April 23, 2004, „Politehnica” University of
Bucharest, Bucharest, Romania.
2.
V.S.Teodorescu, M.L.Ciurea, V.Iancu, M.G.Blanchin, “ Microstructure of Si/SiO2 nanocomposite films”, Int. Semicond. Conf. CAS 2004, Sinaia, Romania, October 3-6,
2004, Proc. IEEE CN 04TH8748, 1, 59, (2004)
3.
S.Lazanu, I.Lazanu, M.L.Ciurea, “Influence of crystal growth technology on the tolerance to radiation of silicon for detectors at future accelerators”, Int. Semicond.
Conf. CAS 2004, Sinaia, Romania, October 3-6, 2004, Proc. IEEE CN 04TH8748, 2,
419, (2004)
4.
I. Lazanu S. Lazanu, “Silicon detectors operating beyond LHC conditions: scenarios
for radiation fields and detector degradation”, 2004 Annual Scientific Conference,
Faculty of Physics, University of Bucharest, Bucharest, May 2004, Rom. Rep. Phys.
56, 689, (2004)
5.
I. Lazanu S. Lazanu “Some possible explanations of the discrepancies in the results of
modelling the leakage current of detectors after hadron irradiation”, Int. Conf. on
Radiation Effects on Semiconductor Materials, Detectors and Devices, Florence, Italy,
October 2004
6.
CERN RD50 Collab: A. Calderoni,…., S. Lazanu, „Radiation-hard detectors for very
high luminosity colliders”, Int. Conf. Vertex 2004, Como, Italy, September 2004 accepted at Nucl. Instr. Meth. Phys. Res. A.
7.
CERN RD50 Collab. E. Fretwurst,…, S. Lazanu, “Recent advancement in the
development of radiation hard semiconductor detectors for very high luminosity for
very high luminosity colliders colliders - the RD50-collaboration”, Int Conf. on
51
Radiation Effects on Semiconductor Materials, Detectors and Devices, Florence, Italy,
Oct. 2004
8.
CERN - RD50 Collaboration M.Bruzzi,…., S. Lazanu,….,”Recent results on
radiation radiation hard semiconductor hard semiconductor detectors detectors for
superLHC”, IEEE Nuclear Science Symp. 2004, Rome, Italy, Oct. 2004, to be
published in IEEE Trans. Nucl. Sci.
BOOKS:
M.L.Ciurea, M.Draghici, L.Jdira, V.Iancu, M.R.Mitroi, I. Kleps, A. Angelescu, M. Miu,
M. Simion, “Surface contribution to the trapping phenomena in nanocrystalline silicon
structures”, Series in Micro and Nanoengineering vol.: Advances in Micro- in
Nanoengineering, 89 - 110 , Editura Academiei Romane 2004.
- Ph.D. candidates: Mihai Draghici, Lucian Jdira
- M. Sc. student: Ionel Stavarache
E. GROUP OF GAS SENSORS
HEAD: ADELINA TOMESCU
Tel: (+4021) 493 01 95
Fax:(+4021) 493 02 67
TOTAL EMPLOYEES: 9
RESEARCH TEAM: 6
1. Adelina TOMESCU
2. Dr. Nicolae BARSAN,
3. Dr. Alexandru OPREA,
4. Razvan Mihai ROESCU
5. Dumitriu IRINA
- Development and characterisation of micro and nano-structured metal oxides with
catalytically active dopants for the devices, which is intended for sensitive and selective
52
measuring of CO, CH4, NOx in air. These materials will be prepared in the form of thin
and thick films.
- Complex laboratory investigations of the micro and nano-structured materials by
considering specific application scenarios in environmental control and protection
(indoor and outdoor air monitoring), focused on regional problems.
- Development of low cost and low power consumption devices based on the prepared
micro and nano-structured materials deposited on ceramic substrates. The main focus
will be on the ceramic-based substrates in order to ease the technological transfer.
Sensors tailored for industrial process control, environmental monitoring and civil
protection applications are stringent necessary.
1.
Obtaining a multi-functional tin oxide sensor with enhanced sensitivity to target gas
(CO and CH4) by tuning of temperature of active layer through the built-in heater
Complex investigations of MOS sensors can be carried out by means of simultaneous
monitoring of two physical parameters: conductance (resistance) along with work
function variations ∆Φ, thermal effect ΔT and catalytic combustion
3. Studies for elaboration of an Evaluation Procedure for Gas Sensors used in
Environmental Monitoring Applications
2.
The elaboration and implementation of an evaluation procedure for the gas sensors
which are required in environmental monitoring applications responds to the direct
requests of the scientists, industrial users of the sensors and electronic environmental
monitoring devices, producers and last but not least creates the premises for the
accreditation of Gas Sensors Laboratory.
- Scientific Cooperation Agreement between the Gas Sensors Research Group at the
Institut fuer Physikalische und Theoretische Chemie, Eberhard Karls Universitaet
Tuebingen, GERMANY and the Gas Sensors Group, Department of Low
Dimensionality Systems , at the National Institute of Materials Physics, Bucharest,
Romania.
1. R.Roescu, I.Dumitriu, A.Tomescu, “Simultaneous evaluation of the electricalresistens
and work functionchanges for resisctor type sensors ”, Rom. Rep. Phys. 56, 607, (2004)
CONFERENCES:
1. A.Tomescu, R.Roescu, I.Dumitriu, D.Tarabasanu-Mihaila, “Gas sensing properties of
mixed αFe2O3 – SnO2 nanoparticles prepared under hydrothermal conditions “, Int.
53
Semicond. Conf. CAS 2004, Sinaia, Romania, October 3-6, 2004, Proc. IEEE CN
04TH8748, 1, 59, (2004)
2. C.Moldovan, R.Iosub, A.Tomescu, M.Bercu, “Micromachined chemoresistive sensors
for CO and CH4 detection”, Int. Semicond. Conf. CAS 2004, Sinaia, Romania, October
3-6, 2004, Proc. IEEE CN 04TH8748, 1, 275, (2004)
3. C.Moldovan, R.Iosub, A.Tomescu, M.Bercu, S.Sosin,“Micromachined chemoresistive
sensors for CO detection”, Sensors for Security Workshop, ISPRA, June14-15, Italy.
4. A.Tomescu, I.Dumitriu, R.Roescu, “Temperature modulation for sensitive gas
detection based on SnO2-Pd sensors”, National Simposium of Theoretical
Electrotechnics SNET’04, Bucharest, October 22-23, (2004)
5. R.Roescu, A.Tomescu, L.Diamandescu, V.Teodorescu, C.Moldovan, “Metal oxide
gas sensors – a solution for industrial process control and environmental monitoring”,
GOSPEL School (General Olfaction and Sensing Projects on a Europen Level), Ustron,
Poland, September 22 – October 03, (2004)
- Ph.D. candidates: Adelina Tomescu, Razvan Mihai Roescu, Dumitriu Irina.
F. GROUP OF X-RAY DIFFRACTION, LB FILMS AND
COMPUTER-ASSISTED MODELLING OF AMORPHOUS SOLIDS
HEAD: Dr. MIHAI A. POPESCU
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 4
RESEARCH TEAM:
1.
2.
3.
4.
4
Dr. Mihai A. POPESCU
Dr. Adam LÖRINCZI
Dr. Mihaela Catalina STEGARESCU
Florinel SAVA
senior researcher I
researcher
1. Amorphous and disordered solids
2. Modeling of nanostructures and of amorphous structures (chalcogenides)
3. Chalcogenides alloys and photo-structural transformations
4. Thin amorphous PLD films based on piezoelectric and luminescent materials
5. Langmuir-Blodgett films
54
1. Thin films deposited by PLD based on mixed chalcogenide-organic material
Selenium – sulphur alloys doped by 10 at.% paraffins have been prepared as solid
targets for the preparation of thin films by pulsed laser deposition (PLD). The films
were studied by X-ray diffraction and ellipsometric method. The structure and
properties (refractive index, thickness, phase composition after annealing) of the films
were investigated. The possibility to inscribe the optical information on such films was
tested with promising results.
2. Atomic scale modelling of mixed carbon nano-configurations: fullerene-nanotubules
Several models of nanotubule-fullerene configurations have been developed and their
structures at the atomic scale were got by energy relaxation. It was concluded that the
mixed configuration corresponding to the attachment of a fullerene molecule C60 to a
nanotubule of carbon is stable. Therefore such combinations useful for making the
connections in nano-devices are possible and, therefore, can be practically realized.
3.
Structural modeling of amorphous As2S3
Various closed clusters were modeled. A new model of a-As2S3, based on closed
clusters has been developed.
- Project title: “Semiconducting chalcogenide glasses, nano-structured materials and
other complex materials” ; Partner: Lviv Scientific Research Institute of Materials of
Scientific Research Company “Carat”, Lviv, Ukraine
- Project title: “Non-crystalline and crystalline semiconductors and complex oxides
doped by rare-earth elements prepared as thin films”; Partner: Technical University
Chemnitz, Germany
- Project title: “Optical and complementary researches on new chalcogenide
glasses”; Partner: Indian Institute of Science, Bangalore, India
- Project title: “Development of high-resolution inorganic photoresists”; Partner:V.E.
Lashkaryov Institute of semiconductor physics, Kiev, Ukraine
1.
L.Ion, S.Antohe, M.Popescu, F.Scarlat, F.Sava, F.Ionescu, “Structure and electrical
properties of electron irradiated CdSe thin films”, J. Optoelectron. Adv. Mater., 6,
113, (2004)
55
2.
M.Popescu, F.Sava, A.Lőrinczi, I.N.Mihailescu, G.Socol, E.Axente, I.Kaban,
W.Hoyer, “Amorphous thin films based on paraffin doped chalcogenides prepared by
pulsed laser deposition”, J. Optoelectron. Adv. Mater., 6, 163, (2004)
3.
A.Lőrinczi, M.Popescu, F.Sava, A.Anghel, “Modelling of the the complex carbon
structure: fullerene – nanotubule”, J. Optoelectron. Adv. Mater., 6, 349, (2004)
4.
A.Lőrinczi, M.Popescu, F.Sava, “Possible nano-tube configurations in arsenic
chalcogenides”, J. Optoelectron. Adv. Mater., 6, 489, (2004)
5.
M.Popescu, F.Sava, A.Lőrinczi, R.Savastru, D.Savastru, R.Radvan, I.N.Mihailescu,
G.Socol, “Optical recording in sulphur-selenium layers”, J. Optoelectron. Adv.
Mater., 6, 883, (2004)
6.
M.Popescu, F.Sava, A.Lőrinczi, “Modelling of large molecular clusters in the noncrystalline As2S3”, J. Optoelectron. Adv. Mater., 6, 887, (2004)
7.
M.Popescu, F.Sava, H.Bradaczek, “Modeling of the amorphous diamond-like
carbon”, J. Phys. IV France, 118, 93, (2004)
8.
M.Popescu, W.Hoyer, M.Stegarescu, A.Cornet, N.Broll “Diffraction de rayons X sur
les plaquettes de fer durifiees par cyanuration”, J. Phys. IV France, 118, 351, (2004)
9. W.Hoyer, R.Kleinhempel, A.Lorinczi, A.Pohlers, M.Popescu, F.Sava, “Interstitial
void structure in Cu-Sn alloy as revealed from RMC modeling”, Journal of Physics:
Condensed Matter, accepted in (2004)
10. M.Popescu, F.Sava, A.Lőrinczi, A.Anghel ”Nano-structural configurations in As2S3
glass”, Phys. Chem. Glasses, accepted in (2004)
11. M.Popescu, “Photo-induced transformations in glass”, Chapter 5 of the book
“Semiconducting Chalcogenide Glass I; Glass formation, structure, and simulated
transformations in Chalcogenide Glass”, Eds. Robert Fairman, Boris Ushkov,
Semiconductor and Semimetals (Series), 78, 181, 2004
CONFERENCES:
1. M.Popescu, F.Sava, A.Lorinczi, M.Stegarescu, ˝Modelarea la scara atomica a unor
arhitecturi nanometrice˝, National Simposium "Inginerie si nanostiinte" , April 23,
2004, „Politehnica” University of Bucharest, Bucharest, Romania.
2. M.Popescu, ˝Photo-induced transformations in non-crystalline chalcogenides:
fundamentals and applications˝, Balkan Conference on Applied Physics, July 3-7, 2004,
Constanta, Romania.
3. M.Popescu, F.Sava, A.Lorinczi, “Modelling of the nanostructural architectures in
disordered atomic networks”, National Simposium “Mathematics in Engineering and
Numerical Physics”, 7-9 October 2004, „Politehnica” University of Bucharest,
Bucharest, Romania.
56
4.
M.Popescu, F.Sava, A.Lorinczi, A.Anghel, “Modelling of nano-structural
configurations in As2S3 glass, Presented to “The XIV-th International Symposium on
Non-Oxide and Novel Optical Glasses” ISNOG-14, November 2-9, 2004, Cape
Canaveral, Florida, USA.
PhD THESES:
- A. Lörinczi, Thesis : “Contributions to the study of the structure and structural
phenomena in non-crystalline chalcogenide materials”
- M. Stegărescu, Thesis : “Contributions to the study of special films: superconducting
(high Tc) and hard films”
- PhD students: Adam Lorinczi, Mihaela Stegarescu, Paul Barvinski, Coman Aurel,
Razvan Roescu.
- Diploma work: “Short range and medium range order in chalcogenide glasses”,
Alexandru Anghel (Faculty of Physics, University of Bucharest)
AWARDS:
Dr. M. Popescu was awarded with S. R. Ovshinsky Award for Excellence in NonCrystalline Chalcogenides, 2004
57
Laboratory of Optics and Spectroscopy
HEAD: Dr. LIGIA FRUNZA
E-mail: lfrunza@ infim.ro
Dr. MIHAELA BAIBARAC
E-mail:[email protected]
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 35
RESEARCH TEAM: 27
A.GROUP OF LIQUID CRYSTALS AND SURFACE INTERACTIONS
HEAD: Dr. STEFAN FRUNZA
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
RESEARCH TEAM: 8
1. Dr. Stefan FRUNZA
2. Dr. Ligia FRUNZA
3. Dr. Rodica MOLDOVAN1
4. Traian BEICA
5. Dr. Mihaela TINTARU2
6. Anatoli SERGHEI3
7. Irina-Ionela ZGURA
8. Irina NICOLAIE4
9. Felicia UNGUREANU
senior researcher I
senior researcher I
senior researcher I (guest)
1
present address: Institute of Mathematics „Simion Stoilow” of Romanian Academy
deceased October 2004
3
present adress: University of Liepzig, Germany; e-mail: [email protected]
4
moved from June to Sicomed SA, Bucharest.
2
1. Bulk nematic liquid crystals
Materials under investigation : cyanobiphenyl series n=5...8.
2. Composites containing nematic liquid crystals
Materials under investigation: mixtures of nematic liquid crystals and aerosil, having high
aerosil concentrations.
3. Hybrid systems containing organic compounds confined in nanoporous molecular sieves.
Potential applications in catalysis.
Materials under investigation : salen type or model compounds confined to molecular
sieves with nanopores/nanocavities.
4. Oxide systems, containing transition metal ions, with cubic structure and potential
57
applications in catalysis.
Materials under investigation: perovskites, ferrites, other spinel structures.
1. Lyotropic liquid crystals
In order to investigate the interfacial tension of some cyanobiphenyls (5CB, 7CB, 8CB) at
the interface with an isotropic liquid, an experimental set-up was realized, using the shape
variation of a hanging drop. The method precision was increased by using a video camera
to monitor the drop profile and a specially written program for the data processing. The
results obtained at the interface with glycerin were compared with those obtained at the airliquid crystal interface. Unusual behavior was found for the variation of interfacial tension
with the temperature due to several reasons: temperature dependence of the density,
orientation of the liquid crystal molecules at the interface with glycerin, or the different
ordering degrees in the superficial layer and inside the liquid bulk.
2. Composites containing liquid crystals and aerosol
The anchoring energy of the liquid crystal molecules onto a quartz substrate was discussed
for aerosil-cyanobiphenyl composites and for display cells with cyanobiphenyl and quartz
windows, as function of some energies more easily available such as the activation energy
for cyanobiphenyl desorption, determined from therogravimetric measurements and
desorption energy of cyanobiphenyl molecules determined from the temperature variation
of the superficial memory effects. In the former case, the obtained values, smaller than
usual, were explained due to considering only of the weak adsorption sites and of small
distances, instead of infinite ones. However, some established regularities were in
agreement with literature data and trends.
3. Organic compounds embedded in molecular sieves
Composites based upon salen type complexes (Jacobsen complex) or model compounds
(water complexes of manganese or terbium ions) and molecular sieves were prepared by
impregnation. The leaching of the complexes was checked by washing several times with
the solvent and monitoring the complex concentration in the washed solution. It resulted
that a small amount of Jacobsen complex remains still inside the pores. Photoluminescence
properties of Jacobsen complex were not evidenced; instead, the terbium ions (and
partially, the manganese simple ions) have shown their characteristic luminescence. The
corresponding transient times were fitted with exponentials and it was possible to attribute
these times to different species, as function of the hydration degree and ion location inside
the cavities of the molecular sieve.
4. Oxides of transition metal ions
Perovskites, ferrites, other spinel structures were prepared by classic and nonconventional
methods. The structure, composition and other physical properties of these materials were
investigated in relation with their physical applications. The catalytic properties are still
under testing.
58
- Partener in the EU Project 505834 CONCORDE (tip CA, FP6, NMP Priority 3): 20042006 “Co-ordination of nanostructured catalytic oxides research and development in
Europe“, Coordinator: Dr. Vicente Cortes Corberan {Consejo Superior de Investigaciones
Cientificas (ICP.CSIC), Spain} Resp. NIMP : Dr. Ligia Frunza
- Bilateral Cooperation "Surface effects in composites systems and guest – host interaction
in restricted geometry" between NIMP (Romania) and Bundesanstalt fuer
Materialforschung und-pruefung (BAM), Berlin, Germany, 2004-2006
PUBLISHED PAPERS:
1. L.Frunza, S.Frunza, I.Zgura, T.Beica, A.Schönhals, H.Kosslick, U.Bentrup, I. Pitsch,
“Confining effects in composites containing molecular sieves”, Mol. Cryst. Liq. Cryst.
416, 239-255 (2004)
2. S.Frunza, L.Frunza, M.Tintaru, I.Zgura, T.Beica, A.Schönhals, “Dynamics of
surface layer in cyanobiphenyl-aerosil nanocomposites with high silica density”, Liq.
Cryst. 31, 913-922 (2004)
3. L.Frunza, H.Kosslick, I.Pitsch, S.Frunza, A.Schönhals, C.Krause, F.Stallmach,
J.Kärger, “Water relaxation behavior inside the pores and cages of some molecular sieves
“, Proc. 14th International Zeolite Conference 2004, Cape Town, South Africa , CD p.
1721-1729, (2004)
4. T.Beica, R.Moldovan, M.Tintaru, I.Zgura, S.Frunza, „Measurements of optical
anisotropy of a calamitic liquid crystal”, Cryst.Res.Technol. 39, 149-154 (2004)
5. T.Beica, R.Moldovan, M.Tintaru, M.R.Puica, I.Zgura, S.Frunza, “Nematic isotropic
interfacial tension anisotropy of a calamitic lyotropic liquid crystal” , Liq. Cryst. 31, 325332 (2004)
6. R.Moldovan, M.Tintaru, M.R.Puica, T.Beica, I.Zgura, “Simple phenomenological
theory for the re-entrance phenomenon in lyotropic liquid crystals”, Rom. J. Phys.
(accepted 2004)
7. C.Tiseanu, L.Frunza, M.U.Kumke; "Time-resolved photoluminescence analysis of
distribution and migration of terbium ions in zeolites X", Physica B 352, 358-365 (2004)
8. M.N.Grecu, G.Burducea, V.V.Grecu, R.Moldovan, I.Zgura, T.Beica, „Temperature
modification of the ordering degree in the alkyl chain of ionic surfactants“ Revista de
Chimie, Bucharest, accepted (2004)
CONFERENCES:
59
1. L.Frunza, F.Marlow , S.Frunza, A.Schönhals, “Molecular dynamics inside the pores
of SBA-3 type molecular sieves”, 16 Deutsche Zeolith Tagung, Dresden, Germany , 3-5
March 2004, Poster RR02
2. L.Frunza, I.Nicolaie, S.Frunza, H.Kosslick, I.Pitsch, A.Dittmar, R.Fricke,
“Embedding a manganese(III) salen complex into nanoporous molecular sieves. Hostguest interactions”, 16 Deutsche Zeolith Tagung, Dresden, Germany, 3-5 March 2004,
Poster RR15
3. L.Frunza, H.Kosslick, I.Pitsch, S.Frunza, A.Schönhals, C.Krause, F.Stallmach,
J.Kärger, “Water relaxation behavior inside the pores and cages of some molecular
sieves”, 14th International Zeolite Conference 2004, Cape Town, South Africa , 25-29
April 2004, Oral
4. T.Beica, R.Moldovan, M.Tintaru, I.Zgura, S.Frunza, ”Interfacial tension of liquid
crystal/isotropic liquid interface”,20th ILCC 2004, Ljubljana, Slovenia, 4 – 9 Iulie, 2004,
Poster SURF-P063
5. L.Frunza, F.Marlow, A.Schönhals, S.Frunza, “Silica nanostructured composites
containing 8CB: Dynamical behaviour of 8CB molecules in the surface layer”, 20th ILCC
2004, Ljubljana, Slovenia, 4 – 9 Iulie, 2004, Poster SURF-P064
6. S.Frunza, L.Frunza, M.Tintaru, T.Beica, A.Schönhals, “Molecular dynamics of
surface layer in cyanobiphenyl-aerosil systems with high silica density”, 3rd International
Conference on Broadband Dielectric Spectroscopy and its Applications 2004, Delft,
Netherlands, 23-26 August 2004, Poster
7. L.Frunza, C.Tiseanu, I.Zgura, I.Nicolaie, T.Beica, S.Frunza, H.Kosslick, R.Fricke,
A.Dittmar “Spectroscopic and photoluminescence properties of a manganese(III) salen
complex embedded into nanoporous molecular sieves”, National Physics Conference, 7-10
september 2004, Pitesti , Romania, Poster
8. L.Frunza, I.Zgura, A.Schönhals, T.Beica, S.Frunza, “Desorption kinetics of surface
layer in aerosil-cyanobiphenil composites with high silica density”, National Physics
Conference, 7-10 september 2004, Pitesti , Romania, Poster
9. L.Frunza, S.Frunza, A.Schönhals, “Water behaviour in confined geometries”,
National Physics Conference, 7-10 september 2004, Pitesti , Romania, Oral
10. S.Frunza, L.Frunza, A.Schönhals, “On the glassy state of some liquid crystals of
cyanobiphenyl series”, Conferinta Nationala Fizica, 7-10 sept. 2004, Pitesti, Poster
11. T.Beica, R.Moldovan, M.Tintaru, I.Zgura, S.Frunza, G.Burducea “Temperature
dependence of interfacial tension of liquid crystal/glycerol interface”, National Physics
Conference, 7-10 september 2004, Pitesti , Romania, Poster
12. S.Frunza, I.Zgura, M.Tintaru, T.Beica, L.Frunza, A.Schonhals, “Dynamics of
surface layer in nanocomposites cianobiphenyl-aerosil with high silica density ”, CONRO
2004, 7 octombrie 2004, Bucuresti, Romania, Poster
60
13. L.Frunza, “Liquid Crystals confined to nanopors of molecular sieves”, National
Seminar of Nanoscience and Nanotechnology, Bucharest, January 27, 2004, Oral
14. L.Frunza, „Hydrothermal synthesis of some microporous aluminophosphates via the
design of experimental approach”, 1st National Symposium of Engineering and
Nanosciences, Bucharest, 23 April 2004, poster
A. Serghei – PhD student in Physics, Leipzig University, Germany
I. I. Zgura – PhD student in Physics, Faculty of Physics, University Bucharest, Romania
WORK STAGES ABROAD:
1) Dr. L. Frunza (2.5 months) in the Institute of Applied Chemistry, Berlin and Federal
Institute of Materials Research and Testing, Berlin, Germany
2) I. I. Zgura (1 month) training at the Institute of Applied Chemistry, Berlin-Adlershof,
Germany, under Concorde Project
B. GROUP OF OPTICS
HEAD: Dr. IOAN BALTOG
Tel: (+402) 1 493 01 95
Fax: (+402) 1 493 02 67
RESEARCH TEAM:
7
1. Dr. Ioan BALTOG
2. Dr. Mihaela BAIBARAC
3. Lucian MIHUT
4. Timucin VELULA
5. Nicoleta PREDA
6. Marius HUSANU
7. Edit LENGYEL
senior researcher I
assistant researcher*
*Present address: Max-Planck-Institut fur Chemische Physik Fester Stoffe, Lab. High
Pressures, Germany
e-mail: [email protected]
61
Synthesis of hybrid and composite materials based on conducting polymers and various
particles of micrometric and nanometric size and their characterization by studies of
Raman scattering, photoluminescence, photoconductivity and conductivity.
Materials under investigation: conducting polymers, carbon nanoparticles: fullerene (C60)
and single-walled carbon nanotubes (SWNT), micro and nanoparticles of PbI2,
nanostructured composite and hybrid materials.
1.Optical properties of micro- and nanometric size PbI2 particles
By correlated studies of scanning electron microscopy, Raman spectroscopy, optical
absorption and low temperature photoluminescence (PL) we have demonstrate that by the
reaction between Pb(NO3)2 and KI, carried out in different liquids media as water,
methanol, ethanol and acetonitrile, are formed platelets of PbI2 and rods of KPbI3 of
micrometric and nanometric size. Changing the stoichiometry of the synthesis reaction one
modifies the yield of platelets and rods. The formation of two types of particles explains
the great differences between the reported data concerning the shift of the fundamental
absorption edge, of about ten meV and 1.25 eV, as the quantum confinement effects
generated in the low-dimensional systems of PbI2 layered semiconductor compounds.
2. Self-assembling of C60 fullerene in nanometer size clusters
Self-assemblies of C60 fullerene in different solvents or solvent/non solvent mixtures
produced by weak (van der Waals type) and strong (originating in charge transfer) forces
are featured by different SERS and photoluminescence spectra.
3.Covalent functionalization of single-walled carbon nanotubes (SWNTs) by electrochemical polymerization of aniline evidenced by Raman and FTIR spectroscopic studies
Difference between a simple deposition of successive layers of polymer and a covalent
and/or ionic functionalization process is revealed by comparative investigations of the
electropolymerization of aniline both in HCl and H2SO4 solutions on films of C60 fullerene
and SWNTs. A composite of the type polyaniline-leucoemeraldine salt (PANI-LS)
functionalized SWNTs results from the electropolymerization of aniline in HCl solution
on a SWNTs film that by a subsequent treatment with NH4OH transforms in polyanilineemeraldine salt (PANI-ES) functionalized SWNTs composite. The binding of SWNTs as
whole units on the polymer chain induces strong steric hydrance effects observed in FTIR
spectra by the enhancement of bands associated to the deformation vibration of benzenoid
and quinoid ring.
4. Electrochemical oxidation of SWNTs in H2SO4 solution
A quasi-reversible and reversible reaction of oxidation-reduction taking place at SWNT
films/electrolyte (0.5M H2SO4 solution) interface has been demonstrated by surface
enhanced Raman scattering (SERS) spectroscopy and cyclic voltametry performed in the
scanning ranges (0;+100) and (0;+1500)mV, respectively.
5. Photoluminescence and photoconductivitiy studies on PPV/SWNTs composites
62
Photoconductivity of poly(paraphenylene vinylene) (PPV)/SWNTs composites in which
the concentration of SWNTs has varied from 0% to 64% wt. show that the percolation
regim begins at wt.2%.
6. Coherent anti-Stokes Raman scattering on single-walled carbon nanotubes thin films
excited through surface plasmons excitation
Dependence of the anti-Stokes SERS emission on SWNTs film thickness, exciting power
intensity, polarization state of incident and scattered light, numerical aperture of collecting
microscope objective argue the producing of a CARS emission, under one focused beam,
in SWNTs thin films deposited on rough Au support
-Bilateral Cooperation Program (2003-2007) with Institute de Materiaux de Nantes, France
“Etudes spectroscopiques et spectroelectrochimiques des materiaux composites ou
hybrides a base de polymeres conjugues et composes carbones nanostructures”.
-Partner in a Research Training Networks project entitled: Carbon Nanotube
Composites:Towards Strong, Multifunctional and Biosensitive Nanomaterials and
Devices (proposal made in dec 2004)
PAPERS PUBLISHED IN 2004 OR ACCEPTED FOR PUBLISHING
1. M.Baibarac, N.Preda, L.Mihut, I.Baltog, S.Lefrant, J.Y.Mevellec, “On the optical
properties of micro and nanometric size PbI2 particles”, J. Phys: Condensed Matter.16,
2345-2356 (2004)
2. S.Lefrant, M.Baibarac, I.Baltog, J.Y.Mevellec, L.Mihut, O.Chauvet, “SERS
spectroscopy studies on the electrochemical oxidation of single-walled carbon nanotubes
in sulfuric acid solutions”, Synth. Met. 144, 133-142 (2004)
3. L.Mihut, N.Preda, M.Baibarac, I.Baltog, S.Lefrant, J. Wery, “Photoluminescence
studies on [C60] fullerene solutions in N-methyl-2-pyrrolidinone and pyrrolidine”,
Mol.Cryst. Liq.Cryst., 416,13-25 (2004)
4. M.Baibarac, I.Baltog, S.Lefrant, J.Y.Mevellec, O.Chauvet, “SERS spectra of
polyaniline/carbon
nanotubes
and
polyaniline/fullerene
composites”,
Mol.Cryst.Liq.Cryst., 415, 141-155 ( 2004)
5. M.Baibarac, N.Preda , L. Mihut, T.Velula, , I. Baltog, J.Y.Mevellec, S. Lefrant, “C60
aggregates in pyrrolidine and N-methyl-2-pyrrolidinone evidenced by surface enhanced
Raman scattering spectra”, Mol.Cryst. Liq.Cryst., 417,87/[571]-103[587] (2004)
6. S.Lefrant, J.P.Buisson, J.Schreiber, O.Chauvet, M.Baibarac, I.Baltog, “Raman studies
of carbon nanotubes and polymer nanotube composites”, Mol.Cryst. Liq.Cryst., 415, 427434 (2004)
63
7. M.Baibarac, I.Baltog, C.Godon, S.Lefrant, O.Chauvet, “Covalent functionalization of
single-walled carbon nanotubes by aniline electrochemical polymerization”, Carbon, 42,
3143-3152 (2004)
8. E.Mulazzi, R.Perego, H.Aarab, L.Mihut, S.Lefrant, E.Faulques, J.Wery,
“Photoconductivity and optical properties in composites of poly(paraphenylene vinylene)
and single-walled nanotubes”, Physical Review B 70, 155206 (2004)
9. S.Lefrant, J.P.Buisson, J.Schreiber, J.Wery, E.Faulques, O.Chauvet, M.Baibarac,
I.Baltog, “Raman and SERS studies of carbon nanotubes”, Spectroscopy of Emerging
Materials,127-138 (2004)
10. S.Lefrant, M.Baibarac, I.Baltog, T.Velula, J.Y.Mevellec, O.Chauvet,
“Electrochemical and vibrational properties of single-walled carbon nanotubes in
hydrochloric acid solutions”, Diamond and Related Materials (proof, available on line at
www.sciencedirect.com)
11. S.Lefrant, M.Baibarac, I.Baltog, J.Y.Mevellec, C.Godon, O.Chauvet,
“Functionalization of single-walled carbon nanotubes with conducting polymers
evidenced by Raman and FTIR spectroscopy”, Diamond and Related Materials (proof,
available on line at www.sciencedirect.com)
12. S.Lefrant, M.Baibarac, I.Baltog, C.Godon, J.Y.Mevellec, J.Wéry, E.Faulques,
L.Mihut, H.Aarab, O.Chauvet, “SERS, FTIR and photoluminescence studies on singlewalled carbon nanotubes /conducting polymers composites”, Synth. Met. (proof, available
on line at www.sciencedirect.com)
13. M.Baibarac, I.Baltog, S.Lefrant, C.Godon, J.Y.Mevellec, “Mechanico-chemical
interaction of single-walled carbon nanotubes with different host matrices evidenced by
SERS spectroscopy”, Chem Phys Lett (accepted)
CONFERENCES:
1. S.Lefrant, M.Baibarac, I.Baltog, C.Godon, J.Y.Mevellec, O.Chauvet,
“Electrochemical functionalization of single-walled carbon nanotubes with polyaniline
evidenced by Raman and FTIR spectroscopy”, International Winterschools on Electronic
Properties of Novel Materials (IWEPNM), 6-13 March 2004, accepted as poster
2. S.Lefrant, M.Baibarac, I.Baltog, C.Godon, J.Y.Mevellec, J.Wéry, E.Faulques,
L.Mihut, H. Aarab, O.Chauvet, “SERS, FTIR and photoluminescence studies on singlewalled carbon nanotubes / conducting polymers composites”, The International
Conference on Synthetic Metals (ICSM) 2004.The Role and Impact of Nanoscience and
Nanotechnologies Wollongong, New South Wales, Australia, 28 June to 2 July 2004
(accepted as oral conference)
“Functionalization of single-walled carbon nanotubes with conducting polymers
evidenced by Raman and FTIR spectroscopy”, 15th European Conference on Diamond,
64
Diamond-Like Materials, Carbon Nanotubes, Nitrides & Silicon Carbide, 12-17 September
2004,( accepted as oral conference)
4. S.Lefrant, M.Baibarac, I.Baltog, T.Velula, J.Y.Mevellec, O.Chauvet,
“Electrochemical and vibration properties of single-walled carbon nanotubes in
hydrochloric acid solutions”, 15th European Conference on Diamond, Diamond-Like
Materials, Carbon Nanotubes, Ntrides & Silicon Carbide, 12-17 September 2004,
(accepted as poster)
“Electrochemical functionalization of carbon nanotubes with polyaniline evidenced by
Raman and FTIR spectroscopy“, Nanotech & GDR - 2004 , 10-15 oct 2004 ; Blaz – surMer, France, (accepted as oral conference)
Dr. M. Baibarac – Postdoc stage, Institut de Materiaux de Nantes, Lab. Physique
Cristalline, France
E. Lengyel – PhD student in Physics, Max-Planck-Institut fur Chemische Physik Fester
Stoffe, Lab. High Pressures, Germany
N. Preda – PhD student in Chemistry, University Politehnica of Bucharest, Romania
GRANTS AND ABROAD WORK STAGES:
Dr.M.Baibarac - Grant NATO "Nanostructured materials for applications in sensors and
optoelectronic technology"
Dr.I.Baltog (2.01-2.04) as Associate Professor at Institut de Materiaux de Nantes
Dr. M.Baibarac (18.09 -18.10) work stage at Institut de Materiaux de Nantes
L.Mihut (18.09 -18.11) work stage at Institut de Materiaux de Nantes
C. GROUP OF POINT DEFECTS SPECTROSCOPY OF
IONIC CRYSTAL
HEAD : Dr. SILVIU POLOSAN
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
RESEARCH TEAM : 4
1. Dr. Silviu POLOSAN
65
2. Dr. Elena APOSTOL
3. Dr. Monica ENCULESCU
4. Acad. Vladimir TOPA
senior researcher I (guest)
1. Study of negative metallic ions obtained by electrolytic colouring
2. Conversion kinetics of the negative metallic ions in nanoclusters
3. Synthesis and characterization of the silver and gold colloids for medical applications
(suppression of the virus development)
4. Defects obtained by irradiation of pure and heavy metal ions doped alkali halide crystals
5. Synthesis and characterization of the BGO glasses for scintillator detectors
MAIN SCIENTIFIC RESULTS OBTAINED IN 2004
1. The obtaining and characterization of the silver colloids in KCl:Ag, KCl:Ag + Ca and
NaCl:Ag, NaCl:Ag + Ca
The obtaining of the silver nanoclusters embedded in KCl:Ag si NaCl:Ag using
electromagnetic irradiation at RT (X- and γ-ray) and energetic particles (electrons and
alpha beams is reparted). The nanoclusters have been characterized using optical
absorption, TEM and AFM. The silver nanoclusters obtained after alpha beam irradiation
are very similar with those obtained by electrolytical colouring at 600ºC.
2. Silver colloids separation from the crystal and the physical comparison with those
obtained by chemical synthesis
We have successfully separated the silver colloids from the NaCl:Ag monocrystal (the Ag
nanoclusters have been obtained after electrolytical colouring followed by a thermal
treatment at 600ºC for ten days) by dissolving the monocrystal in a aqueous solution of
gelatin 10%. Their physical properties and structure (like optical absorption at about 420440nm and TEM images) are very similar with the case of silver colloids obtained by us
through a chemical synthesis. We have performed several tests for using the colloids for
medical applications (suppression of the virus development) and they were very promising.
3. Defects obtained by heavy ion irradiation in pure and doped alkali halide crystals
Primary defects obtained by heavy ion irradiation of pure and doped alkali halides were
studied, in order to explain the formation of the Frenkel defects and the new defects,
appearing in the crystals which contain metallic colloids during the irradiation. Electron
centres (F-type centres like F2, F3) and hole centres (V-type centres) are obtained by heavy
ion irradiation of pure crystals. The centres concentration is found to be about five times
higher than in the case of LiF crystals.
4. BGO glasses for scintillator detectors
We have obtained Bi2O3∙GeO2 transparency glasses using different conditions. The optical
properties of BGO glasses strongly depends on the history of the samples, especially on the
66
step of the solid state reaction. The emission spectra are quite similarly with the BGO
crystals. We have performed preliminary tests for using as scintilator detector.
- International cooperation with Kyoto University (Prof. Dr. Taiju Tsuboi), Japan.
”Obtaining of Advanced Materials: Complex Spectroscopic Studies of Negative Heavy
Metal Ions in Ionic Crystals”
PAPERS PUBLISHED OR ACCEPTED FOR PUBLICATION IN 2004
1. V.Topa, T.Tsuboi, S.Polosan, “Emission properties of Ta – centres in KCl”, Radiation
Measurements, 38 (4-6), 731-734, (2004)
2. S.Polosan, E.Apostol, M.Secu, G.Aldica, “BGO glasses for scintillation detectors”,
Physica Status Solidi (c), in press
3. E.Apostol, L.Toma, S.Polosan, M.Secu, V.Topa, “Z (Ag-) centres in NaCl:(Ag+ + Ca2+)
crystals”, Physica Status Solidi (c) in press
CONFERENCES :
Proceedings of the “15th International Conference on Defects in Insulating materials
ICDIM-2004, Riga LATVIA”, (2004)
crystals”, Proceedings of the “15th International Conference on Defects in Insulating
materials ICDIM-2004, Riga LATVIA”, (2004)
3. V.Topa, E.Apostol, “New negative heavy metal ions in alkali halides”, Oral
presentation atr the “15th International Conference on Defects in Insulating materials
ICDIM-2004, Riga LATVIA”, (2004)
4. E.Apostol, S.Polosan, M.Nemtanu, C.Oproiu, V.Topa, “Optical studies of electron
beams irradiated KCl:Ag+ and KCl:(Ag+ + Ca2+) monocrystals”, International School on
Radiation Effects in Solids, 17-19 July 2004, Erice-Italy.
D. GROUP OF ORGANIC CRYSTALS.
IONIC CONDUCTIVITY AND ELECTRODIFFUSION
HEAD:
Dr. ANCA STANCULESCU
67
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
RESEARCH TEAM: 3
1. Dr. Anca STANCULESCU
2. Dr. Ionut ENCULESCU*
3. Marcela SOCOL
* Present address: The Ångström Laboratory, Upsala Universitet, Lägerhyddsvägen 1,
Upsala, Suedia, e-mail: [email protected]
Our research activity is focused on molecular organic crystalline materials as bulk and
films (growth, processing and characterization) for optical and electrical applications, on
the optical properties investigation of II-VI semiconductor doped non-crystalline matrix
composite materials and on the preparation of metallic and semiconductor nanowires and
nanotubes using the template method.
1. Study of the effect of dopant on the optical properties of organic molecular films
UV-VIS transmission spectroscopy has been used to investigate the intrinsic properties of
pure meta-dinitrobenzene and pure and doped benzil crystalline films. We have
emphasised the semiconductor behaviour of m-DNB (Eg=2.92 eV) and the two bands split
of the (n, π*) level generating the two edges absorption in benzil (Eg1=2.84 eV and
Eg2=5.55 eV). No significant shift of the absorption peak in benzil situated at 3.25 eV has
been evidenced.
2. Emission spectroscopy study of m-DNB and benzil
The effect of impurities on the shape and position of the emission peaks in benzil films has
been investigated revealing a three steps relaxation process involving the geometrical
change of the (S1) excited state, the intersystem crossing and the radiative decay by
phosphorescence with a peak situated at 2.30 eV, which shift to the blue by heavy doping
with sodium as a consequence of the change in the trans-planar molecular configuration.
The process of self-absorption of emitted radiation in thicker films is responsible for the
red shift of the absorption peak in m-DNB films.
3. Investigation of the optical properties of II-VI semiconductor/glass matrix composite
material
We have analysed the influence of the II-VI semiconductor microcrystallites stoichiometry
and of the glass matrix chemical composition on the optical properties of the
aluminophosphate glass doped with CdSxSe1-x. From the shift of the fundamental
absorption edge we have obtained information on the composition (x) and dimension
68
variations during the growth process. We have emphasised that variations of the annealing
parameters, temperature (425 oC, 450 oC, 475 oC) and duration (2h, 4h, 6h), have generated
changes in the band gap energy between 2.29 eV and 1.74 eV corresponding to a
composition variations between CdS0.94Se0.06 and CdS0.18 Se0.82.
4. Metallic nanotubes prepared using template method
Polycarbonate porous membranes were prepared by etching ion tracks irradiated in the
fluence range of 1 ion per sample to 108 ions per cm2. The membranes were used as
templates for the preparation of tubes based on auto-catalytic copper deposition. A threestep process was used: pre-activation, activation and copper deposition. Copper nucleation
was studied in order to optimize the activation steps thus allowing the preparation of thin
tubes.The external diameters of the tubes ranged from 300 to 2000 nm. The inner diameters
varied as a function of the time-of-exposure to the bath. The length of the tubes was 30µm,
corresponding to the thickness of the foils.
1. A.Stanculescu, F.Stanculescu, M.Socol, "High purity organic functional materials for
crystal growth", Romanian Reports in Physics, 56, 3, 473-480, (2004)
2. A.Stanculescu, S.Antohe, H.V.Alexandru, L.Tugulea, F.Stanculescu, M.Socol "Effect
of dopant on the intrinsec properties of some multifunctional aromatic compounds films
for target applications", Synthetic Metals, 147, 1-3, 215-220, (2004)
3. A.Stanculescu, L.Tugulea, F.Stanculescu, M.Socol, „Fluorescence of aromatic
derivatives crystalline materials for optical non-linear applications”, in ROMOPTO 2003:
Seventh Conference on Optics, edited by V. I. Vlad, Proceedings of SPIE, vol. 5581 (SPIE,
Bellingham, WA, 2004), 600
4. M.E.Toimil Molares, N.Chtanko, T.W.Cornelius, D.Dobrev, I.Enculescu, R.H.Blick,
R.Neumann," Fabrication and contacting of single Bi nanowires ", Nanotechnology 15,
No. 4 S 201- S 207, (2004)
5. M.Sima, I.Enculescu, T.Visan, R.Spohr, C.Trautmann, "Electrochemical deposition of
PbSe1-xTex nanorode and nanotube arrays using track etch membranes as template"
Molecular Crystals and Liquid Crystals, 418, 159-166, (2004)
6. B.Bercu, I.Enculescu, R.Spohr, "Copper tubes prepared by electroless deposition in ion
track templates", Nuclear Inst. and Methods in Physics Research, B, 225/4, 497-502,
(2004)
7. M.Sima, I.Enculescu, C.Trautmann, R.Neumann, "Electrodeposition of CdTe nanorods
in ion track membranes", Journal of Optoelectronics and Advanced Materials, 1, 121-125,
(2004)
8. M.Sima, I.Enculescu, A.Ioncea, T.Visan, C.Trautmann, “Manganese and copper doped
CdS nanowire arrays preparation”, J.Optoelec. and Adv. Mat., 6, 1193-1198, (2004)
69
9. M.Sima, I.Enculescu, T.Visan, “Synthesis of semiconductor nanofibers having
thermoelectric properties by template electrodeposition method”, Revista de chimie
(Bucuresti) 55, 743-747, (2004)
CONFERENCES:
1. A.Stanculescu, S.Antohe, H.V.Alexandru, L.Tugulea, F.Stanculescu, M.Socol (2004):
"Effect of dopant on the intrinsec properties of some multifunctional aromatic compounds
films for target applications", prezentata la European Materials Research Society, E-MRS
2004 Spring Meeting perioada 24-28 Mai, Strasbourg, Franta, sectiunea Supramolecular
Approaches to Organic Electronics and Nanotechnology;
2. A.Stanculescu, L.Tugulea, F.Stanculescu, M.Socol, "Molecular organic crystalline
matrix for hybrid organic-inorganic (nano) composite materials", International Conference
on Crystal Growth, ICCG14, Grenoble, Franta perioada 8-12 August (2004)
3. M.Socol, "Meta-dinitrobenzene crystal growth and characterization ", International
Summer School on Crystal Growth, 1-7 August 2004, Berlin, Germania.
INTERNATIONAL PROJECTS:
„Cadmium Chalcogenites Nanowires”, Marie Curie Actions, European Reintegration Grant
(FP 6), MERG-CT-2004-511020 ; Responsabil Dr. Ligia Frunza, Beneficiar Dr. Ionut
Enculescu
The team has scientific collaboration with Faculty of Physics, University of Bucharest,
especially with students of the 4th year, section Materials Science.
M. Socol is PhD student at the Faculty of Physics, University of Bucharest.
AWARDS:
M. Socol received „Research Student Award” granted by Romanian Materials Science
Crystal Growth Society in recognition of the best paper presented at ROCAM 2003.
E. GROUP OF NANOSTRUCTURATED MATERIALS
HEAD : Dr. MARIAN SIMA
E-mail:[email protected]
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
70
RESEARCH TEAM: 5
1. Dr. Marian SIMA
2. Dr. Victor GHIORDANESCU
3. Dr. Marin NEDELCU
4. Dr. Mihail SECU
5. Dr. Corina SECU
senior researcher III (guest)
researcher
researcher
-
Synthesis, photoluminescence and thermoelectric properties of semiconductor
nanofiber arrays
New rare earth activated materials for “X-ray Digital Radiography” (XDR) for recording images in medical diagnostics and non-destructive testing using PSL (“photostimulated luminescence”) effect: BaX2:RE, (X=Br, Cl, RE=Eu2+, Ce3+).
Detection of the irradiated foodstuff using optical methods, thermoluminescence
and optically stimulated luminescence.
1.Manganese and copper doped CdS nanowires photoluminescence
CdS:Mn2+:Cu+ wires obtained in nano or micropores of polycarbonate membranes present a
luminescence which covers a spectral domain ranging from 500 to 800 nm. EPR data for
Mn2+ ions indicate two different locations, one observed in region of geff=2.0 and one more
at geff=4.3; the last is attributed to magnetically clustered Mn2+ ions. The comparison of the
emission spectra of CdS, CdS:Mn2+, CdS:Mn2+:Cu+ allows establishing the contribution
and interaction between emitting centers. The excitation with 457.9nm Ar laser gives
preponderantly the dopant emissions. The lack of CdS 620nm emission is due to energy
transfer which quenches this luminescence.
2.Preparation of manganese and copper doped CdS nanowires
Manganese and copper doped CdS nanowire arrays were prepared in a two steps process.
In the first step we prepared micro and nanowire arrays of CdMnCu alloy using
potentiostatic deposition in polycarbonate ion track membranes from acid solutions. For
the synthesis of the CdS:Mn2+:Cu+, the metallic alloy was anodized in a solution containing
5x 10-2M Na2S, 1M NaOH, scanning the potential in the range -1.1V to 1.3V/SCE. The
metallic alloy wires participate with the whole surface at the anodization process. The
obtained doped semiconductor nanowires show a nearly stoichiometric composition as
resulted from the EDX measurements.
3. PbTe nanofibers and microtubes
Nanofibers and microtubes of PbTe narrow band semiconductor, having thermoelectric
properties , were prepared by electrochemical deposition into the pores of a polycarbonate
membrane; the electrodeposition was achieved at potential of -0.345V/SCE, using an acid
71
solution. The composition of PbTe nanostructures is : Pb-53.09 at%, Te-46.91 at% (from
EDX measurements).
4. Optical characterisation of the BaX2:RE, (X=Br, Cl, RE=Eu2+,Ce3+)
We have successfully studied the optical properties of RE impurity in the crystals using
photoluminescence and optical absorption techniques and they are showing a high PSL
effect efficiency. These studies are relevant and very useful for the development of the
transparent glass ceramics as a new class of materials for X-ray digital radiography with
higher resolution, in which optically active BaX2:RE, (X=Br, Cl, RE=Eu2+,Ce3+) nanocrystallites (10-100nm) have been found.
Scientific cooperation agreement between Department of Physics, Paderborn University,
Germania and National Institute of Materials Physics,Magurele, Romania:
“Crystalline materials activated with rare earth elements for X-ray Digital Radiography”
PAPERS PUBLISHED OR ACCEPTED FOR PUBLICATION IN 2004:
1. M.Sima, I.Enculescu, T.Visan, R.Spohr, C.Trautmann, "Electrochemical deposition of
PbSe1-xTex nanorode and nanotube arrays using track etch membranes as template",
Molecular Crystals&Liquid Crystals , 418, 21(749)- 27 (755) (2004)
2. M.Sima, I.Enculescu, C.Trautmann, R.Neumann, "Electrodeposition of CdTe nanorods
in ion track membranes" J.Optoelec. and Adv. Mat,. 6, 121-125 (2004)
3. V.Ghiordanescu, M.Sima, I.Enculescu, M.N.Grecu, L.Mihut, M.Secu, R.Neumann,
“Manganese and copper doped CdS nanowires photoluminescence”, Phys. Status Solidi A
(acceptat)
4. M.Sima, I.Enculescu, A.Ioncea, T.Visan, C.Trautmann,“Manganese and copper doped
CdS nanowire arrays preparation”, J.Optoelec. and Adv. Mat. 6, 1193-1198 (2004)
5. C.Valsangiacom, M.Sima, D.Predoi, C.Plapcianu, C.Kuncser, G.Schinteie, M.Bulinski,
“A microscopic analyze of the conduction mechanism of iron doped polyaniline under the
uv exposure”,
Romanian Reports in Physics (acceptat)
6. M.Sima, I.Enculescu, T.Visan, “Synthesis of semiconductor nanofibers having
thermoelectric properties by template electrodeposition method”, Revista de chimie
(Bucuresti) 55, 743-747 (2004)
7. G.Corradi, M.Secu, S.Schweizer, J.M.Spaeth, “Luminescence properties of the X-ray
storage phosphor BaBr2:Ce3+”, Journal of Physics: Condensed Matter 16, 1489-1500
(2004)
72
CONFERENCES :
1. M.Secu, S.Schweizer, U.Rogulis, J.M.Spaeth, A.Edgar, G.V.M.Williams, “Radiation
defects in Ce3+-activated fluorobromozirconate glass-ceramic X-ray storage phosphors”,
Proceedings of the 5th European Conference on Luminescent Detectors and Transformers
of Ionizing Radiation September 1-5, 2003, Prague, Czech Republic, Radiation
Measurements 739-742, 38 (2004)
2. S.Schweizer, M.Secu, J.M.Spaeth, L.W.Hobbs, A.Edgar, G.V.M.Williams, “New
developments in X-ray storage phosphors” Proceedings of the 5th European Conference on
Luminescent Detectors and Transformers of Ionizing Radiation September 1-5, 2003,
Prague, Czech Republic, Radiation Measurements 633-638, 38 (2004)
3. G.Corradi, M.Secu, S.Schweizer, J.M.Spaeth, ““Photoluminescence and
photostimulated luminescence in the X-ray storage phosphor BaBr2 doped with cerium”,
Proceedings of the 5th European Conference on Luminescent Detectors and Transformers
of Ionizing Radiation September 1-5, 2003, Prague, Czech Republic, Radiation
Measurements 511-514, 38 (2004)
4. A.Edgar, GVM.Williams, M.Secu, S.Schweizer, J.M.Spaeth, ““Optical properties of a
high-efficiency glass-ceramic X-ray storage phosphor”, Proceedings of the 5th European
Conference on Luminescent Detectors and Transformers of Ionizing Radiation September
1-5, 2003, Prague, Czech Republic, Radiation Measurements 413-416, 38 (2004)
5. A.Edgar, G.V.M.Williams, J.Hamlin, M.Secu, S.Schweizer, J.M.Spaeth, “New
materials for glass-ceramic X-ray storage phosphors”, Proceedings of the AMN-1 First
International Conference on Advanced Materials and Nanotechnology, 9-14 February
2003, Wellington, New Zealand, Current Applied Physics, 4/2-4, 193-196 (2004)
6. M.Secu, B.Henke, U.Rogulis, S.Schweizer, J.M.Spaeth, “Optical and magneto-optical
studies on Mn-activated LiBaF3”, Proceedings of the “15th International Conference on
Defects in Insulating materials ICDIM-2004, Riga LATVIA”, 2004), Physica Status Solidi
(c)
7. S.Schweizer, M.Secu, J.M.Spaeth A.Edgar, G.V.M.Williams, ““Photostimulable
defects in nano-crystallites in fluorozirconate glasses”, Proceedings of the “15th
International Conference on Defects in Insulating materials ICDIM-2004, Riga LATVIA”,
2004), Physica Status Solidi (c)
Proceedings of the “15th International Conference on Defects in Insulating materials
ICDIM-2004, Riga LATVIA”, 2004, Physica Status Solidi (c)
crystals”, Proceedings of the “15th International Conference on Defects in Insulating
materials ICDIM-2004, Riga LATVIA”, 2004, Physica Status Solidi (c)
73
10. M.Sima, I.Enculescu, R.Neumann T.Visan, C.Trautmann, ”Preparation of
semiconductor nanofiber arrays by template method” (poster), Seminar at Romanian
Academy :“Nanoscience and Nanotechnologie” (27.01.2004)
A grant “Marie Curie Actions European” for Dr M.Secu participation at “15th International
Conference on Defects in Insulating materials ICDIM-2004, Riga LATVIA 11-16 July
2004”
F. GROUP OF ECOLOGICAL SCINTILLATORS WITH MOLECULAR ANIONS
HEAD: Dr. FELICIA IONESCU
Tel: (+4021) 493 01.95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES : 1
RESEARCH TEAM :
1. Dr. Felicia IONESCU
1. L.Ion, S.Antohe, F.Ionescu, “Electron-irradiation effects on CdSe thin films
investigated by thermally stimulated current method”, Journal of Applied Physics, 95, 1,
(2005) (in press)
74
Laboratory of Oxidic Materials
HEAD: Dr. CORNEL MICLEA
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 18
RESEARCH TEAM: 14
1. Dr. Cornel MICLEA
2. Dr. Constantin TANASOIU
3. Dr. Luminita AMARANDE
4. Dr. Igor NAZARENCO
5. Dr. Alin IUGA
6. Corneliu Florin MICLEA*
7. Lucian TRUPINA
8. Elena Daniela ION**
9. Marius CIOANGHER
10. Nicolae Felix SIMA
11. Vasilica TOMA
12. Gica BRADULET
senior researcher I
senior researcher I
researcher
researcher
* Present address: Max Planck Institute for Solid State Physics, Dresden, Germany, on
leave for PhD.
** Present address: Jozef Stefan Institute, Ljubljana, Slovenija, on leave for PhD.
1. Nanostructured semiconducting oxidic materials based on doped barium titanate for
thermal sensors
Our scientific efforts have been directed towards developing new doped based barium
titanate (BT) materials with special properties capable to be used as heating elements when
working at higher voltages. The main goal is to find the ideal additives which may conduct
to an ideal heating source in which the temperature remains constant while its power
dissipation is automatically adapted to thermal load. The main features of such novel
elements consist in a practically infinite lifetime, a considerable energy saving, a maximum
safety since there is no incandescent heating, maintenance of a constant temperature and so
on.
Our studies concerning this project are focused on finding the right additive for BT and the
corresponding way for processing them. In this regard we have studied the effect of Sr, Ca,
Y, Nb, La and Si, additives on the structural and electrical properties of the basic
compounds. At the same time we have elaborated the technology to obtain high quality
ceramics based on doped BT. The parameters considered during investigation were:
composition, pressing pressure, heating and cooling rate, temperature and time. The
preliminary results showed that by a corresponding doping the resistivity at room
temperature is generally situated between 10 and 100 Ω·cm, the PTC effect is very high
(around 3 to 4 order of magnitude) and the PTC temperature is around 150 oC.
75
2. Study of nanostructured piezoceramic materials obtained by conventional and
nonconventional technologies.
Our concern has been concentrated on the effect of some isovalent and acceptor dopants
such as Ba, Sr, for A positions and transitional elements such as Ni, Fe, Zn, Mn, Mg etc.
for B positions in the perovskitic lattice. The most interested results obtained were with Sr,
Ba, Ni, Fe and Mn and a number of such doped ceramics were carefully investigated.
We developed a mechanical activation method to prepare multicomponent piezoceramic
materials, and succeeded in obtaining high quality material by this novel advanced route. It
consists in mixing up the stoichiometric oxidic components in a high energy ball mill for a
prolonged time (tens of hours) by taking care to the balls/powder ratio and mill energy. In
this procedure the synthesis reaction between the elemental components is triggered
automatically during milling by local heat and pressure created by the impact of balls and
wall vials. The powders obtained by this procedure are always nanometric so that by using
this technique we prepared and investigated a number of nanostructured PZT type materials
of high quality.
3. Study of nanostructured piezoceramic materials obtained by conventional and PZT
massive target for R. F. sputtered thin films
Using both conventional and nonconventional (chemical and mechanical activation)
techniques we have prepared a number of large targets to be used for RF sputtering of PZT
thin films. The targets were prepared from calcined as well as from nanostructurated
powders by pressing disc shaped samples of 40 and 50 mm diameter (various thicknesses)
and sintered them at temperatures of 1200-1250 oC The structure and homogeneity of the
targets were checked by SEM micrographs and the results were quite satisfactory.
Preliminary results for RF sputtered thin films showed good quality films.
4. Study of magnetic oxidic materials in the system CuZnTiFe, with highly sensitive
properties on temperature
We have investigated a soft type magnetic material in the system CuZnTiFe, with the
chemical formula Cu1-xZnxTiyFe2-yO4, which have been prepared by the usual ceramic
technique from pure oxides, mixed and then calcined at 1100 oC. Ring shaped pressed
samples were chosen for the study, which were sintered at different temperatures and
cooled down from the sintering temperature in three ways: slow, rapid and quenched. The
best results were obtained for rapid cooled samples where the µ(T) slope was the highest
(52%/oC) such materials are extremely useful for practical applications. Slow cooling and
quenching gave rather low µ(T) slopes and cannot be used as sensitive temperature
transducers. Curie temperature can be easily altered by a fine control of composition. Thus
we have found a nearly linear dependence of TC on the amount of Zn and Ti, the slope
being almost 10-12 oC/at% of dopant.
Using the composition with a given TC and a highest µ(T) slope, a sophisticated
minithermostat is designed which was able to maintain the temperature inside it within
±0.1 mK around thermostating value for a long time.
5. New and advanced procedures for PZT type material processing
The necessity for homogeneous and nanostructured piezoceramic materials for special
application such as biomedical sensors and transducers for piezoelectric motors has
conducted to new approaches in preparing and processing such materials. A new technique
76
adopted for preparing nanopowders is mechanochemical activation method in which the
solid state reaction between the components takes place by the combined effect of
temperature and pressure at the impact contact between the ball, or balls, of an energy
milling mill and the vial walls in which the mixing is done. We successfully used this
technique to prepare some usual PZT materials. It is worth noting here that in this
procedure there is no need to calcine the mixed components, since the reaction is triggered
randomly in some places where nuclei of the new material are formed and progressively
increases to form tiny monocrystals. The powder obtained by this procedure proved to be
more reactive and good quality ceramics were formed at lower sintering temperatures
comparing with the conventional method.
6. PT type piezoceramic materials with electromechanical anisotropy for directional
transducers
Lead titanate (PT) ceramics represent a material with high Curie temperature and rather
low dielectric constant. Using corresponding dopants, the modified PT ceramics with
desired properties can be produced. In our studies on this material we used Bi, Y and Ni
dopants to improve the properties and mainly the electromechanical anisotropy. The effect
of Bi and Y was a stability of tetragonality to reasonable values and an anisotropy of
electromechanical factors of about 10 (ratio of kt and kp) at room temperature. The presence
of Ni was even more beneficial and it increased the kt/kp ratios up to 100 around room
temperature, due to the decrease of kp nearly zero.
7. Electronic components based an optoelectronic switches
The main objective of this project was the study of semiconducting chalcogenides based on
nonstoichiometric Cr2O3, in order to develope new optoelectronic switches. The results
obtained so far include: optimization of the raw chalcogenides used for photoresistances
sensitive in green and orange spectra and the production of such photo resistances by
sintero-sublimation technique. The researches in this field are running further to obtain
high quality photoresistances at mass scale production.
AWARDS:
Our research activity, scientific works and products were exhibited at the International
Trade TIB-2004 and at the Special Exhibition MADE IN ROMANIA (CONRO 2004),
Bucharest, Romania.
The exhibited products were:
1) Piezoceramic materials for active elements;
2) Ultrasonic transducers with various active piezoceramic elements;
3) High power US transducers for preventing calcareous depositions in heat
exchangers;
4) NTC and PTC Thermistors for temperature measurements and control;
5) Magnetic materials for high sensivity temperature sensors;
Our contribution to this exhibition was awarded with the EXCELENCE DIPLOMA.
INTERNATIONAL COOPERATION & PROJECTS
77
1. POLECER “European Thematic Network on Polar Electroceramics” 2001-2006, Dr.
Cornel Miclea
2. COST 525, "Advanced electroceramics: grain boundary engineering" , 2004-2005, Dr.
Cornel Miclea
3. CONCORDE, 2004-2005, Dr. Cornel Miclea
4 Project title: “Hydrostatic pressure cells for measurements at high pressure and low
temperature” - 2004-2005; Partner: The High Pressure Department of the Max Planck
Institute for Chemical Physics of Solids, Dresden, Germany
EDUCATIONAL ACTIVITIES
A. PhD THESIS:
PhD Thesis in preparations
Iuliana Radu
Ion Elena Daniela
Voicu Ionel
David Cristina
Sima Nicolae Felix
Lucian Trupina
Liliana Popescu
B. SCOLARSHIPS ABROAD :
1. – Sima Nicolae Felix, 6 months at Institut National des Sciences Appliquees de
Strasbourg, France (Grant ERASMUS and PHARE)
2. - Corneliu Florin Miclea, Scolarship and PhD at Max Planck Institute for
Chemical Physics of Solids, Dresden, Germany
3. - Ion Elena Daniela, Scolarship and PhD at Stefan Jozef Institute, Dept of
Electronic Ceramics, Liubliana, Slovenia
C. MASTER:
1. Nicolae Felix SIMA-Master in Physics Courses at the Physics Faculty, Bucharest
University, October 2003- February 2005
PUBLICATIONS:
1. C.F.Miclea, H.D.Hochheimer, P.K.Dorhout, B.Martin, G.Sparn, “Interplay between
superconductivity and charge density wave instability in TlxV6S8”, J. Mag. Mag. Mat, 272276, 675-677 (2004)
2. C.Miclea, C.Tanasoiu, A.Gheorghiu, C.F.Miclea, “Synthesis and piezoelectric
properties of nanocrystalline PZT-based ceramics prepared by high energy ball milling
process”, J. Mat. Sci., 39, 5431-5434 (2004)
78
3. C.Miclea, L.Amarande, C.Tanasoiu, C.F.Miclea, V.Sandu, A.Gheorghiu, “Effect of
ytrium substitution on the structure and piezoelectric properties of lead titanate ceramics”,
IEEE Electron Devices, 2, 411-414 (2004)
4. R.Ramer, E.Dimitriu, L.Boerasu, A.Iuga, “Microanalysis
piezoceramics”, Key. Eng. Mat., 264-268, 1173-1176 (2004)
of
Pb(ZrWLi)O3
5. C.Miclea, C.Tanasoiu, C.F.Miclea, A.Gheorghiu, “Effect of lead titanate-zirconate
additions into barium titanate ceramics on the dielectric and piezoelectric properties of
mixed compounds”, Ferroelectrics (in press 2004)
6. C.Miclea, C.D.Comeaga, C.Tanasoiu, C.F.Miclea, A.Gheorghiu, L.Amarande,
M.Cioangher, “Moiré deflectometry measuring method for nonlinear deformation
measurement of piezoelectric bimorph type transducers”, Proceedings International
Conference “Material, Technology and Design of Integrated Piezoelectric Devices”,
Courmayeur, Italy, February 1-4, (2004)
7. C.Miclea, A.Gheorghiu, C.Tanasoiu, C.F.Miclea, V.Tanasoiu, “Effect of
conventionally and fast sinterings on the piezoelectric properties of PZT type ceramics”,
J.Europ.Cer.Soc (in press 2004)
8. C.Miclea, C.Tanasoiu, C.F.Miclea, A.Gheorghiu, V.Tanasoiu, F.N.Sima, “Effect of
iron and nickel substitution on the piezoelectric properties of PZT type ceramics”,
J.Europ.Cer.Soc.(in press 2004)
9. C.Miclea, C.Tanasoiu, C.F.Miclea, A.Gheorghiu, V.Tanasoiu, “Soft ferrite materials
for magnetic temperature transducers and applications”, JMMM (in press 2004)
10. C.Miclea, C.Tanasoiu, C.F.Miclea, “Effect of lead titanate-zirconate additions into
barium titanate ceramics on the dielectric and piezoelectric properties of mixed
compounds”, J. Mat. Sci. (in press 2004)
11.C.F.Miclea, H.D.Hochheimer, B.Martin, P.K.Dorhout, G.Sparn, “Non Fermi Liquid
behaviour and FFLO transition in CeCoIn5”, J. Phys. Condens. Matter (in press 2004)
CONFERENCES
1. C.Miclea, C.D.Comeaga, C.Tanasoiu, C.F.Miclea, A.Gheorghiu, L.Amarande, M.
Cioangher, Moiré deflectometry measuring method for nonlinear deformation
measurement of piezoelectric bimorph type transducers, International Conference
“Material, Technology and Design of Integrated Piezoelectric Devices”, Courmayeur, Italy,
February 1-4, (2004)
2. C.Miclea, C.Tanasoiu, C.F.Miclea, M.Cioangher, “Piezoceramic ultrasonic
transducer for preventing the calcarous depositions on the inner walls of heat
exchangers”, International Workshop «See Tomorow Today», Hanover, Germany, 19-25
April (2004)
79
3. C.Miclea, L.Amarande, C.Tanasoiu, C.F.Miclea, A.Gheorghiu, “Effect of iron and
nickel substitution on the piezoelectric properties of PZT type ceramics”, International
Conference ELECTROCERAMICS IX, Cherbourg, France, May 31 – June 03 (2004)
4. C.Miclea, L.Amarande, C.Tanasoiu, C.F.Miclea, “Mechanochemical synthesis of
nanostructured complex perovskites”, CONCORDE Workshop “Nanostructured Oxide
Catalysts Prepared by Non-conventional Methods and Their Characterization”, Valencia,
Spain, 4-5 June 2004
5. C.Miclea, C.Tanasoiu, C.F.Miclea, A.Gheorghiu, “Soft ferrite materials for magnetic
temperature transducers and applications”, International Conference, JEMS'04Joint European Magnetic Symposia, Dresden, Germany, September 02-06 (2004)
6. C.Miclea, C.Tanasoiu, C.F.Miclea, A.Gheorghiu, “Effect of lead titanate-zirconate
additions into barium titanate ceramics on the dielectric and piezoelectric properties of
mixed compounds”, “7th European Conference on Applications of Polar Dielectrics ECAPD-7”, Liberec, Czech Republic, September 6-9, 2004
7. C.F.Miclea, H.D.Hochheimer, B.Martin, P.K.Dorhout, G.Sparn, “Coexistence and
competition of superconductivity and charge density wave instability in TlxV6S8”,
International Conference ICM/SCES, Rome, Italy, 2004
8. I.Nazarenco, B.A.Sava, A.Meghea, R.Mihalache, D.Ulieru, “A combined sinteringsublimation method to grow light responsive polycrystalline thin films”, 8th International
Conference “Polymers and Advanced Materials”, Cancun, Mexico (2004)
9. C.Miclea, L.Amarande, C.Tanasoiu, C.F.Miclea, A.Gheorghiu, “Effect of ytrium
substitution on the structure and piezoelectric properties of lead titanate ceramics”,
International Semiconductor Conference CAS 2004, Sinaia, Romania, October 4-6 (2004)
10. C.Miclea, L.Amarande, C.Tanasoiu, M.Cioangher, N.F.Sima, “Materiale
semiconductoare oxidice nanostructurate pe baza de titanat de bariu dopat pentru senzori
termosensibili”, 5th National Simposium MATNANTECH, Sinaia, Romania, October, 27–
31 (2004)
11. C.Miclea, L.Amarande, C.Tanasoiu, C.F.Miclea, “Materiale piezoceramice
nanostructurate”, 5th National Simposium MATNANTECH, Sinaia, Romania, October
27–31 (2004)
12. I.Nazarenco, J.Jaklovzsky, I.Albeanu, M.Dumitrescu, “Photoelectric sensors with
self-contained or remote amplifiers, limit-switch style or miniature housings,using A2 B6:
Cr2O3 photoconducting detectors”, Physics National Conference, Pitesti, Romania (2004)
80
NATIONAL INSTITUTE OF MATERIALS PHYSICS*ANNUAL REPORT 2004
Laboratory of Structure and Dynamics of Condensed Matter
HEAD: Dr. DIAMANDESCU LUCIAN
Dr. SERBAN CONSTANTINESCU
Tel.: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 19
RESEARCH TEAM: 16
A.
GROUP OF PHYSICS OF TRANSITIVE PHENOMENA &
MÖSSBAUER SPECTROSCOPY
HEAD: Dr. DIAMANDESCU LUCIAN
Tel.: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 10
RESEARCH TEAM: 8
1.
2.
3.
4.
5.
6.
7.
8.
Dr. Lucian DIAMANDESCU
Dr. Ing. Ion BIBICU
Dr. Mircea ROGALSKI1
Dr. Serban CONSTANTINESCU
Dr. Doina TARABASANU-MIHAILA
Dr. Marcel FEDER
Drd. Alina BANUTA
Drd. Dragos CONSTANTIN2
senior researcher I
senior researcher I
senior researcher I
1
Actual address: Instituto Superior Tecnico, Lisabona, PORTUGAL
Actual address: University of Maryland, Physics Department, Maryland, College Park,
MD 20742 USA
2
1.
2.
3.
4.
5.
6.
Synthesis and characterization of new physical structures.
Oxides: solvothermal versus mechano-chemical synthesis and mechanisms.
New ceramic magnetic materials for high frequency applications.
Investigation and modeling-computation of local electric and magnetic crystal fields in
static-disorder crystalline media (synthetic or natural samples).
Mineral crystal-chemistry, ceramics and sediment dating.
Advanced materials structural modifications induced by irradiation.
81
1. Oxides: unconventional synthesis, structural studies and applications
- α-Fe2O3-In2O3 mixed oxide nanoparticles system has been synthesized by hydrothermal
supercritical and post annealing route, starting with an aqueous solution of iron (III) nitrate
nanohydrate and indium (III) nitrate pentahydrate. X-ray diffraction and Mössbauer
spectroscopy have been used to study the phase structure and substitutions in these samples.
It was found that a corundum like phase α-(Fe1-xInx)2O3, isostructural with α-Fe2O3, exists for
0≤x≤0.9 and a cubic like phase c-(Fe1-xInx)2O3, isostructural with In2O3, exists for 0.3≤x≤1 in
the hydrothermal system, where x is the nominal molar indium concentration. The solubility
limits of In3+ ions in hematite lattice and the solubility limits of Fe3+ ions in the cubic In2O3
structure have been determined. An explanation of the processes leading to the formation of
iron and indium phases in the investigated supercritical hydrothermal system has been given
(J. Phys. Chem. Sol., 65, 1719-1725, 2004).
- NiZn and Zn nanoferrite films were obtained by laser ablation deposition on
Si
substrates. X-ray diffraction patterns, hysteresis loops and magnetization curves samples
show that the magnetic properties of the films are in many respects similar to those of the
bulk, which makes the laser ablation deposited ferrite films prime candidates for thin-film
high-frequency microwave device applications (MMM Conf. Florida USA 2004, in press
J. Appl. Phys).- Fe3O4 film has been obtained and its half-metallic properties were investigated for use in
spintronic devices (Materials Sci. Eng. B (accepted)).
2. Mössbauer spectroscopy applications
- Samples of Fe3-xMnxO4 (x=0-0.6) were studied at and below the Verwey transition
(T=122, 77 and 4.2 K) by 57Fe Mössbauer spectroscopy. Considering that Mn2+ substitutes
for Fe2+ on octahedral sites, we inferred the existence of five subspectra at all temperatures,
one for Fe3+ ions on tetrahedral sites, two for Fe3+ ions on octahedral sites, and two for Fe2+
ions on octahedral sites. The hyperfine fields of one Fe3+ sublattice and two Fe2+ sublattices
decrease slightly with increasing the amount x of Mn substitutions. The results are
consistent with the existence of localized octahedral Fe3+ and Fe2+ spin states below the
Verwey temperature (Mat. Lett., 58, 6, 885-888, 2004).
- A pressure-temperature diagram of solid state (metamorphic) transformation of Razoare
mineral assemblage (Preluca Mts.) have been proposed taking into account the refined and
combined analysis of Mn-Fe minerals by Mössbauer and electron microscopy techniques
(Rom. J. Phys. 49, 7-8, 2004; Proceedings of 5th International Symposium on Eastern
Mediterranean Geology, Thessaloniki, Greece, 14-20 April 2004, vol. 3, 1110-1113, ed.
Chatzipetros A.A. & Pavlides S.B., oral presentation).
- The experimental dispersion of the electric and magnetic hyperfine fields has been
inspected by 151Eu and 57Fe Mössbauer spectroscopy, in static-disorder crystaline media of
iron-rare earth gallogermanate and gallosilicate structures. Correlation between the
intensities of hyperfine fields and the cationic ccupancies in such structures has been
extracted, (accepted in Rom. Rep. Phys. 56, 7-8,2004)
82
- Project title: Solvothermal elaboration and the study of physical properties of some
substitute oxide structures (2002-2006);Partner: Physics Department Duquesne University,
Pittsburgh, USA
- Project title: Measurements and characterization of some iron oxide compounds by
Mössbauer spectroscopy ; Partner: Physics Department, Instituto Superior Tecnico, Av.
Rovisco Pais 1040-001 Lisbon Portugal
1. I.Bibicu, A.Samide, M.Preda, “Steel corrosion in diluted ammoniac solutions studied by
Mössbauer spectrometry”, Mat. Lett. 58, 21, 2650-2653, (2004)
2. M.Sorescu, L.Diamandescu, D.Tarabasanu-Mihaila, “α-Fe2O3 - In2O3 mixed oxide
nanoparticles synthesized under hydrothermal supercritical conditions”, J. Phys. Chem.
Sol. 65, 1719-1725, (2004)
3. M.Sorescu, L.Diamandescu, A.Grabias, “Pulsed laser deposition of nanocomposite αFe/Nd2Fe14B magnets”, J. Mat. Sci., 39, 6121-6123, (2004)
4. M.Sorescu, L.Diamandescu, M.Valeanu, A.Jianu,“Effect of Cobalt substitutions in
spring magnets”, J. Mat. Sci., 39, 7387-7389, (2004)
5. M.Sorescu, L.Diamandescu, R.Peelamedu, R.Roy, P.Yadoji, “Structural and magnetic
properties of NiZn ferrites prepared by microwave sintering”, J. Magn. Magnetic
Materials, 279, 2-3, 195-201, (2004)
6. M.Sorescu, L.Diamandescu, D.Tarabasanu-Mihaila, V.S.Teodorescu, B.H.Howard,
“Hydrothermal synthesis and structural characterization of
(1-x)α-Fe2O3–xSnO2
nanoparticles”,J.Phys.Chem.Solids,65,5,1021-1029,(2004)
7. M.Sorescu, L.Diamandescu, R.A.Brand, D.Tarabasanu-Mihaila, “Mossbauer study
of manganese-doped magnetite below the Verwey transition”, Mater. Let. 58 (6) 885-888,
(2004)
9. M.Sorescu, L.Diamandescu, A.Grabias, “Evolution of phases during mechanochemical
activation in magnetite-containing systems”, Mater. Chem. Phys. 83 (2-3): 354-360,
(2004)
10.
M.Sorescu,
L.Diamandescu,
D.Tarabasanu-Mihaila,
V.S.Teodorescu,
“Nanocrystalline rhombohedral In2O3 synthesized by hydrothermal and postannealing
pathways”, J. Mater. Sci. 39 (2): 675-677, (2004)
11. R.Olar, M.Badea, L.Diamandescu, E.Cristurean, D.Marinescu, D.TarabasanuMihaila, N.Stanica, M.Brezeanu, “Soft chemical synthesis and characterisation of some
substituted ferrites”, J. Alloy Comp. 363 (1-2): 257-262, (2004)
83
12. M.Sorescu, L.Diamandescu, D.Tarabasanu-Mihaila, ”Recoilless fraction on tindoped hematite nanoparticles obtained by hydrothermal synthesis”, (Accepted, Mat. Lett.
2004)
13. A.Samide, I.Bibicu, M.Rogalski, M.Preda,“A study of the corrosion inhibition of
carbon-steel in diluted ammonia media using 2- mercapto-benzothiazol (MBT) by
Mössbauer spectrometry”, Acta Chim. Slovenica 51, 127-136, (2004)
14. A.Samide, I.Bibicu, M.Rogalski, M.Preda, “Surface study of the corrosion of carbon
steel in solutions of ammonium salts using Mössbauer spectrometry”, J. Radioanal. Nucl.
Chem. 261, (3), 593-596, (2004)
15. M.L.Paramês, J.Mariano, N.Popovici, M.S.Rogalski, O.Conde, “UV pulsed laser
deposition of magnetite thin films” , Materials Sci. Eng. B (accepted)
16. O.Caltun, M.Feder, C.J.Liu,“Polycristalline Ni, Zn and Ni-Zn ferrite targets for
plasma laser deposition technique”, J. Optoel. Adv. Mat., 6(3) 955-958, (2004)
17. A.Samide, I.Bibicu, M.S.Rogalski, M.Preda “Surface study of the corrosion
inhibition of carbon steel in diluted ammonia media using N-ciclohexil-benzothiazolesulphenamida”
(Accepted, Corrosion Science, 2004)
18. S.Constantinescu, “Mössbauer investigation of static-disorder crystalline media.
I.57Fe NGR spectra on tetragonal and trigonal gallogermanate", Rom. Rep. Phys., 56, 1,
57-69, (2004)
19. S.Constantinescu, “Mössbauer investigation of static-disorder crystalline media.II.
Crystal-chemistry aspects of tetragonal and trigonal germanates (gehlenite and gallate
structures)”, Rom. Rep. Phys., 56, 1, 71-86, (2004)
20. G.Udubasa, S.Constantinescu, S.Calogero, “Mössbauer investigation of some
Romanian pyrite samples of different genesis”, Proc. of Rom. Acad. B, 5, 3, 141-145,
(2004)
21. S.Constantinescu, ”Mössbauer investigation of static-disorder crystalline media.III.
Dispersion of electric and magnetic hyperfine fields in static-disorder crystalline media”,
Accepted, Rom. Rep. Phys. (2004)
22.
S.Constantinescu,
N.Popescu-Pogrion,
G.Udubasa,
P.Hartopanu,
S.T.Redfern,“Structural investigation of fayalite-tephroite series from Razoare Mn-Fe
ores deposit, Romania”, Accepted, Rom. Journal Phys. 49, 7-8, (2004)
23. S.Constantinescu, I.Gheorghe, C.Stoicescu, S.Georgescu, O.Toma, I.Bibicu, “Growth
and XRD, optical and Mossbauer investigations of Eu doped trigonal La - Gallosilicate
crystal”, Rom. Rep. Phys (accepted vol. 56, nr. 4, 2004)
BOOKS:
M. S. Rogalski, S. B. Palmer
84
Advanced University Physics, 2nd Edition (2005)
CONFERENCES:
1. S.Constantinescu, G.Udubasa, N.Popescu-Pogrion, “Some iron silicate of Romanian
deposits investigated by Mössbauer effect”, Proceedings of 5th International Symposium
on Eastern Mediterranean Geology, Thessaloniki, Greece, 14-20 April 2004, vol. 3, 11101113, ed. Chatzipetros A.A. & Pavlides S.B., (oral presentation)
2. M.Sorescu, L.Diamandescu, R.Swaminathan, M.E.McHenry, M.Feder, “Structural
and magnetic properties of NiZn and Zn ferrite thin films obtained by laser ablation
deposition” MMM Conf. Florida, SUA, nov. 2004 published by J. Appl. Phys.
3. R.Swaminathan, M.E.McHenry, M.Sorescu, L.Diamandescu, S.Calvin, “Surface
structure model for cuboctahedrally truncated ferrite nanoparticles”, International
Conference (ICF-9) on Ferrites, San Francisco 2004 (submitted to Journal of American
Ceramic Society)
4. C.Munteanu, M.Crata, M.Feder, M.Caldararu, L.Diamandescu, J.Kovacs, N.Ionescu,
A.Redey, “Propane oxidation on iron-containing compounds”, 13th International Congress
on Catalysis, Paris, 11-16 July, P6-126, p.317, (2004)
5. V.S.Teodorescu, M.G.Blanchin, M.Sorescu, L.Diamandescu, D.Tarabasanu-Mihaila,
“Structure of iron – tin mixed nanoparticles”, ICPAM-7, 2004, Iasi, Romania
“HRTEM studies of (1-x)α-Fe2O3 - xSnO2 nanoparticles”, EMC 2004 Thirteenth European
Microscopy Congress, University of Antwerp, Belgium, August 22 - 27, (2004)
7. A.Tomescu, R.Roescu, I.Dumitriu, D.Tarabasanu-Mihaila, L.Diamandescu, ”Gas
sensing properties of mixed alpha Fe2O3 – SnO2 nanoparticles prepared under
hydrothermal conditions”, Proceedings of International Conference CAS Sinaia 2004. p.
109-112
8. I.Bibicu, “Mössbauer spectroscopy applied to surfaces and interfaces”, Simpozionul
National CNCSIS de Inginerie si Nanostiinte, UPB, Bucuresti, , 23 Aprile 2004
9. L.Diamandescu, D.Tarabasanu-Mihaila, V.S.Teodorescu, A.Tomescu, R.Roescu,
“Hydrothermal synthesis and structural characterization of (1- x) α-Fe2O3–xSnO2
nanoparticles”, Seminarul National ROMNET-ERA” Nanostiinta si Nanotehnologie ”
Bucuresti (2004)
10. A.Samide, I.Bibicu, B.Tutunaru, M.Preda, “Studiul suprafetei otelului carbon corodat
in ape industriale care contin NH3/saruri de amoniu utilizand spectrometria Mösbauer”,
Conferinta Nationala de Chimie, Caciulata – Ramnicu Valcea, Abstracts Volume, p.382 68 octombrie (2004)
11. S.Constantinescu, N.Popescu-Pogrion, “ The influence of antiferromagnetic clusters
on TCR of thin NiCr films” , poster, Book 2, Poster Sessions, ICV-16, ICSS-12, NANO-8,
Venezia, may 2004
85
12. B.Munteanu, M.Carata, M.Feder, M.Caldararu, L.Diamandescu, J.Kovacs,
N.I.Ionescu, A.Redey, ”Iron oxides based composites as catalysts in deep propane
oxidation”, Al VII lea Simpozion de Cataliza, , Bucuresti, Oct. 7-8, 2004, Abstract
volume pg.43
13.
M.Feder,
D.Mihaila
Tarabasanu,
I.Bibicu,
V.S.Teodorescu,
L.Diamandescu, “ Sinteza si caracterizarea α-LiFeO2 nanocristalin “, Simpozionul
International “Cercetarea stiintifica – o punte spre integrarea europeana”, Universitatea
"Aurel Vlaicu" Arad, 3-4 Noiembrie 2004; Analele Univ. Arad. Seria Chimie, Fascicola
Chimie si Protectia Mediului, p. 56-63
14. M.Tirnovan,
R.Bercia,
S.Constantinescu, N.Popescu-Pogrion,“Mathematical
packing models of low Y doped α-Al2O3”Proc. 4th International Workshop Materials for
Electrotechnics”, Bucharest, May 2004 p. 448 – 452
B: GROUP OF ELECTRON MICROSCOPY, X-RAY AND NEUTRON
DIFFRACTION
HEAD: Dr. FLORIN VASILIU
Tel.: (+4021) 493 01 95
Fax: (+4021) 493 02 67
RESEARCH TEAM:
1.
2.
3.
4.
5.
6.
7.
8.
Dr. Florin VASILIU
Dr. Nicolae POPA1
Dr. Nicoleta POPESCU-POGRION
Dr. Corneliu SARBU
Liviu DUMITRACHE
Gabriela ALEXE2
Manuela STIR3
Ionel MERCIONIU
researcher
senior researcher I
senior researcher I
assistant
1
Actual address: Joint Institute for Nuclear Research, Lab. Neutron Physics, Dubna,
RUSSIA
2
Actual address: Ph. D fellowship at Bremen University, GERMANY
3
Actual address: Ph.D fellowship at Rostock University, GERMANY
PRESENT RESEARCH INTEREST
1. Ferroelectric layers
2. Advanced ceramics
3. Investigation of material microstructure by X-ray and neutron powder diffraction.
86
1. NRBS, RBS, TEM and SAED characterisation of sol-gel PZT films
TEM-SAED investigations were performed on PZT films, to elucidate the role of pyrolysis
conditions on orientation selection. For short pyrolysis, occurrence of the metastable
fluorite and the interfacial PtxPb template layer are the factors inducing the (111) PZT
orientation. For advanced pyrolysis the TiO2 interfacial layer could be responsible for (100)
PZT strong orientation. To further investigate the stoichiometry of PZT and interfacial
layers, we performed heavy ion RBS and NRBS measurements. Only a substoichiometric
TiO2-x layer is found for the short pyrolized film whereas two Ti and O rich layers were
observed for advanced pyrolysis. The thicker oxygen rich TiO2-x bottom layer, observed by
TEM and NRBS analysis, could lead to <100> texture, observed for oxidizing conditions at
the interface during pyrolysis (Nucl. Instr. Meth. B, 2005 , in press)
2. Correlation between the porosity and the grains growth in low Y doped alpha-alumina.
Mathematical model for low porosity
Dopant yttrium at 150 p.m level (Y to Al atomic ratio) in ultra –high purity polycrystalline
alumina has been found to be, together with the coefficient of porosity, the reason of grain
growth: with abnormal grain growth (AGG) or with uniform grains. Microstructural
inhomogeneities of the Al2O3 samples influence inter allia microhardness, thermal
diffusion, refractive index. The characterisation of low Y doped α-Al2O3 powder materials
used for the preparation of green body and sintered compact is one of the basic conditions
to achieve the final desired properties. The shape, average size and homogeneity of the
particles determine the structural characteristics of compact samples such as: shape of
grains, grain boundaries, surface and interfaces, porosity, phase separation. By
mathematical modelling and electron microscopy investigations (SEM, TEM, HRTEM) the
correlation between the powders, green bodies and sintering compacts has been obtained in
real space R3.
The contribution of porosity in the evolution and development of the grains (especially in
the development of the abnormal grain growth AGG) was evidenced. A new mode of
growth was revealed for low porosity materials also by correlation between structural
investigations and mathematical modelling (J. Optoelectronics and Advanced Materials,
Vol.6, No.3, 1071-1075, 2004).
3. Role of the interlayer and the epitaxial stage on the structure of PZT /IrO2 electrodes
The morphology of the PZT grains and the orientation of grains as a function of size were
determined. TEM (SAED), HRTEM, XRD investigations revealed the presence of a
polycrystalline Ir3Ti layer at the interface PZT/IrO2. The epitaxial growth along (101) or
(110) PZT planes on the (110) IrO2 was evidenced.
The grain morphology of the sol-gel PZT films, the size of the grains, the dependence
between the orientation and the size of the grains, the uniformity of the layers, the
morphology of the grain boundaries in plan view and in cross-section view, the
morphology and the identification of the interlayers between PZT and IrO2 were revealed.
87
The grain size has a dominant effect in the orientation of the grains (J. Optoelectronics and
Advanced Materials, Vol.6, No.3, 1055-1058, 2004).
4. Novel plasticity properties of ceramic materials at low temperatures
A surprising result concerning the plasticity of SrTiO3, an oxide ceramic material hitherto
believed to be extremely fragile and brittle at room temperature, has been reported in 2001
by the materials scientists at the Max-Planck-Institute for Metals Research in Stuttgart. The
significant plastic deformation of this kind of single crystal, obtained at flow stress as low
as 120 MPa (comparable to aluminium or copper alloys) and reaching strains up to 7% at
room temperature and about 3% around 100K will change some of the concepts with which
ceramics are treated as engineering materials today. By jointly working with the German
researchers, we had a priority contribution in 2004 in the TEM study by WBDF technique
of the dislocation cores transformation involved in SrTiO3 plasticity. We have revealed for
the first time the dissociation in partials of the dislocations in SrTiO3 plastically deformed
at 115K and therefore supplying the first direct images in support of a theoretical model
aiming at describing the yet unknown mechanisms of plasticity in this material. An indirect
TEM imaging indication of the same dissociation mechanism has been got in the study of
samples deformed at 78K.
5. New model for anisotropic line broadening caused by crystallite size and size
distribution in the whole pattern fitting
A new model to describe the anisotropic broadening of the diffraction lines caused by
crystallites of not-spherical shape having a lognormal distribution of size has been
proposed. Crystallites of ellipsoidal shape are considered, that allows extending rigorously
for anisotropy the approach of size effect for spherical crystallites and lognormal
distribution reported previously by Popa & Balzar (J. Appl. Cryst. (2002), 35, 338-346.
This approach has been used in the “Size – Strain Round Robin” initiated by the
“International Union of Crystallography” (D. Balzar et al., J. Appl. Cryst. (2004), 37, 911924) – see list of publications). The new model of anisotropic line broadening is
compatible with the whole pattern fitting methods (including Rietveld). To check the
model, a Pawley whole pattern fitting and a measured X-ray diffraction pattern on zinc
oxide were used. The values of the volume averaged column length as function on
direction were compared with those obtained by using the spherical harmonics approach
(Popa, J. Appl. Cryst. (1998), 31, 176-180) accepted as reference in the international
practice. Differences smaller than 5% have been found. In comparison with the spherical
harmonics approach, the advantage of the new model is given by the smaller number of
parameters used in refinement ( J. Appl. Cryst. 37, 911-924, 2004)
INTERNATIONAL COOPERATION:
- Project title: “Synthesis and characterization of nanostructured materials with advanced
functionalities” (2004- 2008) , Partner: Rostock University, Germany
- Project title "Microstructure development of alumina and zirconia nano-composites with
better performances for technological applications in intermediate temperature SOFC’s",
Bilateral cooperation Spain -Romania
88
- Project title: "Physics and chemistry structural aspects of grain boundaries in doped αAl2O3 and ZrO2", Bilateral cooperation Turkey- Romania
PAPERS PUBLISHED OR ACCEPTED FOR PUBLICATIONS IN 2004
1. N.Popescu-Pogrion, R.Bercia, M.Tirnovan ,"Packing models of Y doped α - Al2O3 :
Study of porosity", J. Optoel. Adv. Mat. 6, no. 3, 1071 – 1075, (2004.)
2. N.Popescu-Pogrion, J.Johnson, D.Wouters, G.Norga, O.Van der Biest, "Structural
investigations of ferroelectric Pb(Zr,Ti)O3 thin films prepared by sol-gel method on IrO2
electrodes” J. Optoel. Adv. Mat., 6, no. 3, 1055 – 1058, (2004)
3. G.J.Norga, L.Fe, F.Vasiliu, J.Fompeyrine, J.P.Locquet, O. Van der Biest, “Orientation
selection in functional oxide thin films”, Journal of the European Ceramic Society (Special
issue: Electroceramics VIII - Edited by E. Traversa) 24, 969-974 , (2004)
4. D.Balzar, N.C.Popa, “Elastic-strain tensor and inhomogenous strain in thin films by Xray diffraction”, Thin Solid Films,450, 29-33, (2004)
5. N.C.Popa, B.T.M.Willis, “U4O9: atoms in general sites giving hkl extinctions of special
sites” Acta Cryst. A60, 318-321, (2004)
6. D.Balzar, N.Audebrand, M.R.Daymond, A.Fitch, A.Hewat, J.I.Langford, A.Le Bail,
D.Louer, O.Masson, C.N.McCowan, N.C.Popa, P.W.Stephens, B.H.Toby, “Size-strain
line-broadening analysis of the ceria round-robin sample”, J. Appl. Cryst. 37, 911-924,
(2004)
7. F.Turquier, V.Cojocaru, M.Stir, R.Nicula, C.Lathe, E.Burkel, “Formation and stability
of single-phase Al-Cu-Fe quasicrystals under pressure”, presented at E-MRS Fall Meeting
2004 (Warsaw, Poland, Sept. 2004) – Rev. Adv. Mater. Sci., in press, (2004)
8. V.Kuncser, R.Nicula, U.Ponkratz, A.Jianu, M.Stir, E.Burkel, G.Filoti "Structural phase
transition induced in Fe50Rh50 alloys by high pressure", (Accepted, J. Alloys and
Compounds 2004)
9. V Fruth, M.Popa, A.Ianculescu, M.Stir, S.Preda, G.Aldica "High-Tc phase obtained in
the Pb/Sb doped Bi-Sr-Ca-Cu-O system" J. Eur. Ceram. Soc 24, 1827-1830, (2004)
10. R.Nicula, M.Stir, E.Burkel, “Synchrotron radiation investigation of thermal stability
and grain-growth in pure and metal-doped nanocrystalline TiO2”, Mater. Sci. Forum 467470, 1307-1312, (2004)
11.G.Alexe, T.Passow, Th.Schmidt, J.Falta, H.Heinke, D.Hommel, "Direct investigations
of very thin CdSe layers on ZnSe by out-of-plane grazing incidence x-ray diffraction",
Phys. Stat. Sol (c) 1 no.4 , 702-705, (2004)
12. S.Schumacher, G.Czycholl, F.Jahnke, I.Kudyk, H.I.Rückmann, J.Gutowski, A.Gust,
G.Alexe, D.Hommel, "Polariton propagation in shallow-confinement heterostructures:
89
Microscopic theory and experiment showing the breakdown of the dead-layer concept",
Phys. Rev. B 70: 235340-235347, (2004)
13. G.Roebben, C.Sarbu, T.Lube, O.Van der Biest, “Quantitative determination of the
volume fraction of intergranular amorphous phase in sintered silicon nitride”, Mat. Sci.
Eng. A, 370, 1-2, 453 – 458, (2004)
14 G.Roebben, D.Scitti, C.Sarbu, T,Lauwagie, A.Bellosi, O.Van der Biest, “High
temperature stiffness and damping measurements to monitor the glassy intergranular
phase in liquid-phase sintered silicon carbides”, J. Am. Ceram. Soc. in press.
15. T.G.Berger, A.Leineweber, E.J.Mittemeijer, C.Sarbu, V.Duppel, P.Fischer, “On
formation and crystal structure of the Pd6B phase”, (accepted,Zeitschrift fur
Kristallographie 2004)
BOOKS:
D.Balzar, N.C.Popa “Crystallite Size and Residual Strain/Stress Modeling in Rietveld
Refinement”, Chapter 5, pages 125-145 in the book Diffraction Analysis of the
Microstructure of Materials, Editors E. J. Mittemeijer & P. Scardi, Springer Series in
Materials Science, Springer Verlag, 2004
CONFERENCES:
1. F.Vasiliu, “Cercetarea romaneasca de nanostiinte si materiale nanostructurate in
contextul ERA “, Primul Simpozion National Inginerie si Nanostiinte, Bucuresti, 23 apr.
2004 (Oral presentation)
2. F.Vasiliu, G.J.Norga, L.Fe, D.Wouters, O.Van der Biest, “The role of TiO in the
perovskite nucleation and (111) orientation selection in sol-gel PZT layers”, Conferinta
ROCAM, Constanta, Sept. 2004 (Oral presentation)
3. F.Vasiliu,“Cercetarea de materiale nanostructurate si multifunctionale in INCDFM”,
Al IV-lea Simpozion MATNANTECH, Sinaia, oct. 2004
4. N.Popescu-Pogrion “Structural investigations of nanoresistors; mathematical models
of skin effect” Primul Simpozion National Inginerie si nanostiinte, Bucuresti, 23 aprilie
2004 ( Oral presentation)
5. V.D.Cojocaru, R.Nicula, F.Turquier, M.Stir, M.Knapp, C.Baehtz, E.Burkel, “Pressure
assisted sintering and the BCC-to-FCC phase transition of nanostructured HITPERM
alloys”, Proceedings ROMAT 2004 - “Advanced Materials and Technologies”, 192-198,
2004
6. M.Tirnovan, R.Bercia, S.Constantinescu, N.Popescu-Pogrion, “Study by mathematical
packing models of Y doped α-Al2O3“Proceeding (CD-ROM) of : ICV-16 16th International
Vacuum Conference ; ICSS-12 International Conference on Solid Surface; Nano-8 “8th
90
International Conference on Nanometer-Scale science and Technology ; AIV-17 17th
Vacuum National Symposium, Book 2, ICV-16, ICSS-12, NANO-8, AIV-17, AS+SS 933
[461], Venice, June 28 – July 3 , 2004, (Poster presentation)
7. R.Bercia, M.Tirnovan, N.Popescu-Pogrion, S.Constantinescu, M.A.Gulgun, M.Ruhle,
R.Cannon, “A correlation between the porosity and the grain growth in low Y doped
alpha-alumina. Mathematical model for low porosity.” Proceeding (CD-ROM) of : ICV16 16th International Vacuum Conference ; ICSS-12 International Conference on Solid
Surface; Nano-8 “8th International Conference on Nanometer-Scale science and
Technology ; AIV-17 17th Vacuum National Symposium, Book 2, ICV-16, ICSS-12,
NANO-8, AIV-17, AS+SS 934[527], Venice, June 28 – July 3, 2004, (Poster presentation)
8. N.Popescu-Pogrion, C.Bercia “Nanoresistors with controlled skin effect; mathematical
model “Proceeding (CD-ROM) of : ICV-16 16th International Vacuum Conference ; ICSS12 International Conference on Solid Surface; Nano-8 “8th International Conference on
Nanometer-Scale science and Technology ; AIV-17 17th Vacuum National Symposium,
Venice, June 28 – July 3 , 2004, (Oral presentation)
9. D.Pantelica, F.Vasiliu, P.Ionescu, F.Negoita, “RBS, ERDA, TEM AND SAED
characterization of sol-gel PZT films“, 8th European Conference on Accelerators in
Applied Research and Technology (ECAART-8), September 20-24, 2004, Paris, France,
(Poster presentation) (Nucl. Instr. Meth. B, 2005 , in press)
10. I.Mateescu, B.Capelle, J.Detaint, G.Johnson, L.Dumitrache, C.Bran, "Investigation
by X-ray topography of quartz and langasite resonators", Proc. 4th European Workshop on
Piezoelectric Materials, Iulie 2004, Montpellier, Franta.
11. I.Mateescu, B.Capelle, J.Detaint, G.Johnson, L.Dumitrache, C.Bran, "Vibration
modes analysis by X-ray topography in quartz and langasite resonators", Proc. of IEEE
Int. UFFC 50 th Anniversary Joint Conference, August 2004, Montreal, Canada.
12. R.Nicula, M.Stir, E.Burkel, “Synthesis of nanocrystalline zirconium titanate ceramics
from amorphous precursors and in-situ synchrotron radiation experiments”, 7th Intl. Conf.
on Nanostructured Materials NANO2004 Wiesbaden, Germany, 20-24 June 2004
13. E.Burkel, A.Köhler, M.Stir, R.Nicula, “Advanced new materials for hydrogen storage
and delivery systems”, 11th Symp. "Nutzung regenerativer Energiequellen und
Wasserstofftechnik", FH Stralsund 4-6 Nov. 2004
PhD THESIS:
1. M.STIR "Structure and dynamics of amorphous and nanostructured materials", PhD.
Thesis – Dissertation: July 2004 – University of Rostock, Germany.
91
Laboratory of Microstructure of Defects in Solid Materials
HEAD: Dr. SERGIU V. NISTOR
Tel: (+4021) 493 01 95
Fax: (+4021) 493 02 67
TOTAL EMPLOYEES: 13
RESEARCH TEAM: 11
1. Dr. Sergiu V. NISTOR
2. Dr. Valentin S. TEODORESCU
3. Dr. Leona C. NISTOR
4. Dr. Nicoleta M. GRECU
5. Dr. Corneliu GHICA
6. Dr. Mariana STEFAN
7. Dr. Carmencita D. MATEESCU
8. Phys. Daniela GHICA
9. Dr. Silviu C. SANDU
10. Phys. Adeluta TARPAN
11. Phys. Adrian MARALOIU
12. Dan ZERNESCU
13. Ion ANTON
senior researcher I
senior researcher I
senior researcher I
senior researcher I
researcher
technical assistant
technical assistant
MAIN RESEARCH FIELD
Investigation at atomic scale, by microstructural and spectroscopic methods, of native and
specially/artificially produced defects in bulk and nanostructured solid materials.
Investigations of materials properties changes induced by defects in ordered and partially
disordered solids.
PRINCIPAL RESEARCH DIRECTIONS
1. Atomic structure and quantum properties of native and irradiation induced
defects in insulating and wide-gap semiconducting crystalline materials. Project leader:
Dr. Sergiu V. NISTOR
2. Structural incommensurate, ferroelectric and magnetic phase transitions in
compounds with competitive interactions and colossal magnetoresistance, using
paramagnetic local (atomic) probes. Project leader: Dr. Maria-Nicoleta GRECU
3. Microstructure of oxide nanopowders, thin films and laser processed materials.
Project leader: Dr. Valentin S. TEODORESCU
4. Microstructure transformations and defect associated phenomena in advanced
materials. Project leader: Dr. Leona C. NISTOR
5. New polymeric structures designed for metalic ions removal from industrial
waste waters.Project leader: Dr. Carmencita MATEESCU
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MATERIALS UNDER INVESTIGATION
- Insulating, photosensitive, photorefractive and scintilating crystalline materials.
- Laser deposited complex metal-ceramic thin films and nanostructures.
- Ferro-ferrielectric and ferroelastic crystalline materials.
- Advanced materials for microelectronics and optoelectronics (high-k materials, ZnO,
PMN-PT, hydrogenated Si).
- Wide band-gap semiconductors (crystalline diamond films and boron nitride).
- Incommensurate systems intermediate between translationally periodic ideal crystals and
amorphous systems.
- Sol-gel oxides thin films (ITO, ATO, SiO2, HfO2).
- Molecular magnetic materials.
- Nanodimensional magnetic materials (nanowires, multilayers, granular magnetic
materials, diluted magnetic semiconductors, patterned magnetic films) and
nanocomposites.
-Biomaterials and polymers.
FOREIGN RESEARCH LABORATORIES INVOLVED IN DIRECT SCIENTIFIC
COOPERATION
1. Laboratory EMAT, Department of Physics, University of Antwerp, Antwerp, Belgium.
Head: Prof. G. Van Tendeloo.
2. Laboratory of Spectroscopy and Laser Physics, Dept. of Physics, University of Antwerp,
Antwerp, Belgium. Head: Prof. Dr. E. Goovaerts
3. Laboratory of Magnetic Resonance, Dept. of Physics, Univ. of Gent (RUG), Gent,
Belgium. Head: Prof. Dr. F. Callens
4. Solid State Dept., Institute “Jozef Stefan”, Ljubljana, Slovenia.
Head: Prof. R. Blinc,
5. Laboratory of Experimental Physics II, University of Bayreuth, Bayreuth, Germany.
Head Prof. Dr. M. Schwoerer
7. University “Claude Bernard”, Laboratoire de Physique de la Matiere Condensee et
Nanostructures ( LPMCN), Lyon, France. Project leader: Dr. M. G. Blanchin
8. Universita degli Studi di Torino, Dipartimento di Fisica Sperimentale, Torino, Italy.
Project leader: Prof. Dr. C. Manfredotti.
9. Dept. of Physics, Faculty of Materials Engineering, Technical University of
Czestochowa, Poland. Head: Prof. Dr. R. Hrabanski
10. Inter-university Center for Microelectronics (IMEC), Leuven, Belgium.
Project leader: Dr. H. Bender
11. Department of Physics of Optical Crystals, Institute of Physics of the Academy of
Sciences of the Czech Academy, Prague, Czech Republic. Head: Dr. J. Rosa
12. Departmant of Physics, University of Thessaloniki, Greece.
Project leader: Prof. Dr. N. Frangis
INTERNATIONAL COOPERATIVE SCIENTIFIC PROJECTS:
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- “Microstructural and phase transformations in advanced materials” (2002-2004).
Foreign partners: University of Antwerp and Inter-university Center for Microelectronics
(IMEC), Leuven, Belgium. Romanian project co-promoter: Dr. L. C. Nistor. Project
financed in the frame of 6th science-technology co-operation agreement Romania-Flemish
Community, Belgium.
- “EPR Investigations on relaxors and strong disorded systems” (2003-2005). Foreign
partners: Jozef Stefan Insitute, Ljubliana, Slovenia. Romanian project co-promoter: Prof.
Dr. V. V. Grecu (Physics Faculty) and Dr. M. N. Grecu (INCDFM partner). Project
financed in the frame of science co-operation agreement Romania - Slovenia.
- “Materials and thin films for optoelectronic applications” (2003-2004) Foreign
partner: University “Claude Bernard”, LPMCN., Lyon, France, Romanian project codirector: Dr. V. S. Teodorescu. Bilateral research project.
- “Magnetic resonance in polynuclear metalo-organic systems with Jahn-Teller
transitions and electroluminescent properties” (2003-2005). Foreign partner: University
of Bayreuth, Bayreuth, Germany, Romanian project co-promoter: Dr. M. N. Grecu.
Bilateral research project.
SCIENTIFIC RESULTS. SUMMARY
1. Scientific publications: published 23
accepted or in press 16
2. Communications at International Scientific Meetings: 32
3. Communications at National Scientific Meetings: 7
4. Development grants and contracts: 17
5. Research visits abroad: 5
6. Visitors from abroad: 1
MAIN RESULTS
1. Microstructure and quantum properties of intrinsic and irradiation point defects in wide
band-gap crystalline materials
- Observation and atomic characterization of new point defects in amber colored
and Be-doped c-BN superabrasives and single crystals, by multifrequency ESR
spectroscopy (Phys. Stat. Sol. (a) 201, 2583-2590 (2004); ibid. (a) 201, 2591-2598 (2004)
- Observation and characterization by multifrequency ESR and ENDOR of new
Fe+-type trapped electron centers nanostructure in chlorinated SrCl2 crystals (Phys. Rev. B
70, 024105-7 (2004))
2. Structural incommensurate, ferroelectric and magnetic phase transitions in compounds
with competitive interactions and colossal magnetoresistance, using paramagnetic local
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(atomic) probes
- EPR evidence of grain size effects on the spin dynamics in the paramagnetic
regime of nanosized La2/3Ca1/3MnO3-δ manganites. Correlations between the paramagnetic
behaviour and the existence of two activation energies within the core-shell model. (Appl.
Mag. Res. 27, 139-150 (2004))
- Magnetic resonance characterization of conducting polymer nanocomposites
based on polypyrrole (PPY) and Fe2O3 magnetic particles. (Mol. Crys. Liq. Cryst. 417,
235-243 (2004))
3. Microstructure of oxide nanopowders, thin films and laser processed materials
- Observation of the structure of the mixed Fe2O3-SnO2 nanopowders (J. Phys.
Chem. of Solids 65, 1021-1029 (2004))
- Evidence of the Si nanocrystallites formation by annealing of SiOx thin films.
(Proc. CAS 2004 , Vol.1. pp 59-62 (2004))
4. Microstructure transformations and defect associated phenomena in advanced
materials
- The first determination by TEM and HRTEM techniques of the structure of
crystalline thin films of hydroxipatatite biomaterial prepared by laser ablation. (Mater. Res.
Bull. 39, 2089-2101 (2004)
- Determination of properties of thin films of zirconium silicate prepared by laser
ablation for high-k gate dielectric material. (Mat. Sci. in Semicond. Processing 7, 209-214
(2004)
5. New polymeric structures designed for metalic ions removal from industrial waste
waters
- New metal-chelating polymers for cation complexing. Synthesis and
characterization. (Proc. 40th IUPAC Inter. Symp. on Macromulecules World Polymer
Congress, MACRO-2004, Paris, 4-9 July, 2004)
LIST OF PUBLICATIONS
1. D.Ghica, S.V.Nistor, H.Vrielinck, F.Callens, D.Schoemaker, “X and Q-band ENDOR
study on the Fe+(II) center in chlorinated SrCl2:Fe crystals” Phys. Rev. B 70, 024105-7
(2004)
2. M.Stefan, S.V.Nistor, E.Goovaerts, D.Schoemaker, “EPR probing of the low
temperature structural phases in Rb2ZnCl4 crystals with the Tl0 and Tl2+ centers”, Phys.
Rev. B69, 104107 (2004)
3. L.C.Nistor, G.Van Tendeloo, G.Dinca, “HRTEM studies of dislocations in cubic BN”
Phys. Stat. Sol. (a) 201, 2578-2582 (2004)
4. S.V.Nistor, M.Stefan, D.Ghica, A.Bouwen, E.Goovaerts, “ESR characterization of
point defects in cBN super abrasive crystalline powders” Phys. Stat. Sol. (a) 201, 2583Pag
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2590 (2004)
5. E.Goovaerts, S.V.Nistor, D.Ghica, T.Taniguchi, “High frequency ESR of native point
defects in beryllium doped c-BN single crystals” ,Phys. Stat. Sol. (a) 201, 2591-2598
(2004)
6. L.Nistor, C.Ghica, V.Teodorescu, S.V.Nistor, M.Dinescu, D.Matei, N.Frangis,
N.Vouroutzis, C.Liutas, “Deposition of hydroxiapatite thin films by Nd-YAG laser ablation: a microstructural study”, Mater. Res. Bull. 39, 2089-2101 (2004)
7. M.Sorescu, L.Diamandescu, D.Tarabasanu-Mihaila, V.S.Teodorescu “Nanocrystalline
rhombohedral In2O3 synthesized by hydrothermal and post-annealing pathways”, J. of
Mater. Sci. 39, 675-677 (2004)
8. M.Sorescu, L.Diamandescu, D.Tarabasan-Mihaila, V.S.Teodorescu, B.H.Howard, “Hydrothermal synthesis and structural characterization of (1-x)-Fe2O3-xSnO2 nanoparticles”, J. Phys. Chem. of Solids 65, 1021-1029 (2004)
9. R.Cristescu, I.Stamatin, D.E.Mihaiescu, C.Ghica, M.Albulescu, I.N.Mihailescu,
D.B.Chrisey, “Pulsed laser deposition of biocompatible polymers: a comparative study in
case of pullulan”, Thin Solid Films 453-454, 262-268 (2004)
10. T.F.Stoica, M.Gartner, M.Losurdo, V.Teodorescu, M.Blanchin, T.Stoica, M.Zaharescu, “Spectroellipsometric study of the sol-gel nanocrystalline ITO multilayer films”, Thin
Solid Films 455-456, 509-512, (2004)
11. D.Ghica, S.V.Nistor, H.Vrielinck, F.Callens, E.Goovaerts, D.Schoemaker, “EPR
study of the Fe+(IIa) centre in chlorinated SrCl2:Fe crystals” Phys. Stat. Sol. (c) 2, (1) 5760 (2004)
12. S.V.Nistor, M.Stefan, E.Goovaerts, M.Nikl, P.Bohachek “EPR characterization of
Mn2+ impurity ions in PbWO4 single crystals”,Radiation Measurements 38, 655-658 (2004)
13. M.Filipescu, N.Scarisoreanu, D.G.Matei, G.Dinescu, A.Ferrari, M.Balucani, O.Toma,
C.Ghica, L.C.Nistor, M.Dinescu, “Properties of zirconium silicate thin films prepared by
laser ablation”, Mat. Sci. in Semicond. Processing 7, 209-214 (2004)
14. R.Turcu, I.Peter, O.Pana, L.Giurgiu, N.Aldea, B.Barz, M.N.Grecu, A.Coldea, “Structural and magnetic properties of polypyrrole nanocomposites”, Mol. Cryst. & Liq. Cryst.
417, 235-243 (2004)
15. L.M.Giurgiu, M.N.Grecu, Al.Darabont, O.Raita, X.Filip, O.Pana, D.Toloman, “EPR
investigation of nanosized La0.67Ca0.33MnO3 manganites”, Appl. Mag. Res. 27, 139-150
(2004)
16. L.C.Nistor, G. Van Tendeloo, “Structural transformations in BN formed at high
pressure and high temperature”, Proc. 13-th European Micr. Congr., Antwerp, Belgium,
Aug. 22-27, 2004, Vol. II: Materials Science, ed. G. Van Tendeloo, p. 229-230
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17. C.Ghica, L.C.Nistor, O.Richard, H.Bender, A.G.Ulyashin, G. Van Tendeloo,
“Imaging H2 bubbles and related strain field in silicon wafers exposed to RF hydrogen
plasma”, Proc. 13-th European Micr. Congr., Antwerp, Belgium, Aug. 22-27, 2004, Vol.
II: Materials Science, ed. G. Van Tendeloo, p. 395-396
18. C.Ghica, L.C.Nistor, O.Richard, H.Bender, A.G.Ulyashin, G. Van Tendeloo,
“Quantitative description of the strain field around {111} planar defects in hydrogenated
silicon wafers”, Proc. 13-th European Micr. Congr., Antwerp, Belgium, Aug. 22-27, 2004,
Vol. II: Materials Science, ed. G. Van Tendeloo, p. 405-406
19. R.Turcu, I.Craciunescu, O.Pana, A.Bot, B.Barz, M.N.Grecu, D.Bica, L.Vekas, “A
comparative study of composites based on conducting polypyrrols”, Proc. of 11th European
Conf. on Composits Materials, CD-ROM, N006.pdf (10 pages) (2004)
20. R.Olar, M.Badea, A.Fanaru, M.N.Grecu, E.Iorgulescu, D.Marinescu “Complexes avec
des ligands macrocycliques obtenues lors de la condensation de l’ethylene diamine avec la
tyrosine et formaldehyde», Proc. Troisieme Colloque Franco-Roumain de Chimie
Appliquee (COFrRoCA 2004), 22-26 Septembrie, Slanic-Moldova, Romania, Eds. Alma
Mater Bacau et Tehnica-INFO Chisinau, p. 645-648
21. V.S.Teodorescu, M.L.Ciurea, V.Iancu, M.G.Blanchin, “Microstructure of Si/SiO2
nanocomposite films”, Proc. CAS 2004 , Vol.1. p. 59-62 (2004)
22. M.Mocioi, A.M.Albu, C.Mateescu, “New polymeric materials for chromium removal
from residual tannery waters ” (in Romanian), Industria Pielariei, Ed. Inst. Cerc. Pielarie
11, 234 (2004)
23. M.Mocioi, A.M.Albu, C.Mateescu, C.Simonescu, “Studies and researches regarding
Cu(II) removal by chelating on polymeric supports” (in Romanian), Ecologie Industriala ,
(Ed. OID ICM-ICTCM) 4, 85 (2004)
LIST OF PAPERS ACCEPTED FOR PUBLICATION
1. L.C.Nistor, G.Van Tendeloo, G.Dinca, “Crystallography and structural evolutions in
the HP-HT phase transformation of boron nitride”, Phil. Mag. A (accepted – in press)
2. S.V.Nistor, M.Stefan, E.Goovaerts, M.Nikl, P.Bohachek, “Temperature dependence of
the paramagnetic resonance spectra of Mn2+ impurity ions in PbWO4 single crystals”, J.Phys: Condens.Matter (accepted – in press)
3. V.Ghiordanescu, M.Sima, I.Enculescu, M.N.Grecu, L.Mihut, M.Secu, R.Neumann,
“Manganese and copper doped CdS nanowires photoluminescence”, Phys. Status Solidi A
(accepted – in press)
4. O.Pana, L.M.Giurgiu, Al.Darabont, V.Iancu, M.Ciurea, M.N.Grecu, I.Deac, “Coreshell effects in granular perovskite manganites”, J. Phys. Chem. Solids (accepted – in
press)
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5. M. N.Grecu, D.C. Mateescu, V.V.Grecu, “Cu2+ EPR spectroscopy in LiKSO4” , J. Optoelec. Adv. Materials (accepted – in press)
6. M.N.Grecu, M.Koren, R.Blinc,“EPR evidence of a new low temperature incommensurate phase in Rb2ZnCl4”, J. Optoelec. Adv. Materials (accepted – in press)
7. S.V.Nistor, “Radiation effects and defects in cubic boron nitride. A promising
multifunctional material for severe environment conditions”, Proc. M. R. S. 2004 Fall
Meeting, 29 Nov. – 2Dec. 2004, Boston, U. S. A. (accepted – in press)
8. L.C.Nistor, C.Ghica, D.Matei, G.Dinescu, M.Dinescu, G. Van Tendeloo, “Growth and
characterization of a-axis textured ZnO thin films”,J. Cryst. Growth (accepted – in press)
9. N.Scarisoreanu, D.G.Matei, G.Dinescu, G.Epurescu, C.Ghica, L.C.Nistor, M.Dinescu,
“Properties of ZnO thin films prepared by radiofrequency beam assisted laser ablation”,
Appl. Surf. Sci. (accepted – in press)
10. S.V.Nistor, D.Ghica, A.Bouwen, E.Goovaerts, T.Taniguchi, “Photosensitive and irradiation induced point defects in c-BN crystals”, Phys. Stat. Sol. (a) (to be published)
11. B.Willems, G. Van Tendeloo, L.C.Nistor, C.Ghica, “Strain mapping around
dislocations in diamond structures” Phys. Stat. Sol. (a) (to be published)
12. L.C.Nistor, O.Richard, C.Zhao, H.Bender, G. Van Tendeloo, “The thermal stability of
ALD Zr:Al mixed oxide thin films: an in situ study”,J. Materials Res. (to be published)
13. M.N.Grecu, G.Burducea, V.V.Grecu, I.Zgura, R.Moldovan, T. Beica, “Temperature
variation of surfactant hydrocarbon chain ordering”, Revista de Chimie (accepted - in
press)
14. M.A.Tarpan, V.V.Grecu, M.N.Grecu, I.Zgura, G.Burducea, R.Moldovan, “Electron
paramagnetic resonance investigation of lyotropic crystal liquids” Rom. Rep. Phys. (to be
published)
15. M.Mocioi, A.M.Albu, C.Mateescu, E.Rusen, B.Marculescu, L.Mutihac, “Removal of
Cu(II) from aqeous streams using new metal chelating polymers”, Polymer Intern. (to be
published)
16. M.Mocioi, A.M.Albu, C.Mateescu, A.Iosif, “Chelating processes for chromium removal and recovery from waste waters”, Polymer Intern. (to be published)
PARTICIPATIONS AT INTERNATIONAL SCIENTIFIC MEETINGS.
LIST OF PAPERS/COMMUNICATIONS PRESENTED
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1. L.C.Nistor, G. Van Tendeloo, G.Dinca, “HRTEM studies of dislocations in cubic
BN”,International Workshop on Defects and Impurities in Crystalline Boron Nitride
Compounds, Febr. 20-21, 2004, Diepenbeek-Hasselt, Belgium (oral presentation).
2. S.V.Nistor, D.Ghica, M.Stefan, A.Bowen, E.Goovaerts, “ESR characterization of
point defects in amber colored c-BN super abrasive powders”,International Workshop on
Defects and Impurities in Crystalline Boron Nitride Compounds, Febr. 20-21, 2004,
Diepenbeek-Hasselt, Belgium (oral presentation).
3. E.Goovaerts, S.V.Nistor, D.Ghica, T.Taniguchi, “High Frequency ESR of native point
defects in beryllium doped c-BN single crystals”,International Workshop on Defects and
Impurities in Crystalline Boron Nitride Compounds, Febr. 20-21, 2004, DiepenbeekHasselt, Belgium (oral presentation)
4. A.Mirea, M.N.Grecu, M.Cölle, M.Schwoerer, “EPR on electroluminscent Alq3: thermal
behaviour”, Fruhjahrstagung Deutsche Physikalische Gesellschaft, March 15 -16, 2004,
Regensburg, Germany (poster)
5. N.Scarisoreanu, D.G.Matei, G.Dinescu, G.Epurescu, C.Ghica, L.C.Nistor, M.Dinescu,
“Properties of ZnO thin films prepared by RF beam assisted laser ablation” E-MRS, May
24-28, 2004, Strasbourg, France (oral presentation)
6. M.Filipescu, N.Scarisoreanu, D.G.Matei, G.Dinescu, A.Ferrari, M.Balucani, O.Toma,
C.Ghica, L.C.Nistor, M.Dinescu, “Properties of zirconium silicate thin films prepared by
laser ablation”, E-MRS, May 24-28, 2004, Strasbourg, France (oral presentation)
7. R.Turcu, I.Craciunescu, O.Pana, A.Bot, B.Barz, M.N.Grecu, D.Bica, L.Vekas, “A
comparative study of composites based on conducting polypyrrols”, 11th European Conf.
on Composite Materials, May 31 – June 3, 2004, Rhodes, Greece, (oral presentation)
8. M.G.Blanchin, V.S.Teodorescu, B.Canut, J.A.Roger, C.S.Sandu, K.Daoudi, C.Ghica,
“Transparent conducting oxide (TCO) thin films elaborated by sol - gel route: structure
and properties”, 7th International Conference on Physics of Advanced Materials, June 10
- 12, 2004, Iasi, Romania (oral presentation)
“Structure of iron-tin mixed oxide nanoparticles”, 7th International Conference on Physics
of Advanced Materials, June 10 - 12, 2004, Iasi, Romania (oral presentation)
10. M.Mocioi, AMAlbu, C.Mateescu, C.Simonescu, E.Rusen, B.Marculescu, “Synthesis
and characterization of a new metal chelating polymer for cation complexation”, 40th
IUPAC International Symposium on Macromolecules World Polymer Congress, MACRO
2004, July 4-9, 2004, Paris, France (poster)
11. V.V.Grecu, M.N.Grecu, M.Brasoveanu, O.G.Duliu, “Electron paramagnetic
resonance investigation of irradiated food”, 5th International Balkan Workshop on
Applied Physics, July 5-7, 2004, Constanta, Romania (invited lecture)
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12. S.Constantinescu, M.N.Grecu, I.Bibicu, S.Georgescu, C.Stoicescu, L.Gheorghe,
O.Toma, A.Stefan, “Langasite investigation by XRD, EPR, Mössbauer and optical
spectroscopy”, 5th International Balkan Workshop on Applied Physics, July 5-7, 2004,
Constanta, Romania (poster)
13. L.M.Giurgiu, M.N.Grecu, “Nanometrology by electron paramagnetic resonance”, 5th
International Balkan Workshop on Applied Physics, July 5-7, 2004, Constanta, Romania
(poster)
14. O.Raita, M.N.Grecu, X.Filip, O.Pana, D.Toloman, Al.Darabont, G Ilonca,
L.M.Giurgiu, “EPR of nanometric La2/3Ca1/3MnO3: Influence of the grain size on the
polaron activation energy”, 5th International Balkan Workshop on Applied Physics, July
5-7, 2004, Constanta, Romania (poster)
15. R.Minea, M.Brasoveanu, M.N.Grecu, M.R.Nemtanu, “Preliminary studies of
irradiated spirulina”, 5th International Balkan Workshop on Applied Physics, July 5-7,
2004, Constanta, Romania (poster)
16. S.V.Nistor, “Optical and magnetic resonance spectroscopy of defects in wide–gap
materials. the case of cubic boron nitride”, International Conference on Defects in
Insulating Materials – ICDIM2004, July 11-16, 2004, Riga, Latvia (keynote lecture)
17. D.Ghica, S.V.Nistor, H.Vrielinck, F.Callens, D.Schoemaker, “ESR observation of Fe+
centers in chlorinated SrCl2:Fe crystals”, International Conference on Defects in
Insulating Materials – ICDIM2004, July 11-16, 2004, Riga, Latvia (oral presentation)
18. O.Pana, L.M.Giurgiu, Al.Darabont, V.Iancu, M.Ciurea, M.N.Grecu, I.Deac, “Coreshell effects in granular perovskite manganites”,
International Conference on
Spectroscopies in Novel Superconductors, July 11-16, 2004, Sitges, Spain (oral
presentation)
19. R.Olar, M.Badea, M.N.Grecu, C.Bala, L.Rotariu, E.Cristurean, D.Marinescu,
“Synthesis, characterization and superoxide dismutase like activity of Cu(II) and Zn(II)
complexes with a macrocyclic ligand containing tyrosine residues”, 4th Int. Conf. of the
Chemical Societies of the South-East European Countries on Chemical Sciences in
Changing Times: Visions, Challenges and Solutions (ICOSECS4), July 18-21, 2004,
Belgrad, Serbia and Montenegro (poster)
20. L.C.Nistor, G. Van Tendeloo, “Structural transformations in BN formed at high
pressure and high temperature”, The 13th European Microscopy Congress , EMC 2004,
August 22-27, 2004, Antwerpen, Belgium (poster)
21. C.Ghica, L.Nistor, O.Richard, H.Bender, A.Ulyashin, G. Van Tendeloo, “Imaging H2
bubbles and the related strain field in silicon wafers exposed to RF hydrogen plasma”,
The 13th European Microscopy Congress , EMC 2004, August 22-27, 2004, Antwerpen,
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Belgium (poster)
22. C.Ghica, L.Nistor, O.Richard, H.Bender, A.Ulyashin, G. Van Tendeloo,
“Quantitative description of the strain field around {111} planar defects in hydrogenated
silicon wafers”, The 13th European Microscopy Congress , EMC 2004, August 22-27,
2004, Antwerpen, Belgium (poster)
23. M.N.Grecu, L.M.Giurgiu, “Nanometrology by EPR: Evaluation of the fine particle
diameter and the degree of orientation”, 1st International Conference Advance
Spectroscopies on Biomedical and Nanostructured Systems, September 19-22, 2004, ClujNapoca, Romania (oral presentation)
24. L.M.Giurgiu, M.N.Grecu, “Electron magnetic resonance applied to nanostructured
manganites and metalic nanoparticles”,
1st International Conference Advance
Spectroscopies on Biomedical and Nanostructured Systems, September 19-22, 2004, ClujNapoca, Romania (oral presentation)
25. O.Raita, M.N.Grecu, X.Filip, O.Pana, D.Toloman, A.Darabont, G.Ilonca,
L.M.Giurgiu, “Effects of grain size on the polaronic conduction as evidenced by EPR in
nanoparticles of La2/3Ca1/3MnO3 manganites”, 1st International Conference Advance
Spectroscopies on Biomedical and Nanostructured Systems, September 19-22, 2004, ClujNapoca, Romania (poster)
26. M.R.Nemtanu, M.Brasoveanu, R.Minea, M.N.Grecu, “Green cofee decontamination
by electron beam irradiation”, 8th European Conference on Accelerators in Applied
Research and Technology (ECAART-8), September 20-24, 2004, Paris, France (poster)
27. M.Brasoveanu, M.Nemteanu, R.Minea, M.N.Grecu, E.Mazilu, N.Radulescu,
“Electron beam irradiation for decontamination of spirulina platensis”, 8th European
Conference on Accelerators in Applied Research and Technology (ECAART-8),
September 20-24, 2004, Paris, France (poster)
28. R.Olar, M.Badea, A.Fanaru, M.N.Grecu, E.Iorgulescu, D.Marinescu, "Complexes avec
des ligands macrocycliques obtenues lors de la condensation de l'ethylene diamine avec la
tyrosine et formaldehyde", Troisieme Colloque Franco-Roumain de Chimie Appliquee
(COFrRoCA), Sept. 22-26, 2004, Slanic-Moldova, Romania (oral presentation)
29. V.S.Teodorescu, M.L.Ciurea, V.Iancu, M.G.Blanchin, “Microstructure of Si/SiO2
nanocomposite films”, Conf. CAS 2004, October 4-6, 2004, Sinaia, Romania (oral
presentation)
30. R.Olar, M.Badea, M.N.Grecu, C.Bala, L.Rotariu, E.Cristurean, D.Marinescu,“Kinetics
studies on new complexes with superoxide dismutase (SOD) like activity”, 2ndInt. Aegean
Physical Chemistry Days, October, 7-10, 2004, Ayvalik-Balikesir, Turkey (oral
presentation)
31. S.V.Nistor, “Radiation effects and defects in cubic boron nitride. A promising
multifunctional material for severe environment conditions”, 2004 Fall Materials Research
Society Meeting, November 29 – December 2, Boston, U.S.A. (invited lecture)
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32. M.G.Blanchin, B.Canut, J.A.Roger, Y.Lambert, V.S.Teodorescu, M.Zaharescu,
"Structure et propriétés de films d'oxydes à haute constante diélectrique élaborés par voie
sol-gel", Seminair Rhone-Alpes "Matériaux sol-gel pour l'optique", 6 December, 2004,
Grenoble, France (oral presentation)
PARTICIPATIONS AT NATIONAL SCIENTIFIC MEETINGS.
LIST OF PAPERS/COMMUNICATIONS PRESENTED
1. M.A.Tarpan, V.V.Grecu, M.N.Grecu, I.Zgura, T.Beica, R.Moldovan, “EPR investigation of lyotropic crystal liquids”, Annual Scientific Conference, Faculty of Physics, University of Bucharest, May 19, 2004, Bucharest, Romania (oral presentation)
2. M.Bercu, M.N.Grecu, V.V.Grecu, “Charge states and hyperfine interaction in Alq3“,
2nd National Conference on Theoretical Physics & Titeica-Markov Symposium, August 2629, 2004, Constanta, Romania (oral presentation)
3. M.N.Grecu, A.Mirea, V.V.Grecu, M.Schwoerer, “Paramagnetic centers in Alq3“, The
National Conference in Physics (CNF2004), 9-11 Septembrie 2004, Pitesti, Romania (oral
presentation)
4. M.N.Grecu, D.C.Mateescu, V.V.Grecu, “Cu2+ EPR spectroscopy in LiKSO4“,The
National Conference in Physics (CNF2004), 9-11 Septembrie 2004, Pitesti, Romania
(poster)
5. M.Stefan, S.V.Nistor, E.Goovaerts, D.Schoemaker, "Centrii paramagnetici Tl2+ si Tl0 –
sonde atomice in cristale cu tranzitii de faza structurale", Conceput in Romania CONRO-04, 5-10 Oct. 2004, Bucuresti, Romania (poster)
6. M.Feder, D.Tarabasanu-Mihaila, I.Bibicu, V.Teodorescu, L.Diamandescu, “Sinteza si
caracterizarea a – LiFeO2 nanocristalin”, Simpozionul “Cercetarea stiintifica o punte
spre integrarea europeana”, 3-4 Noiembrie, 2004, Arad, Romania (oral presentation)
7. M.Mocioi, A.M.Albu, C.Mateescu, C.Simonescu, E.Rusen, B.Marculescu, N.Iosipenco,
“Studies on adsorbative removal of chromium using chelatogenes polymeric structures”,
Sustainable Development International Conference, SDIC 2004, 10-13 Nov. 2004,
Bucuresti, Romania (poster)
RESEARCH VISITS ABROAD
1. Defects in diamond-like materials of the B/C/N system.
University of Antwerp (UIA), Antwerp, Belgium,
S. V. Nistor (2 months); M. Stefan (3 months); D. Ghica (2 months)
Visits in the framework of the project - bilateral collaboration Romania-Flanders(Belgium)
2. Microstructural and phase transformations in advanced materials.
EMAT Laboratory, University of Antwerp (RUCA), Antwerp, Belgium,
L. C. Nistor (5 months); C. Ghica (3 months); S. V. Nistor (3 months)
Visits in the framework of the project - bilateral collaboration Romania-Flanders(Belgium)
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3. Magnetic resonance in complex systems with cooperative Jahn-Teller transitions
and electroluminescent properties
Laboratory of Experimental Physics II, University of Bayreuth, Germany,
M. N. Grecu (1 month)
4. Incommensurate phase investigations in new materials with structural phase
transitions and competitive interactions Technical University of Czestochowa, Poland,
M. N. Grecu (10 days)
5. Microstructure of conductive thin films for opto-electronics
Materials Physics Department –DPM – Lyon 1 University, Lyon, France
V. S. Teodorescu (3 months)
VISITORS FROM ABROAD
Prof. Dr. M. G. Blanchin, Claude Bernard University Lyon 1, Materials Physics
Department, visit in the framework of the project-bilateral collaboration Romania-France.
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HEAD: Dr. MIHAIL FLORIN LAZARESCU E

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