Ph.D. Leona Cristina Nistor

Dr. Leona Cristina Nistor

Senior Researcher I

Telephone :
(+4021) 369.01.70/ int.190
Fax :
(+4021) 369.01.77
Email :
Personal data and education

Date and place of birth: May 24, 1946, Bucharest, Romania

Nationality and citizenship: Romanian

MS in Solid State Physics at the University of Bucharest, Romania, June 1969.

PhD in Solid State Physics at the Central Institute of Physics, Bucharest, Romania, June 1979

Scientific work experience
  • Research positions obtained on competitive basis at the Institute of Atomic Physics, National Institute of Materials Physics of Bucharest: 1969-1975 research assistant, 1975-1979 scientific researcher, 1979-1990-1996 senior scientific researcher (degrees III and II), 1996-present, senior scientific researcher (degree I)

  • Research stages abroad and fellowships obtained on competition basis:
    • Visiting scientist at the University of Sussex, Brighton UK, 1970-1971, 3 months
    • Visiting scientist at the Institute of Solid State Physics and Electron Microscopy, Halle, G.D.R., 1976, 1978, 2 weeks each time
    • Visiting scientist at the General Institute of Physics of the Academy of Science of USSR, Moscow, 1984, 1985, 1986, 2-3 weeks each time
    • Visiting scientist at the Technical University Darmstadt, Department of Materials Research, 1996, 4 months
    • Visiting scientist in the Electron Microscopy Laboratory for Materials Science at the University of Antwerp (RUCA), Antwerp, Belgium, 1988, 1989 1 month each time, and:
      • in 1992-1993, 1 year DPWB (Belgian Science Policy Office) fellowship, title of the project: "Structural and phase modifications of solids exposed to nonconventional treatments",
      • in 1993, 3 months EEC-PECO fellowship, title of the project: "Structural effects produced by implantation of optical materials"
      • in 1994-1995, 1 year DPWB fellowship, title of the project: "Image analysis for high resolution electron microscopy. Adaptive pattern recognition. Application to materials science".
  • Coordinator of international scientific projects
    Project leader from the Romanian part in following international projects:
    • INCO COPERNICUS scientific project no. ERBIC 15CT 970710 of the European Commissions for Science Research and Development (1997-2001), involving seven institutions from four European countries (Belgium, Italy, Romania and Russia), project title: "Preparation and assessment of high quality superhard materials"
    • Scientific project no. BIL 97/93 in the framework of the bilateral scientific and technological agreement between the Ministry of Science and Education of Romania and the Ministry of the Flemish Community of Science, Innovation and Media of Belgium, (1998-2001), project title: "In situ formation and structural characterization of semiconductor device materials by means of transmission electron microscopy"
    • Scientific project in the framework of the bilateral scientific and technological agreement between the governments of Romania and Greece, (2000-2002), project title: Composite biocompatible materials based on hydroxyapatite"
    • Scientific project no. BIL/4293W, in the framework of the bilateral scientific and technological agreement between the Ministry of Science and Education of Romania and the Ministry of the Flemish Community of Science, Innovation and Media of Belgium, (2002-2004), project title: "Microstructural and phase transformations in advanced materials".
Scientific activities
  • Over 200 publications, 85% in journals with referee system.
  • Over 1000 citations in international journals and monographs.
  • 4 patents.
  • Invited speaker at different universities: University of Sussex, UK, University of Antwerp, Belgium, G.S.I.–Darmstadt, Germany, NCEM-Lawrence Berkeley National Laboratory, USA., Argonne National Laboratory USA, University of Nantes, France. As recognition of her contributions to the study of structural phase transitions she has been an invited speaker at the Gordon Research Conference on "Phase Transitions", Henniker, New England, USA, 1996.
Scientific achievements. Principal results
  • The use of electron microscopy and electron diffraction techniques for structural researches in materials science.
         Most of the research activities has been devoted to the use of transmission electron microscopy (conventional TEM and high resolution TEM (HRTEM)), accompanied by energy dispersive X-ray spectroscopy (EDS) or electron energy loss spectroscopy (EELS) for the local structural and chemical investigations of advanced materials down to atomic scale. By understanding the structure of the perfect material and by the characterization of defects it has been possible to correlate the structural properties with the other physical properties such as mechanical, optical, electrical or magnetic. With this respect, new complex oxides (Ba8Ta4Ti3O24, Ba10Ta7.04Ti1.2O39, Ba7Sc6Al2O19, Ba5-ySryR2-xAl2Zr1+xO13-x/2 (R= Gd-Lu, Y, Sc) as potential ionic conductors, super hard materials (diamond and cubic BN), superconductor bulk and thin films, materials with colossal magnetoresistance, metallic colloids, nano-phases and quantum dots in optical materials and semiconductor materials has been investigated.
         HRTEM, selected area electron diffraction and spectroscopy methods have been used to study the thin film substrate interfaces, elucidating the importance of interfacial reactions on the structure, morphology and properties of growing films in systems involving heteroepitaxy (III-nitrides on Al2O3, Co and Ni silicides on silicon, diamond or BN on silicon, hydroxyapatite on Ti or TiN, Fe/GaN/Fe on GaAs, ZnO on MgO, Sr0.5Ba0.5Nb2O6 on SrTiO6 or MgO, etc.).
         The attention has also been focused on the research of advanced materials produced by conducted modification of their physical properties. The investigation of these changes required a very good knowledge of the modified materials and a fundamental understanding of the mechanisms involved in the solid state structural transformations and the generation of mezzo- and nano-structures. These processes of material modification largely involve phenomena such as transformations induced by temperature, pressure, irradiation, or composition and subsequent generation and equilibrium of defects. By varying the temperature during the observations in situ studies in the transmission electron microscope of a large variety of synthetic materials which undergo solid state structural phase transitions: Bi2Ti4O11, Bi4Ti3O12, BaAl2O4, 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 and minerals: hollandite, titanite, feldspar and malayaite has been performed. Combining these observations with HRTEM investigations on the same materials, essential micro-crystallographic descriptions of the structural variants, the modulated structures and the generated nano-phases has been obtained.
         In the last years, the attention has been focused on the investigation at atomic scale of nanostructured materials such as mesoporous materials (alumina, silica, ZnS, carbon) and nanostructured carbon materials (nanotubes, nanowalls), nanostructured diamond, BN, CeO2, silicon, etc.
  • The transformation of irradiation defects in insulating materials:
         The main contributions were in the following research directions:
    1. The spectroscopic and microscopic study of the interaction effects between point and extended defects in irradiated alkali halides.
    2. Transmission electron microscopy studies of ordered defects produced in CaF2 by electron irradiation, which closed several years of scientific dispute regarding the nature of these defects.
    3. Electron diffraction and transmission electron microscopy study of the structural aspects related to heavy ion irradiation effects in solids: formation of new phases. Direct observation and characterization of nanostructures, colloids and latent tracks.
  • The interaction of laser beams with materials
         The main contributions were in the following research directions:
    1. The study of high power laser interaction with transparent materials used for the production of high power laser optical components: laser damage studies at 10.6 m, method and apparatus for measuring very low optical coefficients of ultratransparent materials, with the highest sensitivity ever reported (10-7 cm-1), techniques for growing ultratransparent KCl and NaCl large single crystals and for finishing and protection of laser components for high power laser optics.
    2. Laser induced structural changes of metals and ceramics. Synthesis of new compounds by laser irradiation in chemical active media. Detailed structural analysis provided results on the nature, structure, stoichiometry, homogeneity and defects of the new formed surface compounds and on the interface to the irradiated material.
    3. The use of laser in microelectronics: laser annealing of implanted or plasma irradiated silicon, laser formation of silicides, laser induced phase transitions and crystallization and the use of laser reactive ablation for thin film deposition of complex compounds. In all these cases structural investigations were performed to identify the microstructural modifications of the materials under the action of laser beams.
Honors. Affiliations
  • "Constantin Miculescu" Award of Physiscs of the Romanian Academy (1979).
  • Member of the Romanian Society for Physics 1970-present.
  • Member of the Romanian Society for Electron Microscopy 1976-1985.
  • Member of the Romanian Society of Catalysis 1992-1998, 2006-present.
  • Member of the Belgian Society for Electron Microscopy 1992-1999.
Seleted list of papers
  1. Early oxidation stage of copper during c.w. CO2 laser irradiation
    I. Ursu, L.C. Nistor, V.S. Teodorescu, I.N. Mihailescu, L. Nanu, A.M. Prokhorov, V.I. Konov and N.I. Chapliev
    Appl. Phys. Lett. 44, (2), 188-189 (1984)
  2. Periodic structures on the surface of fused silica under multipulse 10.6m laser irradiation
    I. Ursu, I.N. Mihailescu, L.C. Nistor, V.S. Teodorescu, A.M. Prokhorov, V.I. Konov and V.N. Tokarev
    Appl. Opt. 24, (22), 3736-3739 (1985)
  3. Nitridation of Ti and Zr by multipulse TEA-CO2 irradiation in liquid nitrogen
    I. Ursu, I.N. Mihailescu, L. Nanu, L.C. Nistor, M. Popescu, V.S. Teodorescu, A.M. Prokhorov, V.I. Konov, S.A. Uglov, and V.G. Ralchenko
    J. Phys. D, 19, 1183-1188 (1986)
  4. Colloid size distributions in ion implanted glass
    L.C. Nistor, J. Van Landuyt, J.D. Barton, D.E. Hole, N.D. Skelland and P.D. Townsend
    J. Non-Cryst. Sol. 162, 217-224 (1993)
  5. Deposition of high quality TiN films by excimer laser ablation in reactive gas
    I.N. Mihailescu, N. Chitica, L.C. Nistor, M. Popescu, V.S. Teodorescu I. Ursu, A. Andrei, A. Barbonica, A. Luches, M. Luisa De Giorgi, A Perrone, B. Dubreuille and J. Hermann
    J. Appl. Phys. 74, (9), 5781-5789 (1993)
  6. Direct observation of laser induced crystallisation of (a-C:H)-films
    Leona C. Nistor, J. Van Landuyt, V.G. Ralchenko, T.V. Kononenko, Elena D. Obratzsova and V.E. Strelinsky
    Appl. Phys A, 58, 137-144 (1994)
  7. Defects and phase transition in monoclinic natural hollandite: BaxMn8O16
    L.C. Nistor, G. Van Tendeloo and S. Amelinckx
    J. Sol. State Chem., 109, 152-165 (1994)
  8. "In situ" study of the phase transition in Bi2Ti4O11
    L. Nistor, G. Van Tendeloo, S. Amelinckx, V. Kahlenberg and H. Böhm
    J. Sol. State Chem.119, 281-288 (1995)
  9. Nanocrystalline diamond films: transmission electron microscopy and Raman spectroscopy characterisation
    L.C. Nistor, J. Van Landuyt, V.G. Ralchenko, E.D. Obratzova and A.A. Smolin
    Diamond and Related Mater. 6, 159-168 (1997)
  10. Microstructural studies of nanocrystalline CeO2 produced by gas condensation
    N. Guillou, L.C. Nistor, H. Fuess and H. Hahn
    Nanostructured Materials, 8, 545-557, (1997)
  11. HRTEM investigation of latent tracks in GeS and mica induced by high energy ions
    J. Vetter, R. Scholtz, D, Dobrev and L. Nistor
    Nucl. Inst. Meth. Phys. Res. Section B, 141, (1-4) 747-752 (1998)
  12. High resolution electron microscopy and electron spin resonance studies on cubic boron nitrides crystals made by high pressure/high temperature synthesis
    L. Nistor, S. Nistor, G. Dinca, J. Van Landuyt, D. Schoemaker, V. Copaciu, P. Georgioni, N.Arnici
    Diamond and Related Mater. 8, 738-742 (1999)
  13. Microstructural characterisation of diamond films deposited on c-BN crystals.
    L. Nistor, V. Buschmann, V. Ralchenko, G. Dinca, I. Vlasov, J. Van Landuyt and H. Fuess
    Diamond an Related Materials, 9, 269-273 (2000)
  14. Direct evidence of spontaneous quantum dot formation in a thick InGaN epilayer
    L. Nistor, H. Bender, A. Vantomme, M.F. Wu, J. Van Landuyt, K.P. O'Donnel, R. Martin. K. Jacobs and I. Moerman
    Appl. Phys. Lett. 77, (4), 507-509 (2000)
  15. Growth and characterisation of low-temperature grown GaN with high Fe doping
    H. Akinaga, S. Nemeth, J. De Broek, L. Nistor, H. Bender, G. Borghs, H. Ofuchi and M. Oshima
    Appl. Phys. Lett. 77, (26), 4377-4379 (2000)
  16. The influence of the h-BN morphology and structure on the c-BN growth
    L. Nistor, V. Teodorescu, C. Ghica, J. Van Landuyt, G. Dinca and P. Georgeoni
    Diamond and Related Materials 10, (3-7), 1352-1356 (2001)
  17. In situ TEM study of Ni silicide phases formed on (001) Si active lines: structural relationships for NiSi
    V. Teodorescu, L. Nistor, H. Bender, A. Steegen, A. Lauwers, K. Maex and J. Van Landuyt
    J. Appl. Phys. 90, (1), 167-174 (2001)
  18. Formation of amorphous carbon and graphite in CVD diamond upon annealing: a HREM, EELS, Raman and optical study
    L. Nistor, V. Ralchenko, I. Vlasov, A. Khomich, R. Khmelnitskii, P. Potapov and J. Van Landuyt
    Physica Status Solidi (a) 186, (2), 207-214 (2001)
  19. Engeneering of an insulating buffer and use of AlN interlayers: two optimisations for AlGaN-GaN HEMT-like structures.
    Z. Bougrioua, I. Moerman, L. Nistor, B. Van Daele, E. Monroy, T. Palacios, F. Calle and M. Leroux
    Phys. Stat. Sol. (a) 195, 93-100 (2003)
  20. Growth and characterizarion of a-axis textured ZnO thin films
    L.C. Nistor, C. Ghica, D. Matei, G. Dinescu, M.Dinescu and G. Van Tendeloo
    J. Cryst.Growth 227 (1-4) 26-31 (2005)
  21. Crystallographic aspects related to high pressure – high temperature phase transformation of boron nitride
    L.C. Nistor, G. Van Tendeloo and G. Dinca
    Phil. Mag. (A) 85 (11) 1145-1159 (2005)
  22. Characterization of {111} planar defects induced in silicon by hydrogen plasma treatments
    C. Ghica, L.C. Nistor, H. Bemder, O. Richard, G. Van Tendeloo and A. Ulyashin
    Phil. Mag., 86 5137-5151 (2006)
  23. Carbon nanowalls growth by radiofrquency plasma beam enhaced chemical vapour deposition
    S. Vizireanu, L. Nistor, M. Haupt, V. Katzenmayer, C. Oher, and G. Dinescu
    Plasma Process. Polym., 5, 263-268 (2008)
  24. Irradiation defects in superhard cubic boron nitride single crystals
    S. V. Nistor, D. Ghica, M. Stefan, L. C. Nistor, E. Goovaerts and T. Taniguchi
    Nuclear Instrum. & Meth. Phys. B, 266, 2784-2787 (2008)
  25. Synthesis and characterization of Mn2+ doped ZnS nanocrystals self-assembled in a tight mesoporous structure.
    S. V. Nistor, L.C. Nistor, M. Stefan, C.D. Mateescu, R. Birjega, N. Solovieve, M. Nikl
    Superlattices and Microstructures 46, 306-311 (2009)