«ANNUAL REPORT Riga 2012 Annual Report 2011, Institute of Solid State Physics, University of Latvia. Editor: A.Krumins. Composed matter: A.Muratova. ...»
6. E. Klotins, A.I. Popov, V. Pankratov, L. Shirmane, D. Engers, Numerical evidences of polarization switching in PMN type relaxor ferroelectrics, Integrated Ferroelectrics, 123 (2011) 32-39 Presentations at scientific conferences, congresses, meetings, schools and workshops I. ISSP Conference (Riga, Latvia, February, 2011)
1. V. Pankratov, A.N. Larsen, B.B. Nielsen, ZnO nanocrystals/SiO2 multilayer structures fabricated by RF-magnetron sputtering, Abstracts p. 42.
2. V. Pankratov, V. Osinniy, A.N. Larsen, B.B. Nielsen, Si nanocrystals in SiO2: Optical studies in the vacuum ultraviolet range, Abstracts p. 43.
3. V. Pankratov, A.I. Popov, S.A. Chernov, C. Feldmann, Mechanism for enrgy transfer processes between Ce3+ and Tb3+ in LaPO4:Ce, Tb nanocrystals by time-resolved luminiscence spectroskopy, Abstracts, p. 44.
4. V. Pankratov, L. Shirmane, A.I. Popov, A. Kotlov, C. Feldmann, Luminescence of nano- and macrosized LaPO4:Ce,Tb excited by synchrotron radiation, Abstracts p. 45.
5. V. Osinniy, V. Pankratov, A.N. Larsen, B.B. Nielsen, Vertical charge-carrier transport in Si nanocrystal/SiO2 multilayer structures, Abstracts p. 46.
6. L. Shirmane, V. Pankratov, A.I. Popov, A. Kotlov, C. Feldmann, Luminescnece properties of YVO4:Eu3+ nanocrystals under synchrotron radiation, Abstracts p. 47.
7. L. Shirmane, V. Pankratov, W. Strek, W. Lojkowski, Peculiarities of luminescent properties of cerium doped YAG transparent nanoceramics, Abstracts p.48.
II. International conference "Functional materials and nanotechnologies" FM&NTApril 05-08, 2011, Riga, Latvia)
1. I. Karbovnyk, V. Lesivtsiv, I. Bolesta, S. Velgosh, I. Rovetsky, V. Pankratov, A.I.
Popov Optical Properties of BiI3 Nanoclusters Embedded in CdI2 Layered Crystals, Abstracts), Book of Astracts p. 116.
2. A.I. Popov, V. Pankratov, D. Jakimovica, E. Klotins, L. Shirmane, A. Kotlov, Luminescence Properties of BaZrO3 under Synchrotron Radiation, Book of Abstracts, p. 117.
3. A.I. Popov, V. Pankratov, V. Bratus, A. Kotlov, Electronic Excitation and Luminescence of 3C-SiC Pure and Neutron Irradiated Silicon Carbide, Book of
Abstracts, p. 118.
4. A.I. Popov, V. Pankratov, A. Lushchik, E. Klotins, L. Shirmane, V.E. Serga, L.D.
Kulikova, A. Kotlov, VUV Luminescence of MgO, Book of Abstracts p. 119.
5. P.V. Savchyn, V.V. Vistovskyy, A.S. Voloshinovskii, V. Pankratov, A.I. Popov, A.
Kotlov, Luminescence of Eu2+-doped LaCl3 microcrystals incorporated in the NaCl host, Book of Abstracts p. 122.
III. E-MRS Spring Meeting (Nice, France) (May 2011)
1. V. Pankratov, A.I. Popov, E.A. Kotomin, Polarons in Complex Oxides, E-MRS Spring Meeting, Abstracts: L2-15.
2. A.I. Popov, E.A. Kotomin, V. Pankratov and J. Maier, Generalization of Rabin-Klick diagram for a whole family of alkali halides, E-MRS Spring Meeting, Abstracts: L2IV. NATO Advanced Research Workshop: Nanodevices and Nanomaterials for Ecological Security, Jūrmala, Latvia, (June 2011)
1. V. Pankratov, A.I. Popov, L. Shirmane, A. Kotlov, C. Feldmann, Luminescence properties of nanosized phosphors under synchrotron radiation.
2. A.I. Popov, V. Pankratov, L. Shirmane, A. Kotlov, Synchrotron radiation studies on luminescence properties of macro- and nanosized MgAl2O4.
V. International Workshop of Advanced Optical Materials (IWASOM) 2011, Gdansk, Poland, (July 2011)
1. V. Pankratov, L. Shirmane, A.I. Popov, A. Kotlov, C. Feldmann, Luminescence properties of YVO4:Eu3+ nanocrystals under synchrotron radiation, Book of Abstracts p. 63.
2. V. Pankratov, L. Shirmane, A.I. Popov, A. Kotlov, P. Glohowski, W. Strek, Luminescence of MgAl2O4:Cr3+ nanocrystals under synchrotron radiation, Book of Abstracts p. 84.
Fig.1: PL spectra for Si NCs with different diameters under 150 nm (8.27 eV) excitation at 8 K (left). PL excitation spectra for Si NCs with different diameters are depicted in the right graph [V. Pankratov et al., Phys. Rev. B 83 (2011) 045308].
The dependence of the photoluminescence excitation spectra on the nanocrystals size was experimentally established for the first time (Fig.1). It is shown that the photoluminescence excitation and absorption spectra are significantly blueshifted with decreasing Si nanocrystal size. A detailed comparison of photoluminescence excitation and absorption spectra with data from theoretical modeling has been done. It is demonstrated that the experimentally determined blueshift of the photoluminescence excitation and absorption spectra is larger than the theoretical predictions. The influence of point defects in the SiO2 matrix on the optical and luminescence properties of the embedded Si nanocrystals was clearly established and demonstrated. Moreover, it is demonstrated that no energy transfer takes place between the SiO2 and Si nanocrystals when the excitation energy is higher than the band-to-band transition energy in SiO2.
LaPO4:Ce,Tb AND YVO4:Eu NANOPHOSPHORS: LUMINESCENCE STUDIES IN
THE VACUUM ULTRAVIOLET SPECTRAL RANGE
synchrotron radiation, ranging from 3.7-40 eV. Special attention was paid to VUV spectral range, which is not reachable with commonly used lamp and laser sources.
Fig. 2. Comparison of excitation spectra of Tb3+ (a) and Ce3+ (b) emissions for bulk and nanosized LaPO4:Ce,Tb. Excitation spectra of Eu3+ emission in the bulk, nanosized, and nanosized YF3-covered YVO4:Eu at 10 K in 3.5–10 eV (c) spectral range [V. Pankratov et al., J. Appl. Phys. 110 (2011) 053522].
It was demonstrated that nanoparticles’ surface can drastically change emission and excitation spectra of nanopowders, comparing with corresponding bulk materials (Fig 2.).
Especially significant distinctions between excitation spectra for nano and bulk materials were observed under relatively high energy excitation (exceeding 10 eV). It was suggested that surface-related loss processes, namely electron-hole pairs’ non-radiative annihilation at the surface, are responsible for the suppression of energy transfer processes from the host lattice to impurity ions and, subsequently, for rare-earth emission degradation under high energy excitations in nanosized materials.
DEPARTMENT OF SEMICONDUCTOR MATERIALS
AND SOLID STATE IONICSHead of Division Dr.phys. A.Lusis Research areas and expertise Electrophysics and electrochemistry of specific semiconductor materials, mixed conductors, ion conductors (transition metal oxides, bronzes, metal hydrates, solid electrolytes, nanostructured and porous materials, composites etc.) Material preparation methods: thin and thick film technologies, sol-gel process, leaching, sonochemical processes, electron-beam technology Material characterization by spectroscopic methods (Raman scattering, FTIR spectroscopy, optical and X-ray absorption, EXAFS, XANES), electrical and electrochemical impedances, AFM, TGA/DTA, etc
Solid state ionics:
- electro-, photo-, thermo-, chemo- or gaso-chromic phenomena in transition metal oxides
- structural changes due to ion intercalation
- lattice dynamics and structural and electronic phase transitions
- solid state reactions at interfaces electrode – solid electrolyte
- gases and ions sensing phenomena and detection technologies Functional coatings and multi layer electrochemical systems Hydrogen absorption phenomena in metals, semiconductors and insulators Development of hydrogen generation equipment and new nano structured materials for hydrogen storage New measurement technologies and instruments with artificial intellect (encl., eNose) Development methods and techniques for quality and reliability testing for lead –free joints of PCB Hydrogen technologies (production, storage, transportation, application); renewable energy technologies (solar, wind, static electricity, water, microbial fuel cells);
Development of cathode materials for Lithium thin film batteries;
Gas sensors and sensor arrays; odour recognition and removal with adsorbent and low temperature plasma discharge technologies.
Tritium analysis Research Topics Ion transfer in solids, over two phase interfaces and composites as well as structural changes due to ion intercalation, lattice dynamics and structural and electronic phase transitions.
Ion transfer problems related to electro-, photo-, chemo-, thermo-chromic phenomena in transition metal oxides as well as to solid state reactions at interfaces electrode – solid electrolyte.
Application of electrical and electrochemical impedances for characterization of ionic systems, nanostructured and porous materials, composites.
Development of nanostructuring methods for functionalization of plate glass and fiber glass surfaces as well investigation influence of ultrasound on leaching processes, pores structure and ion exchange of glass fibers.
Application of thermal analyses (TGA/DTA) and sorptometry for investigation of porous materials and absorbing capacity of functional species.
Investigation of stability of materials for electrochemical multi layer systems and electrochromic coatings as well as intergrain activity in solid electrolyte layers based on polymer composites.
Development methods and techniques for functilization Development methods and techniques for quality and reliability testing for lead-free joints of printed circuit boards.
Servicing of common research facilities: thin film vacuum coating machines, TGA/DTA equipment and powerful ultrasound bath-reactor.
Membranes and membrane/electrode systems for fuel cells and gas filtration.
Investigations of tritium release properties of neutron multiplier beryllium materials for fusion reactor development. Analysis of tritium distribution in plasma-facing carbonbased components.
The technologies for hydrogen production, storage, transportation, applications in transport and stationary applications; for energy storage and electricity/heat generation;
synthesis and research of new materials for hydrogen technologies (electrodes in electrolysers and microbial fuel cells, structured nanomaterials for photoelectrolysis, hydrogen storage media, polymer membranes and membrane-electrode assemblies for fuel cells);
Lithium intercalation materials and their application for thin film rechargeable battery;
the technologies for electricity generation from renewables (solar, wind, static electricity, water, algae and microorganisms);
Gas sensors and sensor arrays for gas and odour monitoring; odour recognition and removal with adsorbents and ozone technologies; development of technologies.
Investigations of tritium release properties of neutron-irradiated beryllium.
Development of innovation technology for producing of solar silicon using electron-beam technology Mathematical modeling of silicon melting by electron beam
Laboratories of Semiconductor Material Department Laboratory of Solid State Ionics – Head of Laboratory Dr. phys. A.Lusis Laboratory of EXAFS Spectroscopy – Head of Laboratory Dr. hab. phys.J.Purans Laboratory of Hydrogen and Gass Sensors – Head of Laboratory Dr.J.Klepers
7. University of Latvia (LU):
Faculty of Physics and Mathematics.
Faculty of Chemistry (Dr. A.Vīksna) & Faculty of Biology (Prof. I.Muiznieks) Faculty of Medicine Faculty of Economics and Management (Prof. B.Sloka) Institute of Chemical Physics (Dr. G. Kizane)
3. Riga Technical University (RTU):
Institute of Silicate Materials (Prof. G.Mežinskis).
Institute of Inorganic Chemistry (Dr. J. Grabis, Dr. E.Palcevskis, Dr. A. Dindune ) Institute of Idustrial Electronics and Energetic (Prof. L.Ribickis).
Institute of Textile Material Technologies and Design (Prof. I.Baltiņa) Institute of Biomaterials and Biomechanics (Dr. I.Lasenko)
4. Latvia University of Agriculture, Research Institute of Agricultural Machinery,
5. Institute of Physical Energetics, Riga
6. Latvian Electrical Engineering and Electronics Industry Association (LEtERA)
7. Latvian Electroindustry Business Innovation Centre (LEBIC).
8. Latvian Association for Textile and Clothing Industry
9. Latvian Hydrogen Association
10. Housing and Environment Department of Riga City Council, Riga,
11. JSC “Valmiera Glass Fiber”
12. JSC “Sidrabe”
14. JSC „Riga Electric Machine Building Works”,
13. SIA „EMU PRIM”,
14. SIA “Adviser Union”
15. IC „Plazma PL”, France CRMCN/CNRS, Universite de la Mediterranee, UMR 6631 CNRS, Marseille, France Czech Republic University of Ostrava, Faculty of Science (Prof. Bogumil Horák) Germany
1. Max-Planck-Institut für Festkörperforschung (Stuttgart, Germany) – Prof. J.Maier.
2. Kassel University (Prof. Jürgen Zick)
3. Institute of Solid State Research, Forschungszentrum Jülich (Jülich, Germany) –C. Lenser, Dr. R. Dittmann, Prof. K. Szot, Prof. R.Waser.
1. Dipartimento di Fisica, Università di Trento (Trento, Italy).
2 IFN-CNR, Institute for Photonics and Nanotechnologies, Section "ITC-CeFSA" of Trento, Italy.
3 Università della Calabria (Arcavacata di Rende, Italy).
1. University of Vilnius - Department of Physics (Prof. A.Orliukas)
2. Lithuanian Institute of Energetic (Prof. D. Milcius) Norway Institute for Energy Technology, Kjeller Russia
1. Joint Institute for Nuclear Research (Dubna, Russia) - Dr. S.I. Tjutjunnikov.
2. St. Petersburg University (St. Peterhof, Russia) - Prof. R.A. Evarestov
3. Moscow State Engineering Physics Institute (Moscow, Russia) – Prof. A.Menushenkov.
Sweden The Angstrom Laboratory, Uppsala University, Uppsala, Sweden – Prof. C.G.Granqvist.
Ukraine State Scientific Recearch Institute “HELIUM”, Vinnitsa, Ukraine – Dr. V. Panibratskiy
Participation in Research Projects:
1. ESF Project "Nanomaterials for perspective energy effective solutions", No.
2. ESF Project "Nanomaterials for perspective energy effective solutions", No.