Annual Report 2012 - Latvijas Universitātes Cietvielu fizikas institūts

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DEPARTMENT OF CRYSTALS PHYSICS AND OPTOELECTRONIC MATERIALS Head of Department Dr. phys. P. Kulis Research topics LABORATORY OF OPTICAL SPECTROSCOPY Head of Laboratory Dr.habil.phys. M.Springis Synthesis of rare-earth doped fluoride and oxyfluoride nanocomposites; studies of radiation energy transfer and relaxation mechanisms in doped nanocomposites by means of optical spectroscopy methods; optical spectroscopy of defects in nanocomposites including studies of up-conversion luminescence. The impact of defects (including radiation) on spectroscopic properties of several complex fluorides structures (LaF 3 , NaYF 4 , NaLaF 4 ) was studied. Along with the mentioned activities a new research topic related to the luminescence processes in rareearth (RE) doped fluoride and oxyfluoride materials was initiated. The studies are organized in two directions: development of synthesis process of different fluoride nanostructures and studies of spectroscopic properties as well as radiation energy relaxation mechanisms in the materials. Special attention is paid to the studies of upconversion process, i.e. studies of visible or even ultraviolet luminescence excited by several lower-energy photons absorption. SiO 2 based glasses and nanostructured glass ceramics with RE doped (Er 3+ , Yb 3+ , Tm 3+ ) LaF 3 nanocrystals were synthesized. Mechanisms of the up-conversion luminescence in these materials were studied at different temperatures. It was found that in silicate glass ceramics with LaF 3 :Er 3+ the main mechanism responsible for the up-conversion luminescence at room temperature is excited state absorption while at lower temperatures energy transfer up-conversion prevails. A synthesis procedure of Er 3+ /Tm 3+ /Yb 3+ (0.25/1/20 mol%) Er 3+ /Tm 3+ /Yb 3+ (2/1.5/20 mol%) Er 3+ /Tm 3+ /Yb 3+ (1.5/4/20 mol%) Up-conversion luminescence color calculated according to CIE chromaticity diagram in NaLaF 4 :Er 3+ , Tm 3+ , Er 3+ materials excited by laser diode at 980 nm. Black arrows indicate trends of the color when the excitation power density is increased 10 NaLaF 4 :RE 3+ was elaborated and systematic studies of the material were performed. It was concluded, that NaLaF 4 :RE 3+ is a perspective material for efficient up-conversion luminescence solutions due to its particularly low phonon energy. Possible applications involve efficient transformation of the infrared radiation into visible (visualization of infrared radiation, enhancement of Solar cells efficiency) and generation of different light colors (light sources). The staff of the laboratory is taking part in the preparation and supervision of practical works in spectroscopy of solid state physics courses for Master students at the University of Latvia (Dr. hab. phys. M. Springis, M. Sc. J. Grube). Dr.phys. A. Sarakovskis is a
lector at the Faculty of Physics and Mathematics University of Latvia (courses: “Materials in Nature and Technics” and “Spectroscopy of Solid State”). Laboratory equipment Picosecond wavelength-tunable laser (EKSPLA) excited luminescence measurement equipment with streak-camera (HAMAMATSU). The equipment allows measurement of time-resolved luminescence spectra at different temperatures (10 K – 300 K) in a broad time range (50 ps – 10 ms) Spectrometer (ANDOR) equipped with CCD camera (ANDOR) for traditional and up-conversion luminescence spectra measurements at different temperatures (10 K – 300 K), excited by Xe lamp or laser diode (808 nm and 980 nm, power up to 1 W). Scientific Staff Dr.hab.phys. Maris Springis Dr.phys. Anatolijs Sarakovskis PhD Students M.Sc. Jurgis Grube M.Sc. Guna Doke Students M. Voss G. Doke (1 week Germany) J. Grube (1 week Germany) Scientific visits abroad Cooperation Latvia Riga Technical University (Prof. A. Medvid). RTU Institute of Nonorganical Chemistry (Dr. J. Grabis, Dr. D. Jankovica). Main results SYNTHESIS AND LUMINISCENCE STUDIES OF Eu 3+ DOPED NaLaF 4 M.Voss, G.Doke, J.Grube, A.Sarakovskis, M.Springis Great attention has been paid for searching of perspective luminescence materials which could be used in various areas, for example, plasma panels or fluorescent lamps. Rareearth (including europium) doped materials have been found to be perspective candidates for such uses thereby further investigation of their properties is required. In this work LaF 3 and NaF mixtures with different EuF 3 concentrations (0.05, 0.1, 0.5, 1 and 2mol%) were annealed at different temperatures (450, 500, 550, 600, 650 O C) to obtain NaLaF 4 :Eu 3+ . For the obtained samples luminescence and excitation spectra as well as luminescence decay kinetics were measured. Based on the experimental results peculiarities of the sample composition, quality and luminescence properties and their dependence on the annealing temperature are discussed. 11
Page 1 and 2: Institute of Solid State Physics Un
Page 3 and 4: CONTENTS Introduction 4 Department
Page 5 and 6: ORGANIZATIONAL STUCTURE OF THE ISSP
Page 7 and 8: The annual report summarizes the re
Page 9: The main source for international f
Page 13 and 14: the samples having different phase
Page 15 and 16: LABORATORY OF MAGNETIC RESONANCE SP
Page 17 and 18: Scientific publications 1. U. Rogul
Page 19 and 20: Main investigations and results ALU
Page 21 and 22: Lectures on Conferences 28 th LU Sc
Page 23 and 24: Main Results LASER CRYSTALLIZATION
Page 25 and 26: CONTROLLED MANIPULATION AND MECHANI
Page 27 and 28: DEPARTMENT OF FERROELECTRICS Head o
Page 29 and 30: Belorussia 1. Institute of solid st
Page 31 and 32: Density and dielectric properties f
Page 33 and 34: CONCENTRATION AND THERMAL PHASE TRA
Page 35 and 36: Latvia; SSPA ”Scientific-Practica
Page 37 and 38: • Δ T εmax : Mn>Co>Fe>Cu~Ni •
Page 39 and 40: Li x Na 1-x Ta y Nb 1-y O 3 Solid S
Page 41 and 42: 34. А.И. Бурханов, И.Е.
Page 43 and 44: 16. Š. Svirskas, M. Ivanov, Š. Ba
Page 45 and 46: 45. С.Н. Каллаев, А.Р.
Page 47 and 48: LABORATORY OF VISUAL PERCEPTION Hea
Page 49 and 50: in terms of colour coordinate dispe
Page 51 and 52: 4. R.Truksa, S.Fomins, M.Ozolins, "
Page 53 and 54: Scientific visits abroad 1. Dr. hab
Page 55 and 56: experimental data. We focused on th
Page 57 and 58: GB1 with oxygen vacancy revealed th
Page 59 and 60: Fig. 4. The thermodynamic stability
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a supercell model was used, and the
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a) b) l [110] d [110] (001) Fig. 9.
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Drain CNT Source Drain GNR Source 5
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The oxygen incorporation energy for
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such as high thermal stability, ver
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STATISTICAL ANALYSIS AND CELLULAR A
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REGIONS OF AZIMUTHAL INSTABILITY IN
Page 75 and 76:
25. A. Gopejenko, Yu.F. Zhukovskii,
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15. S. Piskunov and E. Spohr, "SrTi
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43. P. Merzlakov, G. Zvejnieks, V.N
Page 81 and 82:
XII. Annual Monitory Meeting of Eur
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91. L. Shirmane, A.I. Popov, V. Pan
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115. A.I. Popov, J. Zimmermann, V.
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Estonia Institute of Physics, Tartu
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5. Grigorjeva L., Jankoviča D., Sm
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LABORATORY OF AMORPHOUS MATERIALS S
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Main results ABSORPTION AND LUMINES
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LUMINESCENCE OF FUSED AND UNFUSED B
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enables sensitive and selective det
Page 99 and 100:
LABORATORY OF OPTICAL RECORDING Hea
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HOLOGRAPHIC LITHOGRAPHY IN AMORPHOU
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5. U.Gertners, J.Teteris, The impac
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24. J.Aleksejeva, J.Teteris, A.Tokm
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Israel Technion, Haifa (Dr.S.Stolya
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3. A. Rusakova, J. Maniks, K. Schwa
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• Investigation of energetic stru
Page 113 and 114:
Scheme 2 Synthesis of indane-1,3-di
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The synthesized compounds ZWK-1, DW
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7. A. Vembris, K. Pudzs, I. Muzikan
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20. A. Vembris, K. Pudzs, I. Muzika
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• Ion transfer problems related t
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13. SIA „EMU PRIM”, 14. JSC „
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Main results Laboratory of Solid St
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Flax and Hemp Fiber Functionalizati
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CHARACTERIZATION OF LiFePO4/C COMPO
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Fig.1. Upper panel: 4 × 4 ×4 supe
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Fig.1. Left panel: Schematic view o
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Titania with anatase structure is i
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RESEARCH OF CATHODE MATERIALS FOR L
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17. T Dizhbite, J Ponomarenko, A An
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6. J. Kleperis, B. Sloka, J. Dimant
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33. P. Lesnicenoks, A. Sivars, L. G
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France 1. Institute Laue-Langevin,
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different neutron orbits (11/2[615]
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LABORATORY OF ELECTRONIC ENGINEERIN
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2. For JSC Augstsprieguma tīkls an
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4. By orders of several organizatio
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Partners: Fonons Ltd, Riga Technica
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Annual Report 2012 - Latvijas Universitātes Cietvielu fizikas institūts

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