Browsing Zinātniskie raksti (CFI) / Scientific articles by Issue Date
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Hardening of Steel Perforated Tape by Nd:YAG Laser
(Trans Tech Publications Ltd., 2017)One of the directions of application of the perforated metal material is their use as cutting elements in the production of processing tools. In this case it is necessary to carry out hardening of cutting surfaces to ... -
Luminescence properties of LiGaO2 crystal
(Elsevier B.V., 2017)The comprehensive spectral study of lithium metagallate LiGaO2 crystal has been done including methods of pump-probe techniques, optical absorption, photoluminescence, luminescence kinetics, thermoluminescence and polarised ... -
Electromechanical Properties of Ba(1–x)SrxTiO3 Perovskite Solid Solutions from First-Principles Calculations
(ACS Publications, 2017)An enhancement of the piezoelectric properties of lead-free materials, which allow conversion of mechanical energy into electricity, is a task of great importance and interest. Results of first-principles calculations of ... -
Use of site symmetry in supercell models of defective crystals: Polarons in CeO2
(Royal Society of Chemistry, 2017)In supercell calculations of defective crystals, it is common to place a point defect or vacancy in the atomic position with the highest possible point symmetry. Then, the initial atomic structure is often arbitrary distorted ... -
Effect of Mg2+ ions co-doping on luminescence and defects formation processes in Gd3(Ga,Al)5O12:Ce single crystals
(Elsevier B.V., 2017)Photo- and radioluminescence and thermally stimulated luminescence characteristics of Ce³⁺ - doped and Ce³⁺, Mg²⁺ co-doped Gd3(Ga,Al)5O12 (GAGG) single crystals of similar composition are investigated in the 9–500 K ... -
Thermodynamic stability of stoichiometric BiFeO3 : hybrid DFT study
(Royal Society of Chemistry, 2017)BiFeO3 perovskite attracts great attention due to its multiferroic properties and potential use as a parent material for Bi1-xSrxFeO3-δ and Bi1-xSrxFe1-yCoyO3-δ solid solutions in intermediate temperature cathodes of oxide ... -
First-principles calculations of oxygen interstitials in corundum: A site symmetry approach
(Royal Society of Chemistry, 2017)Using site symmetry analysis, four possible positions of interstitial oxygen atoms in the α-Al2O3 hexagonal structure have been identified and studied. First principles hybrid functional calculations of the relevant atomic ... -
Analysis of self-trapped hole mobility in alkali halides and metal halides
(Elsevier B.V., 2017)The small radius hole polarons (self-trapped holes (STH) known also as the Vk centers) are very common color centers observed in numerous alkali halides and alkaline-earth halides. Their mobility controls the rate of ... -
Novel octahedral tilt system a + b + c + in (1 − x)Na0.5Bi0.5TiO3–xCdTiO3 solid solutions
(Springer Verlag, 2017)(1 − x)Na0.5Bi0.5TiO3–xCdTiO3 solid solutions in the whole concentration range (0.0 ≤ x ≤ 1.0) were studied by means of X-ray diffraction, dielectric spectroscopy and polarization measurements. The study was mainly focused ... -
Direct and indirect determination of electrocaloric effect in Na0.5Bi0.5TiO3
(AIP Publishing, 2017)Direct and indirect studies of the electrocaloric effect were carried out in poled and depoled Na0.5Bi0.5TiO3. For this purpose, polarization and electrocaloric effect temperature change measurements were made at different ... -
Structural, magnetic, dielectric and mechanical properties of (Ba,Sr) MnO3 ceramics
(Elsevier Ltd, 2017)Ceramic samples, produced by conventional sintering method in ambient air, 6H-SrMnO3 (6H-SMO), 15R-BaMnO3 (15R-BMO), 4H-Ba0.5Sr0.5MnO3 (4H-BSMO) were studied. In the XRD measurements for SMO the new anomalies of the lattice ... -
All-organic electro-optic waveguide modulator comprising SU-8 and nonlinear optical polymer
(OSA - The Optical Society, 2017)In this paper we describe the principles of operation as well as the fabrication and testing steps of an all-organic waveguide modulator. The modulator comprises an SU-8 core and an electro-optic host-guest polymer cladding. ... -
Simulation of Young's moduli for hexagonal ZnO [0 0 0 1]-oriented nanowires: first principles and molecular mechanical calculations
(IOP Publishing, 2017)Morphologically reproducible wurtzite-structured zinc oxide nanowires (ZnO NWs) can be synthesized by different methods. Since ZnO NWs have been found to possess piezoelectricity, a comprehensive study of their mechanical ... -
Thin film organic thermoelectric generator based on tetrathiotetracene
(Wiley-VCH Verlag, 2017)Thin films of p- and n- type organic semiconductors for thermo-electrical (TE) applications are produced by doping of tetrathiotetracene (TTT). To obtain p-type material TTT is doped with iodine during vacuum deposition ... -
Orientation of the electric field gradient and ellipticity of the magnetic cycloid in multiferroic BiFeO3
(Taylor and Francis Ltd., 2017)The paper deals with the hyperfine interactions observed on the 57Fe nucleus in multiferroic BiFeO3 by means of the 14.41-keV resonant transition in 57Fe and for transmission geometry applied to the random powder sample. ... -
Multimode time-dependent gyrotron equations for different time scales
(American Institute of Physics Inc., 2017)Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. For a long time, the gyrotron theory was developed assuming that the transit time of electrons through the interaction ... -
Upconversion luminescence of a transparent glass ceramics with hexagonal Na(Gd,Lu)F4 nanocrystals
(Elsevier B.V., 2017)Novel Er3+ doped transparent glass ceramics containing hexagonal Na(Gd,Lu)F4 nanocrystals were prepared from oxyfluoride glasses. The distribution of rare earth ions in the crystalline and glassy phase has been analyzed ... -
Phase transitions and upconversion luminescence in oxyfluoride glass ceramics containing Ba4Gd3F17 nanocrystals
(Elsevier B.V., 2017)Novel transparent Er3+ doped oxyfluoride glass-ceramics containing Ba4Gd3F17 nanocrystals were prepared by melt quenching followed by heat treatment of as-prepared glasses. The phase composition and microstructure were ... -
Electron paramagnetic resonance and photoluminescence investigation of europium local structure in oxyfluoride glass ceramics containing SrF2 nanocrystals
(Elsevier B.V., 2017)Different compositions of europium doped aluminosilicate oxyfluoride glass ceramics prepared in air atmosphere have been studied by electron paramagnetic resonance (EPR) and optical spectroscopy methods. X-ray diffraction ... -
First principles modeling of 3d-metal doped three-layer fluorite-structured TiO2 (4,4) nanotube to be used for photocatalytic hydrogen production
(Elsevier, 2017)We have estimated theoretically the photocatalytic suitability of thinnest single-wall fluorite-structured titania (4,4) nanotube (NT) possessing three layers each (O-Ti-O) and doped by Sc, V, Cr, Mn, Fe, Co, Ni, Cu and ...