Investigations of LiNb1−xTaxO3 nanopowders obtained with mechanochemical method

Nanocrystalline compounds LiNb1−xTaxO3 of various compositions (x = 0, 0.25, 0.5, 0.75, 1) were synthesized by high-energy ball milling of the initial materials (Li2CO3, Nb2O5, Ta2O5) and subsequent high-temperature annealing of the resulting powders. Data on the phase composition of the nanopowders were obtained by X-ray diffraction methods, and the dependence of the structural parameters of LiNb1−xTaxO3 compounds on the value of x was established. As a result of the experiments, the optimal parameters of the milling and annealing runs were determined, which made it possible to obtain single-phase compounds. The Raman scattering spectra of LiNb1−xTaxO3 compounds (x = 0, 0.25, 0.5, 0.75, 1) have been investigated. Preliminary experiments have been carried out to study the temperature dependences of their electrical conductivit

Optical Absorption and Luminescence of Gd3Ga5O12:Cr,MgGd_{3}Ga_{5}O_{12}:Cr,Mg Epitaxial Films

The optical absorption, emission spectra and luminescence decay kinetics under photoexcitation of $Gd_{3}Ga_{5}O_{12}$ (GGG) garnet epitaxial films doped with $Cr^{3+}$ ions and co-doped with $Cr^{3+}$ and $Mg^{2+}$ ions have been investigated. Luminescence of the GGG:Cr films due to $\text{}^{4}T_{2}$ → $\text{}^{4}A_{2}$ and $\text{}^{2}E$ → $\text{}^{4}A_{2}$ transitions in $Cr^{3+}$ ions have been observed. Increase of the activator ions concentration has an influence on the intensity and decay time of $Cr^{3+}$ ions photoluminescence. Introduction of the magnesium ions leads to partial transformation of chromium valence state $(Cr^{3+} \rightarrow Cr^{4+})$ and to the appearance of a broad absorption band with the maximum at 860 nm. The narrow lines with luminescence maxima at 704 and 706 nm have arisen in the highly doped GGG:Cr,Mg films

Electrical properties of n‑HgCdTe MIS structures with HgTe single quantum wells

Hg1−xCdxTe grown by molecular beam epitaxy including HgTe single quantum well (SQW) with thickness of 6.5 nm wer

Optical in situ Study of Reduction/Oxidation Processes in Cr,Mg:YAG Epitaxial Film

The changes of the optical absorption spectra of Cr,Mg:YAG epitaxial film caused by high-temperature redox treatment are investigated by means of in situ spectroscopy. The spectra were registered in the visible and near-IR spectral regions at temperatures up to 1100 K. The kinetics of optical absorption changing were obtained in the temperature range from 936 K to 1091 K and were described by mathematical model connecting the chromium recharging process with oxygen vacancies diffusion. The parameters of the model were determined from the approximations of the experimental kinetics

Interaction of rare earth aluminates in the PrAlO3_{3}-and LaAlO3_{3}-based systems

Series of Pr$_{1-x}$R$_x$AlO$_3$ and La$_{1-x}$R$_x$AlO$_3$ (R – rare earth element) specimens were preparedby a combination of solid-state reaction in air and arc-melting in Ar atmosphere. Crystalstructure, thermal expansion and phase transformation of Pr$_{1-x}$R$_x$AlO$_3$ and La$_{1-x}$R$_x$AlO$_3$ solidsolution have been investigated by means of X-ray powder diffraction technique and thermalanalysis in wide temperature range. The phase diagrams of some PrAlO$_3$−RAlO$_3$ andLaAlO$_3$−RAlO$_3$ pseudo-binary systems have been constructed

Optical Properties of GGG Epitaxial Films Grown from PbO-B₂O₃-V₂O₅ Flux

The paper reports a growth of the high-quality Gd₃Ga₅O₁₂ (GGG) homoepitaxial films by the liquid phase epitaxy technique using the PbO-B₂O₃ and PbO-B₂O₃-V₂O₅ fluxes. The influence of the flux composition containing V₂O₅ as well as the growth temperature is discussed basing on the optical absorption and the electron probe micro analysis results