I. Yu. Filatova

Lanthanum oxide sulfurization in ammonium rhodanide vapor

We have studied phase formation processes in the La-O-S system during La2O3 sulfurization in ammonium rhodanide vapor and identified the sequence of steps in lanthanum oxide conversion into oxysulfides and lanthanum sulfide using X-ray diffraction, IR absorption spectroscopy, and Raman spectroscopy. In the initial stage of the sulfurization process, we observed the formation of lanthanum dioxydisulfide, which converted into lanthanum dioxymonosulfide and lanthanum sesquisulfide during further sulfurization. Our results demonstrate that low structural perfection of lanthanum oxide allows reactive sulfur to penetrate the surface layer, which probably favors lanthanum dioxydisulfide formation.

XES investigation of the layered vanadium-substituted copper-chromium disulfides

XRD data on the layered vanadium-substituted copper-chromium disulfides (CuCr1−xVxS2, x = 0−0.4) are compared with the data obtained by X-ray emission and photoelectron spectroscopies.

Vapor phase growth of nanostructured yttrium oxysulfide films

Nanostructured yttrium oxysulfide films have been prepared via vapor phase growth. The first step was the deposition of 50-nm-thick nanostructured yttria films from yttrium dipivaloylmethanate vapor at 525°C. Next, the films were sulfided in ammonium thiocyanate vapor at temperatures from 800 to 1100°C. Hexagonal yttrium oxysulfide was obtained at 900°C and higher temperatures. The films consisted of densely packed grains about 50 nm in size.

XANES investigation of manganese sulfide solid solutions

A comprehensive study of the valence state and the local coordination character of Mn1-xYbxS (x = 0; 0.01; 0.05) solid solutions has been performed using X-ray absorption spectroscopy combined with finite difference method calculations. The good agreement between experimental and calculated data indicates that cationic substitution does not lead to significant changes in the manganese local coordination character. The ytterbium atoms are found to be in the trivalent state, while the manganese and sulfur atoms are in the divalent state.

Magnetic resonance in a gallium-doped Cu–Cr–S structure

A layered Cu–Cr–S structure doped with Ga ions and consisting of single-crystal CuCrS2 layers, embedded with thin plates of spinel phases CuCr2S4 and CuGaxCr2–xS4, has been studied using the magnetic resonance and magnetic susceptibility methods. The Curie temperature and the saturation magnetization of the spinel phases of the samples have been determined. The spinel phase layer thickness has been estimated.

Xanes of X-ray absorbtion K edges of chromium dichalcogenides CuCr1-xM′xS2 and MCrX2

In the work X-ray K edges of chromium dichalcogenides CuCr1-xMx′S2 (M = V, Fe; x = 0-0.40) and MCrX2 (M = Cu, Ag, Na; X = O, S, Se) were studied experimentally and theoretically. Comparison of fine structures of experimental XANES spectra obtained using a synchrotron radiation source and theoretical absorption spectra modelled using FDMNES software package allows one to study the influence of types of intercalate M, chalcogene X and also the effect of the cation substitution of chromium atoms by vanadium and iron on XANES structure of K edges in CuCr1-xMx′S2 and MCrX2.

X-ray and Auger microprobe studies of vanadium-doped layered chromium-copper disulfide crystals

In the work, X-ray and Auger microprobe studies of the surface of crystals prepared from powder samples of CuCr1−xVxS2 disulfides (x = 0÷0.11) by crystallization from melt in the sulfur vapor atmosphere. Sample slabs cut from ingots include crystalline layered blocks with different orientation of copper-containing extended linear inclusions separated by disulfide matrix layers. The results of the microprobe analysis of regions with copper-containing inclusions and the regions adjacent to them are presented.

Photoelectron spectra of powder and single crystalline chromium-copper disulfides

Abstract2p3/2,1/2 Photoelectron spectra of single crystalline specimens of chromium-copper disulfides CuCrS2 and CuCr0.85V0.15S2 are studied. It is shown that the spectra of single crystalline specimens substantially differ from the corresponding spectra of chromium-copper disulfides in the powder state.

Effect of MnO2 on chemical interaction between CaO and Al2O3

We have studied the effect of manganese dioxide (5–20 wt %) on the formation of calcium monoaluminate in the CaO-Al2O3 system during solid-state sintering of five oxide mixtures corresponding to the known calcium aluminates at temperatures from 1100 to 1400°C. X-ray diffraction examination indicated the formation of calcium manganates. The mixture of the calcium manganates melts at 1330°C, promoting the sintering process and the reaction between the calcium oxide and alumina and raising the yield of calcium monoaluminate as the dominant phase. The calcium manganates are shown to be nonreactive with the forming calcium aluminates. The X-ray diffraction results are supported by scanning electron microscopy data for a number of samples.

Thermal transformations of the Cu(dpm)2 complex in inert and reducing atmospheres

The transformation kinetics of the Cu(dpm)2 complex have been studied by thermal analysis under steady-state conditions. The results indicate that, in noncatalytic systems, the dominant process in the temperature range 150–300°C is vaporization of the complex, with an enthalpy of 62 ± 12 kJ/mol. In hydrogen atmosphere on nickel and copper surfaces, responsible for the formation of adsorbed atomic hydrogen, the dominant process is copper reduction. Weight loss data obtained in thermoanalytical runs between 185 and 220°C were used to separate the contribution of the chemical process and to evaluate the apparent activation energies for the hydrogen reduction of copper on nickel and copper surfaces: 32 ± 6 and 48 ± 9 kJ/mol, respectively.