Volume 54, Nº 8 (2018)

High-resistivity zinc selenide crystals containing background impurities have been studied by IR spectroscopy and dielectric spectroscopy. Their IR absorption spectra contain a band attributable to the presence of background Fe impurities in the material. The dielectric characteristics of the ZnSe crystals lead us to conclude that, because of a nonuniform distribution of background impurities, they have the form of matrices containing inclusions.

The crystallization of amorphous Sn-doped TlInS₂ films into three polymorphs has been studied by kinematic electron diffraction. The results demonstrate that the crystallization of 30-nm-thick amorphous films produced by thermal evaporation in high vacuum can be described by the Avrami–Kolmogorov equation: V_τ = V₀[1–exp(–kτ^m)]. Kinematic electron diffraction patterns of the TlIn_1–хSn_xS₂ films have been used to assess the effect of doping with Sn on the growth dimensionality and the activation energy for the crystallization of the amorphous films and the unit-cell parameters of the resultant crystalline materials. Doping extends the temperature range and effective activation energy for the crystallization of the amorphous films.

Tantalum carbide and zirconium carbide powders have been silicided in a gaseous SiO atmosphere at 1400°C. X-ray diffraction and energy dispersive X-ray microanalysis results demonstrate that the silicidation products are Ta₅Si₃ and TaSi₂ in the case of TaC and ZrSi in the case of ZrC. The silicidation rate has been shown to influence the percentages of these silicides in the reaction products. The degree of silicidation reached in this study is about 20% in the case of TaC and about 16% in the case of ZrC.

NASICON-type materials with the compositions Na₃V_2–xAl_x(PO₄)₃, Na₃V_{2 - x}Fe_x(PO₄)₃, Na_{3 + x}V_2–xNi_x(PO₄)₃, and Na₃V_{2 - x}Cr_x(PO₄)₃ (x = 0, 0.03, 0.05, and 0.1) have been prepared and characterized by X-ray diffraction analysis, electron microscopy, and impedance spectroscopy. The results demonstrate that the highest electrical conductivity among the samples studied is offered by the material doped with 5% Fe: Na₃V_1.9Fe_0.1(PO₄)₃. The activation energy for low-temperature conduction in the doped materials decreases from 84 ± 2 to 54 ± 1 kJ/mol and that for high-temperature conduction is ~33 kJ/mol. The discharge capacity of Na₃V_1.9Fe_0.1(PO₄)₃/C under typical working conditions of cathodes of sodium ion batteries has been shown to exceed that of Na₃V₂(PO₄)₃/C. The capacity of the more porous material prepared by the Pechini process (Na₃V_1.9Fe_0.1(PO₄)₃/C-{II}) approaches the theoretical one at a low charge–discharge rate and retains its high level as the charge rate is raised (its discharge capacity was 117.6, 108.8, and 82.6 mAh/g at a discharge rate of 0.1C, 2C, and 8C, respectively).

Using physicochemical characterization techniques and quantum-chemical calculations, we have demonstrated that aluminum chloride has an activating effect on the chemical interaction between sulfur and silica. As a result, we have developed a low-waste process for producing sulfur concrete with good physicomechanical and functional properties.

We demonstrate that a nanoparticulate Sr-substituted carbonate hydroxyapatite can be prepared by fast mechanochemical synthesis, without further annealing of the material. The synthesis process takes 30 min and yields single-phase products. We have obtained a series of Ca1_0–xSr_x(PO₄)₆(OH)₂ samples with x = 0–2.

We have synthesized Ce_xZr_1–xO₂ solid solutions via the thermal decomposition of xerogels of different compositions prepared by drying appropriate hydrosols. The synthesized materials have been characterized by thermal analysis, X-ray diffraction, and Raman spectroscopy. The results demonstrate that the solid solutions are formed at relatively low temperatures (450–600°C). The Ce_xZr_1–xO₂ samples with x = 0.5–0.9 consist of a cubic solid solution. At a lower CeO₂ content (x = 0.2), the material consists of a mixture of cubic and tetragonal phases.

This paper develops an approach to investigation of a solid as an integral system whose fundamental properties are determined by the energetics of its structure. Addressing the subject from a unified viewpoint, we consider the formation, accumulation, and transformations of defects in silicate and aluminophosphate glasses, which emit electromagnetic waves in a wide frequency range as a result of cracking. It has been shown that electron irradiation causes spontaneous electrical discharges, whose magnitude depends on the electron energy and irradiation time. The discharges occur at surface defects. Brush discharges develop in a layer where charged particles are distributed. In a thin layer of a charged dielectric, we observe a breakdown effect. The electrical discharge concentrates at surface defects, which can be produced in advance. A discharge can be initiated by approaching a grounded metallic tip to a charged surface even some time after irradiation. A discharge, mechanical loading, cooling, or heating of glass is accompanied by not only a light burst but also electromagnetic emission (EME), which correlates well with a polymorphic transformation process, thermoluminescence, etc. Thus, the release of accumulated energy from unirradiated and irradiated inorganic glasses on heating and cooling is accompanied by pulsed EME, whose intensity depends on the energy stored in the material.

This paper presents general data on the diorite family: intermediate plutonic rocks in the normally and low alkaline rock subclass. Using quartz diorite from the Altai Mountains as an example, we analyze the feasibility of using methods developed at the Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, for modifying the composition of magmatic and metamorphic rocks for mineral fiber fabrication and stone casting.