In this paper, we consider modeling of the hydration kinetics of β-CaSO4⋅0.5H2O with the use of conductometric measurement results. We review existing kinetic models and use them to describe the results obtained. Stochastic models are shown to ensure the best agreement with experimental data. The practically important result of this study is the possibility of predicting the setting time of gypsum plaster mortars.

The crystal–melt phase transition of a synthesized polycrystalline Ge2Sb2Te5 material (sp. gr. P $$\bar {3}$$ m1) has been studied using differential scanning calorimetry, thermogravimetry, and temperature-dependent electrical resistance measurements in the range from room temperature to 750°C. Characteristic temperatures of the melting process and the enthalpy of fusion of this material have been determined, and its melting has been classified as a semiconductor–semiconductor phase transition. The conclusion has been made that the predominantly covalent component of interatomic interaction in the crystalline material remains unchanged upon melting.

The tellurium, molybdenum, and zinc complex oxides Te2MoO7 and ZnTeMoO6, promising starting materials for the preparation of zinc-containing tellurite–molybdate glasses, have been synthesized by heating accurately weighed amounts of orthotelluric acid and ammonium heptamolybdate and zinc nitrate crystal hydrates and identified by X-ray diffraction. Using reaction calorimetry, the standard enthalpies of formation of the complex oxides have been determined to be −1412.9 ± 23.7 and −1469.4 ± 23.2 kJ/mol, respectively. These values have been calculated as the difference between the standard enthalpies of solution of the complex oxides and mixtures of constituent binary oxides of corresponding content in concentrated hydrochloric acid and a concentrated sodium hydroxide solution.

Needlelike and faceted platelike bulk Cd3As2 crystals record large in weight (up to 25 g) and size have been grown by chemical vapor transport in a vertical configuration. Mass transport and growth rate calculations based on data on Cd and As4 vapor partial pressures have been used to optimize experimental conditions. The quality of the crystals was assessed by X-ray diffraction. The single crystals obtained have been used for detailed magnetotransport measurements at temperatures from 80 to 300 K in magnetic fields of up to 1 T. The results demonstrate that the temperature dependence of the resistivity of the grown cadmium arsenide crystals exhibits metallic behavior, with a well-defined linear contribution to their magnetoresistance, whose magnitude reaches 135%/T at 80 K. At the same time, the carrier concentration evaluated by Hall effect measurements proves to be noticeably lower than the level typical of polycrystalline Cd3As2. The linear magnetic field dependence of resistivity and the appreciable magnitude of this effect are of practical interest for the use of Cd3As2 crystals as materials of magnetic sensors.

In this paper, we report the preparation of titanium carbide from mineral concentrate by plasma synthesis, without chemical isolation of TiO2, a major oxide component. Chemical and phase analysis data for synthesis products are used to discuss chemical reactions occurring during plasma treatment of a starting mixture of the concentrate and a carburizer. We describe a model for the destructuring of mixed compounds in the mineral concentrate and synthesis of titanium carbide. As a local power source, we use an experimental setup comprising an indirect electric arc plasma source and microwave generator. The specific enthalpy of the plasma jet reaches ~3 kJ/g at a weight-average velocity of up to 10 m/s, and additional exposure to a microwave field makes it possible to raise the plasma energy and process temperature. In this manner, high-purity stoichiometric titanium carbide has been prepared. Plasma processing has been demonstrated to be a promising approach for the preparation of titanium carbide nanoparticles from titanium-containing mineral concentrates.

Fe:ZnSe single crystals are promising materials for mid-infrared (4–5 μm) lasers. Here we present thermodynamic analysis of the vapor phase growth of Fe:ZnSe single crystals by a modified free growth method. Doping with Fe atoms was performed during the growth process. The single crystals were grown from sublimates of the binary compounds ZnSe and FeSe placed in separate source compartments. Vapors of the starting materials were directed to a single-crystal seed in the growth zone through calibrated orifices. Calculations were performed for physical transport in a helium atmosphere. We took into account three main steps of the growth process: vaporization of the starting materials in the source compartments, transport of the vapor to the growth zone, and crystal growth on the seed. The rate of the growth process was assumed to be limited by mass transport from the source to the growth zone, controlled by the geometric dimensions and mutual arrangement of the elements of the growth ampule. The experimental data on the dopant concentration are compared to the calculation results. The proposed growth technique is shown to ensure preparation of single crystals up to 8 cm3 in volume, with a Fe concentration of up to 5 × 1018 cm–3.

Regenerative medicine approaches require the creation of new types of resorbable inorganic materials for use in bone tissue engineering. This review considers magnesium-based materials, including magnesium phosphates, which are characterized by a high dissolution degree in the body environment, and their prospects for creating implants for the treatment of bone tissue defects, including cements, ceramics, and composite scaffolds.

AlGaInSbP quinary solid solutions have been synthesized for the first time on InP substrates via temperature-gradient zone recrystallization. We have carried out thermodynamic analysis of the solid solutions, determined their composition, assessed their structural perfection, and measured their photoluminescence spectra. Thermodynamic analysis of the AlxGayIn1–x–ySbzP1–z solid solutions has shown that they have constant lattice parameter in the ranges 0.01 ≤ x ≤ 0.3, 0.0 ≤ y ≤ 1.0, and 0.0 ≤ z ≤ 0.6. In the composition region 0.0 ≤ x ≤ 0.1, 0.0 ≤ y ≤ 1.0, and 0.2 ≤ z ≤ 0.7, the solid solutions are prone to spinodal decomposition. Using linear interpolation methods, we calculated parameters of heterophase equilibria in the AlxGayIn1–x–ySbzP1–z–InP system in the regular solution approximation and located the composition regions of direct (Г8 → Г5) transitions (x = 0.1, 0.0 ≤ y ≤ 0.9, and 0.0 ≤ z ≤ 1.0) and indirect (Г8 → X5) transitions (x = 0.1, 0.5 ≤ y ≤ 0.9, and 0.0 ≤ z ≤ 0.7). AlGaInSbP epitaxial layers grown at temperatures in the range 773 ≤ T ≤ 973 K, temperature gradients in the range 10 ≤ G ≤ 80 K/cm, and molten zone thicknesses in the range 100 ≤ l ≤ 300 μm had a surface roughness of ~6 nm and high structural perfection (BH/2 ≈ 10″).

This study presents the results of an investigation into the hot pressing of optical magnesium oxide (MgO) ceramics from powders synthesized via the self-propagating high-temperature synthesis (SHS) method. A preprocessing technique for industrially produced raw materials is proposed to adjust their impurity composition to a level sufficient for obtaining high-quality optical ceramics. The addition of 1 wt % LiF as a sintering aid to the SHS precursor enables the fabrication of MgO ceramics with a thickness of 1.5 mm, achieving near-theoretical transmittance across the material’s transparency range (0.2–9.5 µm). It is demonstrated that even a small amount of LiF (as low as 0.125 wt %) significantly enhances the transparency of the ceramics; however, it also leads to a substantial reduction in thermal conductivity within the studied temperature range (25–300°C). The thermal conductivity of MgO ceramics without the sintering aid is measured at 67.7 W/(m K) at room temperature. The microhardness of the fabricated ceramic samples remains largely unaffected by the LiF content in the precursor, with values ranging from 9 to 11 GPa.