卷 49, 编号 3 (2023)

With the help of computer methods (ToposPro software package), a combinatorial topological analysis and modeling of the self-assembly of Lu4Te4-oF8 (Fm-3m, V = 211.0 Å3), Te4Lu28-oC32 (Cmcm, V = 908.3 Å3), Lu3(TeLu3)Lu2-hP9 (P-62m, V = 908.3 Å3), and Lu66Te24-mC90 (C12/m1, V = 2467.2 Å3) crystal structures are carried out. For the crystal structure of Lu4Te4-oF8, cluster precursors K8 = 0@Te4Lu4 with symmetry –43m; for Te4Lu28-oC32, tetrahedral cluster precursors K4 = 0@Lu4 and K4 = 0@TeLu3 with symmetry 2 and m; and for Lu3(TeLu3)Lu2, cluster precursors K7 = 0@Lu3(TeLu3) with symmetry 3m and spacers Lu are established. For the crystal structure of Lu66Te24-mC90, pyramid-shaped cluster precursors K5 = 0@Lu5 with symmetry 2, tetrahedra K4 = 0@Lu4 with symmetry 2, tetrahedra K4 = 0@TeLu3, and tetrahedra K4 = 0@Te2Lu2 are established, and rings K3 = 0@TeLu2 are involved in the formation of supraclusters-trimers. The symmetry and topological code of the processes of self-assembly of 3D structures from cluster precursors is reconstructed in the following form: primary chain → layer → framework.

The effect of the refractive index nD and mean dispersion (nF – nC) on the nonlinear refractive index of laser and optical glasses for active elements and elements of white optics of high-power pulsed radiation amplifiers is studied. It is shown that the nonlinear refractive index of the studied glasses will not exceed the maximum allowable value of 1.20 × 10–13 cm2/B2 if their refractive index in the green (yellow) region of the spectrum is below 1.550, and the average dispersion is less than 0.00820. It is found that the nonlinear refractive index of the studied glasses depends almost linearly on both the refractive index and the average dispersion. It is proposed that athermal phosphate crowns with a nonlinear refractive index below the specified limiting value can serve as the base for obtaining neodymium glasses with a low nonlinear index.

The viscosity of potassium–boron melts is measured in the temperature range 918–1699 K using a vibrational viscosimeter. The content of potassium oxide is varied from 0.74 to 28.46 mol %. The parameters of the viscous flow in melts (the configuration–activation energy(εh) and the shifting energy of the bridging oxygen atoms’ bonds (U∞)) using the configuration–activation model are calculated for two temperature intervals 918–1400 K and 1400–1699 K. The glass transition temperature (Tg) is measured by differential scanning calorimetry (DSC) and the concentration dependence of the glass transition temperature on the content of potassium oxide in the melt is shown.

The change in the resistive characteristics of lead silicate glasses (LSGs) after treatment in alkaline and acid solutions is studied. It is established that the chemical treatment of glasses and, accordingly, blanks of microchannel plates (MCPs) affects the high-temperature ionic conductivity at a constant activation energy of electrical conductivity. It is shown that the treatment of glasses in NaOH and HF solutions can significantly change the electrical resistance.

The low-temperature heat treatment of K8 glass is carried out at temperatures of 350–500°C in alkaline melts of NaNO3 and CsNO3 salts in the field of gamma radiation from the 60Co source at the dose rate of 3000 R/s and also outside the field. Under the influence of thermoradiation treatment due to the @ ↔ @ ion-exchange diffusion, mechanical compressive stresses are created in the surface layer of the glass, which lead to the formation of a waveguide layer of the given thickness and an increase in the refractive index (RI) increment, the number of waveguide modes, and the depth of the waveguide layer.

The mechanochemical activation of zeolite (clinoptilolite and clinoptilolite–stilbite) rocks with acidic salts—sodium hydrogen phosphate and ammonium hydrogen phosphate—with the weight ratio of the initial components of 1 : 1 in an IVS-4 vibratory attritor (1500 rpm, 0.6 kW, specific power 4 W/g, steel grinding set) is studied. The structure, chemical and phase composition, and thermal stability of salt-modified zeolite samples are studied by infrared spectroscopy, atomic emission spectrometry, X-ray phase analysis, and differential scanning calorimetry. The specific volume resistance of pelletized samples is measured using a three-electrode circuit. It is established that the electrical conductivity of high-silica zeolite rocks modified with sodium and ammonium hydrophosphates is 2.2 × 10–6 up to 2.4 × 10–5 S m–1 at 25°C. It is shown that the mechanochemical activation of clinoptilolite and clinoptilolite–stilbite rocks with sodium hydrogen phosphate in a vibratory attritor at a mechanical energy dose of 2.4 kJ/g increases the conductivity of mechanically activated zeolites by factors of 140 and 470 at 25°C, and by factors of 30 and 490 at 100°C, respectively. This allows us to consider mechanochemical activation as a promising method for improving the electrical properties of mineral materials.

Composite materials based on molybdenum disilicide, boron and aluminum oxide were obtained by heat treatment of mixtures of initial components in the form of finely dispersed powders in air. In the course of chemical reactions, a glass-forming melt is formed, which encapsulates the initial powder particles, which provides increased heat resistance of the composite material. The effect of temperature–time parameters on the phase composition and microstructure of glass–ceramic composites has been determined.

An approach is proposed to reduce the stability of the cubic phase of lead selenide by thermal oxidation with atmospheric oxygen and its transformation into an ordered monoclinic phase of lead selenite. An estimated thermodynamic analysis (TA) of the course of possible chemical reactions of lead selenide oxidation with oxygen is carried out. The kinetics of lead selenide oxidation with atmospheric oxygen are studied by X-ray emission analysis, X-ray diffractometry, optical reflection in the infrared region of the spectrum, studies of conductivity in direct and alternating currents, and nuclear magnetic resonance. For the PbSeO3 structure, the Goldschmidt stability factor was estimated and it was shown that the structure can be classified as perovskite-like and have ferroelectric properties.