Vol 49, No 6 (2023)

Using the ToposPro software package, a combinatorial-topological analysis and modeling of the self-assembly of the following crystal structures with space group I4/mcm are realized: Pu31Rh20-tI204: a = 11.076 Å, c = 36.933 Å, V = 4530.86 Å3, Pu20Os12-tI32: a = 10.882 Å, c = 5.665 Å, V = 670.8 Å3. (Pu4Co)2 (Pu4)-tI28: a = 10.475 Å, c = 5.340 Å, V = 585.9Å3. (Ti4Ni)2(Bi4)-tI28: a = 10.554 Å, c = 4.814 Å, V = 536.2Å3, Bi4-tI8: a = 8.518 Å, c = 4.164 Å, V = 302.15 Å3. For the crystal structure of Pu31Rh20-tI204, 113 variants of the cluster representation of the 3D atomic network with the following number of structural units are established: 4 (14 variants), 5 (61 variants), and 6 (38 variants). A variant of the self-assembly of the crystal structure with the participation of three types of framework-forming polyhedra is considered: K15 = Pu@14(Rh2Pu5)2 with symmetry –42m, double pyramids K10 = (Rh@Pu4)2 with symmetry 4, and octahedra K6 = 0@8(Rh2Pu6) with symmetry mmm and spacers Rh. For the crystal structure of Pu20Os12-tI32, framework-forming pyramid-shaped polyhedra K5 = 0@OsPu4 with symmetry 4, as well as spacers Pu and Os, are defined. For the crystal structure (Ti4Ni)2(Bi4), frame-forming pyramids K5 = 0@Ti4Ni and tetrahedra K4 = 0@Bi4) are defined. For the crystal structure (Pu4Co)2(Pu4)-tI28, frame-forming pyramids K5 = 0@ Pu4Co and tetrahedra K4 = 0@Pu4 are defined. For the crystal structure of Bi4-tI8, frame-forming tetrahedra K4 = 0@Bi4 are defined. The symmetric and topological code of self-assembly processes of 3D structures is reconstructed from clusters-precursors in the following form: primary chain → layer → framework.

Предложена и опробована методика экспериментального определения теплофизических характеристик неактивных алюмофосфатных и боросиликатных стекол методом дифференциально сканирующей калориметрии. Показаны преимущества данной методики измерений. Для стеклоподобных матриц различного состава определены удельная теплоемкость и коэффициент теплопроводности. Полученные экспериментальные значения позволили рассчитать значения температуропроводности. Доказана применимость данного метода при работе с реальными образцами остеклованных высокоактивных отходов для изучения их свойств и формирования на их основе базы данных.

A new method for molecular dynamics (MD) modeling of the glass structure using a crystal structural template is proposed. The template is based on the unit cell of the crystalline phase, whose composition is qualitatively similar to the modeled glass. Using this approach and multistage MD simulation, the model of the spatial structure of grade E borosilicate glass, reproducing its physicochemical characteristics, is obtained. The proposed method enables to model the glass structure using classical MD methods with greater productivity and stability.

Xerogels and powders of a solid solution based on zirconium dioxide are synthesized by the method of coprecipitation of hydroxides from aqueous solutions of salts of zirconium nitrate ZrO(NO3)2⋅2H2O, aluminum Al(NO3)3⋅9H2O, and cerium Ce(NO3)3⋅9H2O with an aqueous 1 M solution of ammonia NH4OH. A dense ceramic with low porosity and water absorption is obtained. The effect of the ultrasonic treatment of the precipitate and mechanical treatment of the xerogel on the physicochemical properties of the obtained materials is evaluated.

The article presents the results of a study of new ceramic materials φ-Bi8Pb5O17 obtained by pyrolysis using mannitol C6H14O6 as a reducing fuel. The values of the band gap of the obtained compositions are determined by analyzing the diffuse reflectance spectra using the Tauc construction. They are in the range from 2.57 to 2.67 eV, which corresponds to visible light photocatalysts. The degree of degradation of methylene orange when using synthesized samples ranged from 95 to 99% when irradiated for 3 h with a fluorescent mercury lamp.

The results of a study of the weather resistance of protective and decorative organosilicate coatings prepared using organosilicate compositions based on polydimethylphenylsiloxane as a binder and hydrosilicates as fillers are presented. The color of the coatings varies due to the use of pigments: natural FeOx minerals of yellow, red-brown, and brown shades of flowers. Using X-ray phase and X-ray fluorescence (XRF) analysis, it is established that the composition of minerals is primarily determined by iron oxides in the crystalline modification of hematite (α-Fe2O3) and goethite (α-FeO(OH)). Pigments contain a small number of impurity compounds of a number of elements that contribute to the color range of the coatings. Organosilicate coatings are exposed for 11 months in the tropical climate of two climatic zones of Vietnam (in the suburbs of Nha Trang and Ho Chi Minh City). The high corrosion resistance and color stability of the coatings are established during the entire test period. According to slight changes in the color and gloss, revealed by spectrophotometric and photoelectric methods, it is shown that higher resistance to solar radiation and other adverse climatic factors is typical for coatings with a brown pigment based on hematite; and the lowest, with a yellow pigment based on goethite.

The stability of synthetic and natural zeolites in model biological media simulating the environment of the stomach (pH 1.8), blood plasma (pH 6.9), and intestines (pH 8) is studied. The effect of long-term exposure (up to 7 days) to biological media on the crystal structure of Beta, Rho, Y, and clinoptilolite zeolites is studied. The degree of degradation of the crystal structure of zeolites is controlled by X-ray phase analysis. Based on the results obtained, conclusions are drawn on the prospects for the use of synthetic and natural zeolites as drug carriers.