Glass Physics and Chemistry最新文献

Using computer methods (ToposPro software package), a combinatorial–topological analysis and modeling of the self-assembly of Yb₄Ni₆Al₂₃-mS66 (a = 15.834 Å, b = 4.069 Å, c = 18.180 Å, V = 1079.47 ų, β = 112.84°, C 2/m, (no. 12), and U₄Ni₅Al₁₈-mS54 (a = 15.547 Å, b = 4.061 Å, c = 16.458 Å, β = 120.00°, V = 899.89 ų, Cm (no. 8) crystal structures are carried out. For Y₄Ni₆Al₂₃-mS66, 85 cluster-structure variants are established: 6 variants with N = 3, 54 variants with N = 4, and 25 variants with N = 5. A variant of the self-assembly of the crystal structure is considered with the participation of clusters K6(–1) = 0@6(Yb₂Ni₂Al₂) and K6 = 0@6(Al₂NiAlAl₂), K4 = @4(YbNiAl2) in the form of a tetrahedron, and K3 = 0@3 (Al₃) in the form of 3 rings, as well as Al spacer atoms. For U₄Ni₅Al₁₈-mS54, 1023 cluster-structure variants were established: 88 variants with N = 4, 485 variants with N = 5, and 442 variants with N = 6. A variant of the self-assembly of a crystal structure is considered with the participation of clusters K6a = 0@6(UNiAl₅), K6b = 0@6(UNiAl₅), and K6c = 0@6(U₂Al₂Ni₂) in the form of paired tetrahedra, and clusters K3 = 0@3(NiAl₂), as well as spacer atoms Ni5, Al3, and Al4. The symmetry and topological code of the self-assembly processes of 3D structures from precursor clusters is reconstructed in the following form: primary chain → layer → framework.

Three borosilicates with the general formula of REE₃BSi₂O₁₀ (REE = Nd, Eu, Gd) were obtained by the high-temperature solid-state synthesis and studied by powder high-temperature X-ray diffraction (HTXRD) in the temperature range from 30 up to 1050°C. The HTXRD study showed that these borosilicates (orthorhombic, Pbca space group) have similar, nearly isotropic thermal expansion in the whole temperature range; the average coefficients of thermal expansion (CTE) were: 〈α_a〉 = 9.6, 〈α_b〉 = 8.3, 〈α_c〉 = 8.7, with α_max – α_min ≤ 1.2 × 10^–6°С^–1. The average volume CTE insignificantly decreases with increasing the cation size from 27.2 for Eu and 27.0 for Gd down to 25.8 × 10^–6°С^–1 for Nd compound while the unit cell volume increases with increasing the REE cation radii in the REE₃BSi₂O₁₀ series.

Exploratory studies are conducted aimed at developing a method for cleaning photocatalytic composites based on porous glass modified with zinc oxide from the organic dye Methylene Blue, with the aim of regenerating them. The effectiveness of using a combined cleaning method (sequential washing with water and ethyl alcohol followed by heat treatment) is demonstrated, ensuring the preservation of the ZnO content in the composite and its sorption properties in relation to Methylene Blue.

The dielectric properties of nanocomposite materials obtained by dispersing Rochelle salt in porous dielectric matrices of zeolites, asbestos, and opals are studied. A nonmonotonic dependence of the Curie temperature on the size of ferroelectric nanoparticles is established.

For mesoporous vitreous matrices and composites based on them—base matrices doped with silver halides (Hal = Cl, Br, I)—the structural parameters (specific surface area, pore diameter, pore size distribution, volume porosity, pore tortuosity coefficient, and structural resistance coefficient) are studied using gas adsorption, liquid filtration, and electrical conductivity methods in 1 : 1 charge electrolyte solutions.

The possibility of obtaining bulk zeolites by alkaline activation and subsequent hydrothermal treatment of natural kaolin grade KR-1 is studied. The alkaline activator is obtained by mixing solutions of water glass and sodium hydroxide. The mass fraction of water glass solution in the alkaline activator is varied from 0 wt % to 90 wt % in 10% increments. Depending on the amount of added liquid glass, amorphous geopolymer materials, as well as bulk zeolites with A and Y structures, are obtained, which is confirmed by the X-ray diffraction (XRD) data. Additional hydrothermal treatment of samples at 140°C in an alkaline medium lead to the crystallization of zeolites with sodalite, faujasite, and zeolite P structures.

Using computer methods (ToposPro software package), a combinatorial–topological analysis and modeling of the self-assembly of Ba₁₁Cd₆Sb₁₂-mS58 (a = 34.082 Å, b = 4.891 Å, c = 13.172 Å, β = 109.63°, V = 2068.20 ų, C12/m1) and Ba₁₁Cd₈Bi₁₄-mS66 (a = 28.193 Å, b = 4.893 Å, c = 16.823 Å, β = 90.84°, V = 2320.55 ų, C12/m1) crystal structures are carried out. For Ba₁₁Cd₈Bi₁₄-mS66, 116 cluster-structure variants are established: 2 variants with N = 3, 36 variants with N = 4, and 78 variants with N = 5. A variant of the self-assembly of the crystal structure is considered with the participation of clusters K3(8j) = 0@3 (BaCdBi) in the form of a ring of 3 atoms; K5(2a) = 0@5(BaCd₂Bi₂) in the form of two rings of three atoms with a common Ba atom; clusters K6(2c, 2/m) = 0@6(Ba₄Bi₂) in the form of paired tetrahedra; clusters K6(2c, 2/m) = 0@6(Ba₂Cd₂Bi₂) in the form of paired tetrahedra; Bi atoms forming a chain; and Bi spacer atoms. For Ba₁₁Cd₆Sb₁₂-mS58, 107 cluster-structure variants are established: 13 variants with N = 3, 39 variants with N = 4, 39 variants with N = 5, and 16 variants with N = 6. A variant of the self-assembly of a crystal structure with the participation of clusters K5(2a, 2/m) = 0@5(BaCd₂Sb₂) is considered in the form of two rings of three atoms with a common Ba atom; clusters K6(4e, –1) = 0@(Ba₄Sb₂) in the form of paired tetrahedra; clusters K6(4f, –1) = 0@(Ba₂Cd₂Sb₂) in the form of paired tetrahedra; six atomic clusters K6(2c, 2/m) = 0@4(Ba₄Sb₂) in the form of paired tetrahedra; Cd and Sb atoms forming a chain; and Sb(4) spacer atoms. The symmetry and topological code of the self-assembly processes of 3D structures from precursor clusters are reconstructed in the following form: primary chain → layer → framework.

The phase transformations and crystalline phases precipitated in powders of quenched glasses similar in composition to Li–aegirine (LiFeSi₂O₆) subjected to heat treatment in the temperature range of 600–1000°C, are studied by differential scaning calorimetry (DSC) and X-ray diffraction analysis (XRD). The formation of a low-temperature metastable hexagonal lithium–iron silicate crystalline phase with a β-quartz structure is demonstrated for the first time. The conditions for obtaining this phase and the electrochemical properties of the developed material are discussed. In the first charge–discharge cycle, the cell containing a crystalline phase with a β-quartz structure as the anode has a specific capacity of ~400 mAh/g, which is more than one-and-a-half times higher than this value for the monoclinic modification of Li–aegirine.

The formation of a biostable protective coating based on acetate complexes of Mn(II) with 1,10-phenanthroline on a wood surface is described. The synthesis of acetate mono-, bis- and tris-chelate complexes of Mn(II) with 1,10-phenanthroline is described, and they are studied using IR spectroscopy and thermogravimetry. For acetate complexes of Mn(II) with 1,10-phenanthroline, their fungistatic activity in relation to Ulocladium sp. fungi is studied. The physical and mechanical properties of new transparent protective coatings on wood, which contain these compounds as active biocidal components, are studied. The transparent protective coatings are two-layer systems with a primary impregnation layer of an active biocidal component—acetate 1,10-phenanthroline complexes of Mn(II)— applied to the wood surface, followed by a second protective layer of organosilicon varnish KO-921 based on polymethylphenylsiloxane resin. The results of atmospheric weather tests of wood samples (pine sapwood) with the applied transparent protective coatings are presented in terms of their ability to prevent biodegradation of wood in the conditions of the tropical savanna climate of the Joint Russian–Vietnamese Tropical Research and Technology Center (Russian–Vietnamese Tropical Center).

This article presents the results of determining the crack resistance of quartzoid glasses (QGs) doped with cesium. Crack resistance is calculated on the basis of measured values of microhardness and Young’s modulus. The relationship of crack resistance with the content of cesium oxide (Cs₂O 0.76–2.11 wt %) in glass is analyzed. The results of measuring ¹¹B and ²⁹Si NMR spectra are used to interpret the effect of the presence of cesium in glass on the ability of the studied material to resist crack formation.