Glass Physics and Chemistry最新文献

New ceramic materials that have ionic conductivity and can be used as components in various electrochemical devices are being actively developed. This study focuses on the electrical conductivity of a recently prepared layered perovskite-like oxide of La₂BaLu₂O₇, which has a two-layer Ruddlesden–Popper structure. Compounds with this structure exhibit ionic conductivity, whose level depends on the substitutions in the crystal lattice. It is found that the electrical conductivity in La₂BaLu₂O₇ has a mixed oxygen-ionic character, with ionic conductivity accounting for an average of 66.5% of the total conductivity.

Tailings, as industrial waste, have always been unable to be utilized due to the presence of impurities. If the disc granulation technology can be used to process tailings into ceramic products that meet production requirements and can replace coarse aggregate in terms of performance indicators, it will not only solve the problem of huge consumption of coarse aggregate resources, but also solve the problem of recycling tailings as industrial waste. During the granulation process, there are omni-directional integrative (ODI) constraints between the tailings particles, forming a suspended liquid bridge, which consolidates the constraints to form a shape. This article studies the process of adjusting disc granulation and the ratio of raw materials to obtain high-performance ceramic particles, and improves the strength of ceramic particles through secondary processing.

The patterns of formation of geopolymer materials based on aluminosilicates of the kaolinite subgroup (Al₂Si₂O₅(OH)₄·nH₂O) with different particle morphologies using natural platy kaolinite and nanotubular halloysite as an example under conditions of their alkaline activation are studied. It is found that the compressive strength of halloysite-based samples can be 1.4 times higher than the strength of kaolinite-based samples and reach 85 MPa. X-ray diffraction and electron microscopy studies show differences in the phase composition and morphology of the resulting samples depending on the nature of the initial precursor. Nanotube halloysite-based samples geopolymerize over a wide range of SiO₂/Al₂O₃ ratios, which leads to enhanced mechanical strength. Platy kaolinite can recrystallize under alkaline activation conditions into zeolites with A and Y structures, which, accordingly, reduces the mechanical strength of the samples.

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.