Glass Physics and Chemistry最新文献

The vaporization processes and thermodynamic properties of the Sr_xBa_1 – xAl₂Si₂O₈ (x = 0.1–0.9 in increments of 0.1) system are studied for the first time using high-temperature mass spectrometry (HTMS) at a temperature of 2000 K. The samples are synthesized by the solid-state synthesis method at a temperature of 1623 K with isothermal holding for 5–10 h. The single-phase state and celsian-type structure are confirmed by powder X-ray diffraction data and Rietveld refinement using the MAUD software. Partial pressures of Sr, Ba, BaO, SiO, and O₂ are determined, together with the activities of SrO, BaO, and SiO₂ in the condensed phase, as well as the Gibbs energy of mixing (ΔG) and excess Gibbs energy (ΔG ^E). A negative deviation from ideal behavior is found across the entire composition range, with a minimum in ΔG at x = 0.4 in Sr_xBa_1 – xAl₂Si₂O₈. The obtained results are important for the development of heat-resistant, radio-transparent ceramics based on the (Sr,Ba)Al₂Si₂O₈ system.

The results demonstrate the influence of the mass ratio of CaO/P₂O₅ and the total content of oxides (Na₂O + CaO) in low-silica glasses of the Na₂O–CaO–ZnO–SiO₂–P₂O₅ system on their tendency to crystallization, bioactivity, and the size of the temperature range T_x–T_g, which determines the manufacturability of the glass being studied. The influence of the duration of interaction between the SBF solution and monolithic glass samples is established for the main characteristics used to describe the behavior of glasses in vitro: the pH of the SBF solution, the concentration of calcium ions in this model environment, and the formation of calcium phosphate phases with an apatite-like structure on the surface of the glasses.

In this study, the properties of TiS₃ are investigated as a potential electrode material for electrochemical multivalent Ca- and Mg-ion batteries. Using density functional theory, we carry out calculations to thoroughly study this material. It is found that TiS₃ is the most suitable material for cathodes of Ca-ion batteries. Intercalation of Ca²⁺ cations in TiS₃-based cathode materials turned out to be energetically favorable, with an operating voltage of 1.98 V relative to Ca/Ca²⁺. This result is noteworthy because high-voltage electrodes for multivalent batteries are relatively rare. Diffusion coefficients of Mg²⁺ and Ca²⁺ amounted to 6.59 × 10^–13 and 4.03 × 10^–21 cm² s^–1, respectively. The diffusion coefficient can be further improved by lattice strain engineering and the use of two-dimensional materials. The maximum theoretical capacity values were 618 and 588 mAh/g for Mg_0.5TiS₃ and Ca_0.5TiS₃, respectively. The specific stored energy of Ca_0.5TiS₃ amounted to 1132 W h/kg, which exceeds that of LiCoO₂ (1070 W h/kg), despite its lower electrochemical stability.

This article analyzes the acid–base characteristics of the surface of high-silica quartzoid glasses (QGs) containing cesium, and their interaction with an aqueous environment, which arise from changes in the functional composition of the surface and the desorption of cesium ions. The concentration of surface active centers with pK_a = 5.0, 6.4, 8.0, and 14.2, as well as the dependence of their quantity on the cesium content in the glass and the conditions of QG synthesis, are studied.

Using computational methods (ToposPro software package), a combinatorial–topological analysis and modeling of cluster self-assembly are carried out. The crystal structures Sm₆Pd₁₀Sn₁₁-mS54 (a = 17.386 Å, b = 4.514 Å, c = 16.926 Å, β = 121.38°, V = 1134.46 ų, C2/m) and Sm₃Pd₅Sn₅-mS52 (a = 17.205 Å, b = 4.520 Å, c = 14.206 Å, β = 99.71°, V = 1088.8 ų, C2/m) are studied. For Sm₆Pd₁₀Sn₁₁-mS54, 48 variants for identifying cluster structures with the number of clusters N = 3 (15 variants), 4 (22 variants), and 5 (11 variants) are established. The self-assembly of a crystal structure involving a cluster is considered. Cluster K6-1 = 0@6(Sm₂Sn₂Pd₂) has the form of a double tetrahedron with the center at C1(4e, –1); cluster K6-2 = 0@6(Sm₂Pd₂Sn₂) is a double tetrahedron with the center at C2(4f, –1); cluster K5 = 1Sn@4(Pd₂Sn₂) has the form of two linked three-atom PdSn₂ rings with a common Sn atom at the 2c position with 2/m symmetry; cluster K4 = 0@4 (Pd₂Sn₂) is a tetrahedron with the center at the 4g position with symmetry 2; and cluster K3 = 0@3(SmSnPd) is formed by three atomic rings with the center at the 8j position. For Sm₃Pd₅Sn₅-mS52, 41 variants of identifying cluster structures with the number of clusters N = 3 (21 variants) and 4 (20 variants) are established. The self-assembly of the crystal structure involving a cluster is considered. Cluster K6-1 = 0@6(Sm₂Pd₂Sn₂) is a double tetrahedron with the center at C1(4e, –1); cluster K6-2 = 0@6(Sm₂Pd₂Sn₂) is a double tetrahedron with the center at C2(8j, 1); cluster K5 = 1Sn@4(Pd₂Sn₂) consists of linked PdSn₂ rings with a common Sn atom at position 2a with 2/m symmetry; and cluster K3 = 0@3(SnPd₂) is formed by three rings with the center at position 4h (1/2, 1/3, 1/2). The symmetry and topological code of the self-assembly processes of 3D structures from precursor clusters was reconstructed in the following form: primary chain → layer → framework.

Glasses comprising B₂O₃ as network former, Na₂O and SrO as network modifiers, and ZnO as intermediate component have been synthesized using melt quenching technique. The composition of the prepared glasses is xZnO–10SrO–20Na₂O–(70 – x)B₂O₃ with x = 0, 3, 6, and 9 mol %. Physical and structural properties of the glass samples were evaluated using density and molar volume measurements, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Density and molar volume were determined using the Archimedes principle with benzene as the solvent and their variation with the change in ZnO concentration was observed. XRD analysis confirmed the amorphous nature of the prepared glass samples. The FTIR analysis, carried out in the range of 400–1600 cm^–1, exhibited the various functional groups present in the glass structure. The evaluation of energy band gap and other important optical parameters has been done through UV-Visible spectroscopy. The results from these experimental methods are in good agreement with each other and with the relevant scientific literature.

Hydrophobic materials are ubiquitous in our daily lives due to their water-repellent properties. However, the preparation of many hydrophobic materials involves complex, time-consuming, and environmentally harmful processes. These challenges significantly limit their practical applications. In this paper, epoxy resin was crosslinked with triethylene tetramine to form a gel with a three-dimensional network structure. The gel was modified with fumed silica to create a micro/nano rough structure on the surface. Specialty silicone resin (ST-401) was applied to enhance the environmental stability of the coating. The coating structure, elemental composition, and surface morphology were analyzed and characterized. The hydrophobicity, transparency, self-cleaning, and durability of the coating were tested. The results showed that the epoxy modified SiO₂ coating had good hydrophobicity and transparency, as well as excellent self-cleaning performance, water shock resistance and acid resistance. However, its alkali resistance remains a challenge.

This article presents the results of a study on the effect of the KOH concentration on the formation of potassium titanate nanoparticles containing cobalt under hydrothermal conditions. The synthesis of precursors is carried out by the coprecipitation method, maintaining the ratio of the initial reagents of TiCl₄ : Co(HСОО)₂·2H₂O = 3 : 1, 7 : 1, and 7.25 : 0.75. Subsequent hydrothermal treatment is carried out with solutions with a KOH concentration ranging from 2 to 10 M in increments of 2 M, at temperatures of 180, 200, and 220°C and a pressure of up to 10 MPa. The phase composition and microstructure of the synthesized samples are studied using X-ray phase analysis and scanning electron microscopy. It is shown that at an initial TiCl₄ : Co(HСОО)₂·2H₂O ratio of 7.25 : 0.75 and hydrothermal treatment at 180°C for 24 h, elongated nanoparticles (probably nanotubes or whiskers) with a diameter of about 20 nm begin to form.

Based on synchronous thermal analysis (TGA–DSC), the structural transformations of high-purity synthetic xerogel SiO₂ is studied during heat treatment in various media (argon, air, and oxygen) in the temperature range of 300–1200°C. Chromatography–mass spectrometry and controlled combustion of the sample in a stream of oxygen show that the removal of organic components occurs predominantly in the temperature range of 400–600°C, but continues up to 1050°C. Analysis of porosity, specific surface area, apparent density, and Raman spectra show that in the range of 1000–1200°C, pores are closed and the structural network of the SiO₂ xerogel is compacted with transition to a glassy state.

In this study, organo-inorganic composites based on an epoxy polymer and an FeO-containing oxide pigment are obtained and studied. The structure and morphology of the materials are examined using X-ray diffraction, electron microscopy, optical spectroscopy, and microhardness measurements. It is shown that the composites have a homogeneous structure and contain small (up to 100 nm) particles consisting of various iron oxides (FeO, Fe₃O₄, and α-Fe₂O₃), which exhibit strong absorption of radiation in the near-IR region of the spectrum. The resulting composites exhibit high light absorption in the near-IR spectral region and may be promising as light-absorbing elements in laser systems.