Glass Physics and Chemistry最新文献

The atomic radial distribution function of vitreous AgGeAsSe₃, obtained based on the experimental intensity curves taken with monochromatic copper and molybdenum radiation, is interpreted using a fragmentary model in the entire ordering region (~9 Å). It is shown that the glass consists of selenium and selenium-arsenic tetrahedra with germanium and silver atoms inside. The spatial arrangement of such tetrahedra in glass within the ordering region is similar to their arrangement in the GeAsSe and GeSe₂ structures. It is proposed that the “openwork” structure of the fragments of these structures allows the movement of Ag⁺ ions (ionic conductivity) in vitreous AgGeAsSe₃. Fragments of the structure of the ion-conducting compound Ag₂Se are not found in the studied glass.

A first principle study was performed to investigate the electronic and thermostructural properties of the Ti₂AlC MAX-phase using quasi-harmonic Debye approximation. The thermodynamical properties of Ti₂AlC MAX-phase at various temperatures and pressure were calculated via the quasi-harmonic Debye approximation and explored the role of temperature and pressure on heat capacity, bulk modulus, thermal expansion coefficient, Debye temperature, enthalpy, entropy, and Gibbs free energy. Surprisingly, both the bulk modulus and Debye temperature was observed to drop with increase in temperature. However, a rise in both occurred as the pressure gradually builds up. This suggests that the heat capacity is influenced by pressure and temperature in opposing ways. The observation of increase in both heat capacities (C_p and C_v) due to increase in temperature infers an increase in the thermal velocity of the atoms. Consequently, the thermal velocity of the atoms decreases with a decrease in pressure which affects C_p and C_v, respectively. In addition, the Gibbs free energy slope increased at a little rate at constant pressure. These novel results possessing improved thermostructural properties could be useful for high-temperature fatigue-resistant applications specially in a gas turbine engine.

A method for reinforcing a compound based on styrene-butadiene thermoplastic elastomer has been developed. The mechanical characteristics of reinforced compounds have been studied. A comparative analysis of various methods for introducing a nanofiller into a polymer matrix has been carried out. The developed technique shows an increase in the compressive strength of the composition by 50%, as well as tensile strength by 20%.

Utilizing mining and metallurgical waste as a resource is one of the effective methods to tackle the issue of solid waste accumulation. In this study, the CaO–MgO–Al₂O₃–SiO₂ system glass–ceramics were prepared based on the traditional melt-casting technique using iron ore slag as the main raw material. Investigations were done on how different iron ion concentrations affected glass–ceramics properties. And the migration pattern of iron ions was explored deeply using Raman spectroscopy and FTIR. XRD revealed the crystallization ability of augite and magnetite increasing as the iron ions grew. The combination of vibrating sample magnetometer, electron backscatter diffraction, and MFM techniques indicates that the distribution of magnetite, grain size, and structure are connected to the magnetic performances of glass–ceramics. Glass–ceramics has outstanding magnetic properties and flexural strength. Therefore, it has vast potential for future development in electronic devices, wear-resistant applications, and electromagnetic shielding.

A method is proposed for increasing the resistance of a superhydrophobic coating based on a CNT xerogel to frost deposition through the use of decorating nanoparticles. The effects of the addition of fullerenes, carbon nanoonions (CNOs), detonation nanodiamonds, silicon dioxide, and paraffin to the xerogel are tested. An increase in the resistance of the coating to the deposition of condensate in the form of frost is revealed. The addition of fullerene C₆₀ leads to the best results. Increasing the resistance to icing allows us to spend less power on heating the surface during short cold snaps, bypassing the anti-icing properties of the protective superhydrophobic layer. However, the application of this approach shows a deterioration in the resistance of the coating to the penetration of the spray. This is given a qualitative explanation and measures to combat it are proposed. No effect of the additives on the mechanical properties of the coating or its resistance to damage is detected. In additon, decorating additives affect the formation of the coating relief. With this, it is possible to influence the stochastic processes of the formation of roughness during the drying of the xerogel.

Using computer methods (ToposPro software package), a combinatorial topological analysis and modeling of the self-assembly of the following crystal structures are carried out: Y₂₀Cu₂₀Mg₆₄-oC104 (a = 4.136 Å, b = 19.239 Å, c = 29.086 Å, V = 2314.45 ų, Cmcm), Y₂₀Cu₂₀Mg₅₂-oC92 (a = 4.097 Å, b = 19.279 Å, c = 25.790 Å, V = 2037.30 ų, Cmcm), and Y₃(NiAl₃)Ge₂-hP9 (a = b = 6.948 Å, c = 4.156 Å, V = 173.78 5 ų, P-62m). For the Y₂₀Cu₂₀Mg₆₄-oC104 crystal structure, 52 variants of the cluster representation of the 3D atomic network with the 3, 4, and 5 structural units are established. Four crystallographically independent structural units in the form of a tetrahedron are determined: tetrahedron K4 = 0@CuMg3, tetrahedron K4 = 0@YMg3, tetrahedron K4 = 0@YCuMg₂, and a supratetrahedron K6 = 0@YCu2Mg3. A variant of self-assembly with the participation of hexamers from six linked structural units is considered (K4B+ K4C)(K4A+ K6)(K4B+ K4C). For the Y₂₀Cu₂₀Mg₆₄-oC92 crystal structure, 27 variants of cluster representation of the 3D atomic mesh with 3, 4, and 5 structural units are established. Three crystallographically independent structural units in the form of a tetrahedron are determined: tetrahedron K4 = 0@YCuMg₂, cluster K6 = 0@6(Y₂Mg₄) in the form of double tetrahedrons YMg₃, and a nine-atom supratetrahedron K9 = Mg@Y₂Cu₂Mg₄ consisting of two YMg₂Cu and two YMg₃ tetrahedrons. A variant of the self-assembly involving trimers of three structural units K4+ K6+ K9 is considered. For the Y₃(NiAl₃)Ge₂-hP9 crystal structure, eight variants of decomposition of the 3D atomic mesh into cluster structures with the participation of two structural units are established. A variant of the self-assembly with the participation of packing generatrices of seven-atom clusters-precursors K7 = 0@Y₃(NiAl₃) with the participation of Ge atoms-spacers is considered. The symmetry and topological code of the self-assembly processes of 3D-structures is reconstructed from clusters-precursor in the following form: primary chain → layer → framework.

Nanosized precursor powders of (1 – x)ZrSiO₄‒xZrO(OH)₂ are synthesized by the sol-gel method with the separate precipitation of components to obtain (1 – x)ZrSiO₄‒xZrO₂ ceramic composites. The thermal behavior of precursor powders is studied by differential scanning calorimetry and thermogravimetry (DSC/TG). Ceramic composites with a high level of microhardness are obtained by sintering powders, preliminarily calcined at 850°C, in air in the temperature range 1000‒1300°C. In the future, such ceramic composites can be used as matrices for solidification and isolating high-level waste (HLW).

Crystals of a novel hybrid organo-inorganic borate, K[B₅O₆(OH)₄][B(OH)₃]₂(H₂O)(C₁₀H₂₀O₅)₂ (1), were obtained from aqueous solutions and characterized by single-crystal X-ray diffraction and IR spectroscopy. 1 is triclinic (a = 10.1567(4), b = 11.9941(6), c = 17.1893(9) Å, α = 75.280(4), β = 79.406(4), γ = 88.531(4)°, V = 1990.270369 ų, SG P-1; R₁ = 0.058). Its structure contains [K(C₁₀H₂₀O₅)₂]⁺ groups which behave as “hydrophobic” templates for the inorganic part comprised of ({{{text{B}}}_{{text{5}}}}{{{text{O}}}_{{text{6}}}}left( {{text{OH}}} right)_{4}^{ - }) anions and neutral B(OH)₃ molecules.

This paper discusses the technology of formation of photoresistive structures based on a composite of lead selenide and lead selenite. The structures are formed by the oxidation of n-PbSe polycrystalline films. Film The surface modification mechanism of n-PbSe films in the oxidation process is analyzed by a Zeiss Merlin scanning electron microscope (SEM). The new results of the authors on the oxidation mechanism of n-PbSe, together with their earlier publications, are summarized and their consistency with each other is examined. A theoretical model (hypothesis) of the potential profile of a photosensitive heterojunction is proposed, in which each crystal of the n-PbSe film during oxidation in an atmosphere of dry air forms a continuous shell on the p-PbSeO₃ surface. The hypothesis on the structural model of the photosensitive heterojunction proposed by other authors, which is based on the oxidation mechanism proposed by us, is practically confirmed in this study.