Glass Physics and Chemistry最新文献

The mechanochemical activation of zeolite (clinoptilolite and clinoptilolite–stilbite) rocks with acidic salts—sodium hydrogen phosphate and ammonium hydrogen phosphate—with the weight ratio of the initial components of 1 : 1 in an IVS-4 vibratory attritor (1500 rpm, 0.6 kW, specific power 4 W/g, steel grinding set) is studied. The structure, chemical and phase composition, and thermal stability of salt-modified zeolite samples are studied by infrared spectroscopy, atomic emission spectrometry, X-ray phase analysis, and differential scanning calorimetry. The specific volume resistance of pelletized samples is measured using a three-electrode circuit. It is established that the electrical conductivity of high-silica zeolite rocks modified with sodium and ammonium hydrophosphates is 2.2 × 10^–6 up to 2.4 × 10^–5 S m^–1 at 25°C. It is shown that the mechanochemical activation of clinoptilolite and clinoptilolite–stilbite rocks with sodium hydrogen phosphate in a vibratory attritor at a mechanical energy dose of 2.4 kJ/g increases the conductivity of mechanically activated zeolites by factors of 140 and 470 at 25°C, and by factors of 30 and 490 at 100°C, respectively. This allows us to consider mechanochemical activation as a promising method for improving the electrical properties of mineral materials.

An approach is proposed to reduce the stability of the cubic phase of lead selenide by thermal oxidation with atmospheric oxygen and its transformation into an ordered monoclinic phase of lead selenite. An estimated thermodynamic analysis (TA) of the course of possible chemical reactions of lead selenide oxidation with oxygen is carried out. The kinetics of lead selenide oxidation with atmospheric oxygen are studied by X-ray emission analysis, X-ray diffractometry, optical reflection in the infrared region of the spectrum, studies of conductivity in direct and alternating currents, and nuclear magnetic resonance. For the PbSeO₃ structure, the Goldschmidt stability factor was estimated and it was shown that the structure can be classified as perovskite-like and have ferroelectric properties.

The effect of the refractive index n_D and mean dispersion (n_F – n_C) on the nonlinear refractive index of laser and optical glasses for active elements and elements of white optics of high-power pulsed radiation amplifiers is studied. It is shown that the nonlinear refractive index of the studied glasses will not exceed the maximum allowable value of 1.20 × 10^–13 cm²/B² if their refractive index in the green (yellow) region of the spectrum is below 1.550, and the average dispersion is less than 0.00820. It is found that the nonlinear refractive index of the studied glasses depends almost linearly on both the refractive index and the average dispersion. It is proposed that athermal phosphate crowns with a nonlinear refractive index below the specified limiting value can serve as the base for obtaining neodymium glasses with a low nonlinear index.

The possibility of radiation synthesis of luminescent ceramics from a mixture of Ba and Mg fluorides and WO₃ oxide is shown for the first time. Synthesis is implemented in a powerful electron beam with an energy of 1.4 MeV by direct exposure of the charge to radiation. It is shown that the characteristic band is observed in the photoluminescence spectrum of the synthesized materials due to the introduction of tungsten, which indicates the incorporation of tungsten into the lattice during radiation synthesis without the use of additional substances in the charge.

The viscosity of potassium–boron melts is measured in the temperature range 918–1699 K using a vibrational viscosimeter. The content of potassium oxide is varied from 0.74 to 28.46 mol %. The parameters of the viscous flow in melts (the configuration–activation energy(ε_h) and the shifting energy of the bridging oxygen atoms’ bonds (U_∞)) using the configuration–activation model are calculated for two temperature intervals 918–1400 K and 1400–1699 K. The glass transition temperature (T_g) is measured by differential scanning calorimetry (DSC) and the concentration dependence of the glass transition temperature on the content of potassium oxide in the melt is shown.

Using computer methods (ToposPro software package), a combinatorial topological analysis and modeling of the self-assembly of Zr₇₂P₃₆-oS108 (a = 29.509 Å, b = 19.063 Å, c = 3.607 Å, V = 2029.49 ų, Cmmm), Zr₁₈Ni₂₂-tI40 (a = b = 9.880 Å, c = 6.610 Å, V = 645.23 ų, I4/m, and Zr₄Ni₄-oS8 (a = 3.271 Å, b = 9.931 Å, c = 4.107 Å, V = 133.43 ų, Cmcm) crystal structures are carried out. For the crystal structure of Zr₇₂P₃₆-oS108, 40 variants of the cluster representation of the 3D atomic net with the number of structural units 5, 6, and 7 are established. Structural units in the form of a pyramid K5 = 0@PZr₄, tetrahedron K4 = 0@Zr₄, and supratetrahedron K9 = Zr(Zr₄P₄) of four connected tetrahedra. For the crystal structure of Zr₁₈Ni₂₂-tI40 also defined supratetrahedra K9 = Ni(Zr₄Ni₄) are defined. For the crystal structure of Zr₄Ni₄-oS8, the tetrahedral cluster precursor K4 = Zr₂Ni₂ is defined. The symmetry and topological code of the processes of self-assembly of 3D structures from cluster precursors is reconstructed in the following form: primary chain → layer → framework.

Thermoplastic elastomers (TPEs) reinforced with detonation nanodiamonds (DNDs) based on styrene-butadiene rubber are developed. The mechanical characteristics of the reinforced compounds with different DND contents are investigated. The developed material shows a 30% increase in compressive strength compared to the unfilled composite and a 10% increase in the tensile strength of the material with the introduction of 0.1% DND.

With the help of computer methods (ToposPro software package), a combinatorial topological analysis and modeling of the self-assembly of Lu₄Te₄-oF8 (Fm-3m, V = 211.0 ų), Te₄Lu₂₈-oC32 (Cmcm, V = 908.3 ų), Lu₃(TeLu₃)Lu₂-hP9 (P-62m, V = 908.3 ų), and Lu₆₆Te₂₄-mC90 (C12/m1, V = 2467.2 ų) crystal structures are carried out. For the crystal structure of Lu₄Te₄-oF8, cluster precursors K8 = 0@Te₄Lu₄ with symmetry –43m; for Te₄Lu₂₈-oC32, tetrahedral cluster precursors K4 = 0@Lu₄ and K4 = 0@TeLu₃ with symmetry 2 and m; and for Lu₃(TeLu₃)Lu₂, cluster precursors K7 = 0@Lu₃(TeLu₃) with symmetry 3m and spacers Lu are established. For the crystal structure of Lu₆₆Te₂₄-mC90, pyramid-shaped cluster precursors K5 = 0@Lu₅ with symmetry 2, tetrahedra K4 = 0@Lu₄ with symmetry 2, tetrahedra K4 = 0@TeLu₃, and tetrahedra K4 = 0@Te₂Lu₂ are established, and rings K3 = 0@TeLu₂ are involved in the formation of supraclusters-trimers. The symmetry and topological code of the processes of self-assembly of 3D structures from cluster precursors is reconstructed in the following form: primary chain → layer → framework.

The low-temperature heat treatment of K8 glass is carried out at temperatures of 350–500°C in alkaline melts of NaNO₃ and CsNO₃ salts in the field of gamma radiation from the ⁶⁰Co source at the dose rate of 3000 R/s and also outside the field. Under the influence of thermoradiation treatment due to the ({text{Na}}_{{{text{glass}}}}^{ + }) ↔ ({text{Cs}}_{{{text{melt}}}}^{ + }) ion-exchange diffusion, mechanical compressive stresses are created in the surface layer of the glass, which lead to the formation of a waveguide layer of the given thickness and an increase in the refractive index (RI) increment, the number of waveguide modes, and the depth of the waveguide layer.

Molecular dynamics (MD) with ReaxFF potentials is used to study the melting process of quartz and cristobalite together with the amorphous structures obtained at different stages of melting by cooling the melt. The long-term preservation of an excess of eight-membered rings inherited from the crystalline phase is found in the quartz melts, while in the cristobalite melts, the similar preservation of six-membered rings is not observed. Thus, it can be stated that the quartz melts and glasses obtained from them have structural memory, in contrast to cristobalite melts. An increase in the number of four-membered rings with increasing temperature is revealed. A number of other features of the obtained amorphous structures, which we consider as models for glasses, are discussed.