Vol 43, No 4 (2017)

Founding and determination of thermodynamic functions related to solid often geologic materials is traced showing interactions between Czech Professor F. Wald and Russian N.S. Kurnakov and D.S. Korzhinskiĭ in the early definition of phases and characterization of partly open systems. Development of thermodynamic notions regarding solid-state description is reviewed. For the coupled definition of a mobile component the hyperfree energy was developed and recently put into operation. Novel but somehow unusual term of the associated plutability is explained.

The dependence of the optic properties of niobium-phosphate glasses containing alkali metal oxides on their composition and structural features is investigated. Along with the increase of the niobium oxide content, a shift of the optic absorption boundary to the long-wavelength range and a substantial increase of the refraction index (from 1.50 to 1.73) are observed. The increase of the alkali metal mass results in the decrease of the refraction index and a shift to the short-wavelength range. The correlation between the length of polyphosphate groups and the type of alkali oxide is registered: the chain length increases from lithium to potassium.

The oxide glass system of the composition (10 – x)SrO–xFe₂O₃–90V₂O₅, (x = 0, 2, 4, 6 and 8 mol %) were prepared by a standard melt quenching technique. The amorphous nature of the prepared glass was confirmed using X-ray diffraction technique. The infrared spectra of these glasses were recorded over a continuous spectral range (850–1500 cm^–1). The density of prepared sample was obtained by the Archimedes principle. The physical parameters of the glasses were also determined with respect to the composition. Density increases from 3.10 to 3.20 g/cm³, whereas the molar volume decreases with the increase in Fe₂O₃ concentration. In order to study optical properties, absorption spectra were measured at room temperature. Indirect optical energy band gap, optical dielectric constant, refractive index were calculated from optical energy band gap. The refractive index decreases gradually with the increase in Fe₂O₃ content due to increase of bridging oxygen’s. For temperatures from 300 to 500 K, the dc conductivity increased with the increasing Fe₂O₃ content. The dielectric properties like dielectric constant, dielectric loss factor and dielectric loss tangent investigated at the room temperature in the frequency range of 10 kHz to 1 MHz decreases with frequency. The dielectric behavior shows strong frequency as well as composition dependence.

The details of the formation of CuCl nanoparticles in the sodium alumina-borosilicate glass for different methods of thermal treatment of the samples are studied by exciton thermal analysis. It is revealed that the formation of the CuCl phase in glass depends on the heating rate of the samples to the predetermined temperature of isothermal annealing. The concentration of the nucleating centers of the CuCl phase reaches its peak value at 600°C during slow (60 min) heating up to 650°C, due to the fast increase of the critical size of particles of the phase as a result of the fast temperature increase and the rapid decrease of supersaturation in glass. As a result, the formation of new CuCl nucleation centers terminates above 600°C, and part of the centers formed earlier whose size is less than critical dissolve, which results in the monotonic decrease of the CuCl particle concentration.

The problems of extending cellular glass in the pyroplastic state under a hydrated mechanism of gas formation are considered. It is established that the use of water vapor allows varying the product’s properties over wide limits and get ecologically safe materials. It is shown that the volume of gases released during the reaction and the viscosity of the melt are the factors determining the extension of cellular glass. The kinetic characteristics of the extension of the cellular structure of glass in the thermoplastic state are determined.

In this work a Tm³⁺-doped fluoride glass with good thermal stability is prepared. Intensive 1.8 and 2.3 μm emissions are obtained when pumped by an 800 nm laser diode. And the 1.48 μm emission is limited because of the much strong radiation around 1.8 μm. On the basis of absorption spectrum, radiative properties are investigated and discussed according to Judd–Ofelt parameters (Ω₂, Ω₄, Ω₆) calculated by Judd–Ofelt theory. Besides, absorption and emission cross-sections of ³F₄ → ³H₆ transition are figured out and analyzed by using McCumber and Beer–Lambert theories. The high gain around 1.8 μm was predicted by the large σ_emiτ_rad product (29.8 × 10^–21 cm² ms). The results obtained indicate that the Tm³⁺-doped fluoride glass can be a promising 2.0 μm laser glass material.

Zeolites of a Beta structure with different degrees of substitution of aluminum atoms by those of boron in the aluminum–silicon–oxygen framework have been investigated. The characteristics of the porosity-texture of the fabricated zeolites and the surface properties and sorption capacities of samples to a model drug substance (thiamine hydrochloride) have been examined. It has been demonstrated that isomorphic substitutions could affect the properties of the zeolite under study, whereas the largest effect is associated with the simultaneous presence of aluminum and boron atoms in the zeolite framework. Such samples are characterized with a larger specific area and pore diameters, a high concentration of Lewis acidic sites on the surface, and high adsorption capacity.

The technology of liquid-phase synthesis of mesoporous xerogels and aerogels based on ZrO₂–Y₂O₃–CeO₂ is developed. Xerogels are obtained by the coprecipitation of hydroxides, while aerogels are obtained in accordance with the sol–gel technology: the average pore size is 1.5–17.2 nm and the specific surface area is 120–878 m²/g. Aerogels are characterized by a high degree of porosity: the pore volume attains 1–4 cm³/g. Based on precursor xerogels, nanopowders of a tetragonal solid solution of the (ZrО₂)_0.92(Y₂О₃)_0.03(CeО₂)_0.05 composition with a particle size of 5–9 nm and S_spec = 74 m²/g were fabricated. Due to the high values of their specific surface area, the synthesized xerogels and aerogels are promising as sorbents, catalysts, or catalyst supports.

The phase relationships in the Na₂ZnP₂O₇–LiKZnP₂O₇ system are studied. They are represented by a mixture of the starting components in the subsolidus region. The eutectic was found at a temperature of 640°C and composition of 0.5LiKZnP₂O₇. The phase formation of this system is compared with the previously studied NaKZnP₂O₇–LiKZnP₂O₇ system. It is shown that a structural factor affects the geometry of the state diagrams.