Inorganic Materials: Applied Research最新文献

Theoretical calculations on the nonlinear optical properties of nematic liquid crystals are presented, investigated using the polarization-optical method (POM) and differential scanning calorimetry (DSC). It was shown that, depending on the time scale, different processes induce a nonlinear optical response. It was discovered that, on the millisecond time scale, the source of the nonlinear optical response is thermal and depends, among other factors, on the main parameters that exclude mesophases, such as temperature and relative composition. It was suggested that the coupling of bonds and conformational changes play a significant role in these processes. It was established that, in the studied liquid crystals, the nonlinear response on the millisecond time scale has a thermal origin and depends on the specific mesophase, the relative concentration of components, and temperature. The deviation from the phenomenological Beer-Lambert law suggests the existence of interaction between the micelles and magnetic particles, the nature of which is still not fully understood.

The interaction between uranium dioxide granules and hydrogen fluoride has been studied, including: thermodynamic evaluation was given, the reaction mechanism was proposed using the model of reactive “shrinking core,” laboratory experiments on fluorination of uranium dioxide granules with hydrogen fluoride gas were performed.

Metal and metal oxide nanopowders synthesized via cryochemical technologies are distinguished by their absence of toxic reagents, solvents, and stabilizers, rendering them well-suited for biomedical applications. In this article, the cryochemical approach—cryogenic precipitation of silver and zinc as carbonates and their subsequent thermal decomposition—is used to produce highly dispersed silver and zinc oxide powders. The size of the obtained nanoparticles is 1–7 nm for silver and 7–17 nm for zinc oxide. Obtained nanoparticles and their precursors were characterized by X-ray diffraction, FTIR-, UV-spectroscopy, and TEM methods.

studies have been conducted on changes in fatigue and long-term strength of samples made of materials ВТ-1, ВТ-3, ВТ-6, ВТ-8, ВТ-9, 20Х13, 40Х13, 12Х18Н9Т, 08Х18, steel 45, steel 30.

The dependence of the potential barrier height at the metal/polymer interface on the number of elastic deformation cycles of the metal was studied. The objects of the study were structural steel and a wide-bandgap dielectric polymer from the poly(arylene phthalide) class, poly(diphenylene phthalide). It was found that the dependence has a complex form with a periodic component. With a relatively small number of deformation cycles, a sharp decrease in the barrier height is observed, and then small fluctuations. The barrier height increases as the number of cycles approaches the threshold value at which the sample fracture occurs. Immediately before the fracture, a sharp decrease in the potential barrier height is observed. In this case, the polymer film can transition to a state with high conductivity. That is, electronic switching occurs. The absolute change in the barrier height was ∼250 meV, and the change in resistance from 2 to 6 orders of magnitude, which can be used to develop a method for non-destructive testing of the state of metals.

The issue of pore formation in the process of impregnation with a low-viscosity binder of the reinforcing layer of silica thread K11S6–170BA–100% satin weaving with a linear density of 170 tex is considered with a breaking load of at least 34.3 N (3.5 kgf). The mathematical apparatus necessary for the development of impregnation technology is considered in order to determine the optimal method of impregnation, which affects the type and size of the pores formed during the impregnation process. An assessment of capillary forces depending on the architectural parameters of the woven filler is carried out. The optimal interval of impregnation rates of the reinforcing layer during transfer molding of a product made of polymer composite material is determined, which makes it possible to minimize pore formation in the structure of the resulting laminate, which proceeds without the release of low-molecular reaction products, which makes it possible to reduce the porosity of the resulting part. The hardware and software complex was used to obtain results on the degree of impregnation of harsh cotton fabric without intensifying action.

The results of studying the possibilities of extracting strategic metals (Au, Ti) from gold-ilmenite placers located in the south of the Russian Far East are presented in this article. The need to apply hydrofluoride techniques in order to create a basis for technology to enrich titanium-bearing deposits is justified. The experience gained through the deep processing of gold ilmenite mineral resources will help us to identify ways to develop complex deposits in the Russian Far East in accordance with the principles of sustainable use of natural resources and environmental protection.

Study of the interaction of uranium dioxide granules, having different histories of origin, with hydrogen fluoride, the necessity of preliminary reduction of uranium oxides before conversion was substantiated.

This article considers issues related to the development of technology for producing gallium nitride templates with a reduced dislocation density on a sapphire substrate. The authors assembled and launched a complex of MOCVD equipment and set up control systems for the growth of in situ structures. Optimum technological modes for the step-by-step production of gallium nitride buffer layers on a sapphire substrate have been developed. These modes include substrate preparation by annealing and nitridation, growth of gallium nitride nucleation layers with their subsequent annealing, coalescence of a single-crystal layer, formation of a buffer layer with the required thickness, properties and doping levels based on various technological approaches to the formation of the nucleation layer. Experimental samples with a smooth, planar surface were obtained: with a pulsed supply of trimethylgallium, the thickness of the grown layer was 2.7–2.8 μm at a growth rate of 1.1 μm/h, full width at half maximum of the diffraction peak is 570 arcsec, the dislocation density is 2.7 × 10⁷ cm^–2; with a continuous supply of trimethylgallium, the thickness of the grown layer was 2.7–2.8 μm, the growth rate was 2.8 μm/h, full width at half maximum of the diffraction peak of 608 arcsec, the dislocation density was 5.1 × 10⁷ cm^–2, the electrical properties of this material were: n-type, carrier concentration was n = 1.0 × 10¹⁷ cm^–3, carrier mobility μ = 113 cm/Vs. Good correlation is observed between the results of thickness and surface morphology studies on SEM and in-situ structure growth monitoring systems. It is shown that the obtained samples in defect density and basic characteristics correspond to commercial templates of gallium nitride grown on sapphire substrate, presented in the world market.

A comparative study was conducted on four different bioactive glass compositions: 45S5, 52S4.6, two variants of 52S4.6 with varying weight percentages of magnesium oxide (MgO, 2.5 and 5.0), and a control group. The degradation rates and effects of these materials on pH levels in simulated body fluids were investigated, as well as the cytotoxicity and cellular proliferation of these materials using an adenocarcinoma cell line. The results showed that 52S4.6 bioactive glass, especially when doped with magnesium, had lower toxicity and a slower degradation rate compared to 45S5 bioactive glass. In addition, this type of bioactive glass had a weaker alkalinizing effect on biological media, suggesting that it may be more suitable for regenerative medicine and tissue engineering applications. In addition, magnesium-doped glass variants have been found to be more suitable for bone and dental surgery due to their ability to promote cell growth.