Layered oxygen-deficient double perovskites (ODP) based on the rare-earth elements (REE), barium and 3d-metals (Fe, Co, Cu etc.) are characterized by high values of electrical conductivity and high electrochemical activity in oxygen reduction reaction, and are considered as prospective cathode materials for intermediate-temperature solid oxide fuel cells (SOFC) on the base of proton- and oxygen-ion conducting solid electrolytes (SE). Effective cathode materials should be thermomechanically compatible with materials of SE, which tаkes place when the values of their thermal expansion coefficients (TEC) are close to each other. Due to this the study of thermal expansion of ODP as well as the isotation of different contributions in it (thermal, chemical, spin etc.), is of considerable interest. In this work using dilatometric method the thermal expansion of NdBa_1–xSrxFeCo_0,5Cu0,5O_6−δ (0.0 ≤ х ≤ 1.0) (NBSFCC) ODP was studied using dilatometric method. It was established that the values of average linear thermal expansion coefficient (LTEC) (α) of the samples sharply increased from (15.1–16.2) · 10^–6 K^–1 at Т < 630–920 K to (18.9–23.5) 10^–6 K^–1 at Т > 630–920 K due to the evolution of weaklybonded oxygen from the samples. Values of α in the low-temperature region increase with increasing of values of their oxygen nonstoichiometry index (δ), and in the high-temperature one increase with the x increasing due to the increment of chemical contribution in the samples expansion. Based of the results of dilatometry, thermogravimetry, and iodometry, the thermal and chemical contributions in the expansion оn NBSFCC were isolated, and the effect of crystal structure, cationic and anionic composition of NBSFCC ODP on the values of their thermal and linear chemical expansion coefficient (LCEC, α_δ ) was investigated. It was found, that LCEC values of the samples sharply increased from (8.6–11.8) · 10^–3 at (х < 0.5) to (12.6–15.8) · 10^–3 at (х > 0.5) when transition from ordered tetragonal (х < 0.5) to disordered cubic (х > 0.5) phase took place. It was shown, that dependences of LTEC and LCEC of NBSFCC phases on their crystal structure and chemical compositions obtained in this work are in good accordance with the analogous dependences determined earlier for the ODP of other types.

Based on the published experimental data (phase diagrams of three binary systems, four isothermal sections and DTA curves of 33 alloys), a spatial (three-dimensional – 3D) computer model of the LiCl-PrCl₃-KCl phase diagram has been constructed. It is shown that, in the general case, the diagram is formed by 66 surfaces and 27 phase regions; however, due to the negligible solubility of the initial chlorides and the stoichiometry of the two binary compounds in reality, it consists of 31 surfaces and 14 phase regions. The evaluation of the quality of the obtained 3D model is a comparison of model and initial isothermal sections and calculation of response functions for 33 alloys with temperature values at the boundaries of the primary crystallization regions shown on DTA traces. The geometric structure of the LiCl-PrCl₃-KCl phase diagram is also considered as an illustration of the features of ternary systems of the eutectic type, depending on the nature of the formed in them binary compounds.

Zinc manganite spinel powder specific surface area was found to increase by an order of magnitude via a treatment with sulfuric acid. The specific surface area, determined by nitrogen adsorption, correlates with the specific capacity of zinc manganite spinel positive electrodes. Zinc manganite spinel subjected to a controllable acidic treatment is a promising material for the non-aqueous zinc-ion batteries.

The physicochemical properties of freshly prepared alumophosphate solutions obtained in the Al(OH)₃ – H₃PO₄ – H₂O system with the molar ratio n(Al₂O₃) : n(P₂O₅) = 1.0 : 2.75 have been investigated. The density and temperature dependence of the dynamic viscosity of the studied solutions with a concentration of P₂O₅ 300–485 g/l were studied. The values of the apparent activation energy of the viscous flow (Eη) of alumophosphate solutions are calculated and the concentration range (390–420 g/l P₂O₅) is established, in which Eη is practically constant and is 15.0 kJ/mol. It is suggested that the change in the activation energy of the viscous flow of alumophosphate solutions is due to their structure determined by the composition of aluminum phosphate complexes. The influence of the viscosity properties of alumophosphate solutions and their concentration on the crystallization process of hydrated alumophosphate, in particular, the duration of the induction period and the rate of phase formation, is shown.

Surface properties of the systems based on amines and acrylamide (co)polymers have been studied depending on the molecular structure of the components in aqueous and saline (sodium chloride) solutions. For the systems of amines with an anionic acrylamide copolymer, a change in the shape of the surface tension isotherm was found. The tendency to change the surface properties is enhanced in systems with an anionic acrylamide copolymer, aliphatic amine and in the presence of a low molecular weight electrolyte.

The conditions for functionalization of micro- and nanopowders of aerosil, titanium dioxide and diatomaceous earth by wetting them with a liquid hydrophobic agent (tetraethoxysilane) and giving them fobno/philic properties are investigated. Using infrared spectroscopy, derivatography, scanning electron microscopy, and ξ-metry, the mechanism of tetraethoxysilane interaction with the surface of these powders and their morphology were studied. All powders thus modified are characterized by a non-homogeneous distribution of particles with different aggregation levels: predominantly micrometer-sized particle population (diatomaceous earth), micrometer-sized formation combined with nanoclusters (aerosil, titanium dioxide). Diluted suspensions of functionalized powders in fluorinated varnish were used for hydrophobization of glass, aluminum, and steel surfaces. The highest value of the water wetting edge angle (156°) was observed for aluminum coatings obtained using a composition containing functionalized aerosil.

A preparative method for the synthesis of N-aryl- and pyridine-substituted valine, leucine, isoleucine derivatives by condensation of amino acids sodium salts with benzaldehyde, salicylaldehyde, vanillin, p-chlorobenzaldehyde, 3-pyridinecarbaldehyde and subsequent reduction with sodium borohydride has been developed.

The results of research on the establishment of physicochemical features of acid processing of North African (Moroccan) phosphorites, as well as their influence on the technological process and technical and economic indicators of extraction phosphate acid (EPA) production are presented. Significant differences have been established in the nature of the acid decomposition process, syngony and the size of the formed calcium sulfate crystals for different grades of phosphorites, which is due to a significant influence on the decomposition process not only of the technological mode of the process, but to a large extent differences in the mineralogical composition of phosphate ores. Thus, the increased content of carbonate apatites in phosphorites of the K-9 and K-10 grades led to a higher reactivity in the region of low concentrations. At the same time, the high reactivity of carbonateapatites leads to a number of negative processes, in particular, abundant foaming and passivation of grains of phosphate raw materials with fine-crystalline calcium sulfate precipitate, formed due to the rapid supersaturation of the system, which in turn leads to a sharp decrease in the degree of decomposition. A significant difference in the nature of calcium sulfate crystallization for the conditions for obtaining EPA from the known data was established, which made it possible to conclude that the rate and nature of the process of calcium sulfate recrystallization in the CaO-P₂O₅- H₂O system is determined not only by temperature, sulfate regime and P₂O₅ content in the liquid phase, but also by the nature and composition of phosphate raw materials. Based on experimental data, conclusions were drawn about a decrease in power during the transition from apatite to phosphorites from 21.89 to 24.23% (depending on the brand of Moroccan phosphorite), a significant increase in the load on filters and a decrease of 1.5–2 times in the amount of fluorine compounds released into the gas phase during decomposition.

The article presents data on the production of zinc chloride by autoclave leaching of zinc from zinc concentrate with hydrochloric acid. The influence of the Zn : HCl ratio on the chemical composition of the liquid and solid phases, and the degree of zinc extraction by 28 % hydrochloric acid at a process duration of 10 hours was studied. The liquid phase contains mainly zinc chloride, concentrate impurities, of which calcium, iron, copper, cadmium, and lead predominate, with the their contents of 0.181–0.314 % for calcium and 0.951–1.654 % for lead. The temperature of the leaching process in this case is 65-75°C, the pressure is 1.72 MPa. The recovery rate at these parameters is 71.22–90.10 % depending on the Zn:HCI ratio. The optimal ratio is 1 : 1.1. It has been established that the interaction of zinc concentrate occurs in the kinetic region and continues in the diffusion region, where the duration of the process has a significant effect. The reaction rate constant versus temperature obeys the Arrhenius equation and the average activation energy is 4.05 kJ/mol.

Using published and fund materials, cadastral and topographic maps, terrain plans and field research data, the technogenic transformation, features of the geological environment, of the south, western Belarus area are considered as a result of residential development. It has been established that the geological environment of the region has undergone significant changes by now because of the construction of urban and rural settlements. This manifested itself in the relief restructuring, changes in the composition and structure of cover deposits, in the formation of technomorphic complexes and in the movement of more than 88 million m³ of rocks over various distances. The areas occupied by cities and urban settlements are the most transformed. Within them the volume of technogenically displaced grounds ranges from 0.2 to 20.6 million m³ . The average indicator of the geological environment technogenic transformation per unit area as a result of residential development for the southwestern Belarus is estimated at 3 078 m³ /km².