卷 69, 编号 8 (2024)

This work reports on the possibility of producing the InGaMgO₄ oxide by two-stage heat treatment of glycine-, starch- and PVA-nitrate precursors. The products formed as a result of their heating at low temperatures (≈ 90°С) were studied by powder X-ray diffraction. It was found that the powder formed from the glycine-nitrate precursor contains nanocrystalline In₂O₃, and drying of the polymer-nitrate compositions leads to the production of a thermally stable X-ray amorphous product. Its' annealing at temperatures above 800°C allows synthesizing InGaMgO₄ powder free of impurity phases. High-temperature treatment of the powder formed from the glycine-nitrate precursor also leads to the production of InGaMgO₄, but does not remove the In₂O₃ impurity. Using scanning electron microscopy, it was found that single-phase InGaMgO₄ powders synthesized from polymer-nitrate precursors have a similar grain structure but differ in grain size distribution. Presumably, this difference is due to the structural features of starch and PVA macromolecules used for the preparation of precursors. The InGaMgO₄ oxide was characterized using differential scanning calorimetry, Raman and diffuse reflectance spectroscopy. The value of its' band gap energy E_g was determined using the Tauc method.

A new approach to prepare highly dispersed calcium aluminate at temperatures from 900°C with desired properties (bulk density starting from 0.015 g/cm³, particle size falling in the range of 7–42 described, which consists of step-by-step heat treatment of a concentrated aqueous solution of Al(NO₃)₃, Ca(NO₃)₂, and C₆H₈O₇ in the molar ratio CaO : Al₂O₃ = 1 : 2. The main stages of the synthesis X-ray powder diffraction, IR spectroscopy, as well as scanning and transmission electron microscopies. dispersed calcium aluminate obtained using the developed approach has pronounced luminescent features.

By the reaction of SbI₃ and iodides of the corresponding cations in organic solvents, two new antimony complexes were obtained — (3-Br-1-EtPy)₃[Sb₂I₉] (1), (1,2-MePy)₄[Sb₈I₂₈] (2). The features of the crystal structure of the compounds were determined by X-ray diffraction. The complexes are thermally stable up to at least 200°C and have a band gap of about 2.2 eV.

Lutetium stannate with a pyrochlore structure was synthesized using solid state reaction route. The heat capacity of the polycrystalline Lu₂Sn₂O₇ in the temperature range 7.99–1871 K was measured by adiabatic and differential scanning calorimetry methods. Entropy, enthalpy change, and derived Gibbs energy were calculated from the smoothed heat capacity data. The Gibbs free energy of Lutetium stannate from simple substances was estimated, using the Δ_fS°(Т) values obtained in this work and the Δ_fH°(Т) values from the literature. The temperature dependence of the cubic crystal lattice parameter and the value of the coefficient of thermal expansion in the temperature range 300–1273 K were determined by high-temperature X-ray diffraction.

Alloys of the GeTe–Bi₂Te₃–Te system, synthesized using a special technique that makes it possible to obtain them in a state as close as possible to equilibrium, have been studied using the methods of differential thermal and X-Ray diffraction analysis, as well as scanning electron microscopy. A solid-phase equilibria diagram, a projection of the liquidus surface, some polythermal sections and an isothermal section at 300 K of the phase diagram were constructed. The fields of primary crystallization of phases, types and coordinates of non— and monovariant equilibria are determined. It has been established that monovariant equilibria on curves emanating from the peritectic and eutectic points of the GeTe–Bi₂Te₃ boundary system undergo transformations at certain transition points. Near the tellurium corner of the concentration triangle, a cascade of invariant transition reactions has been identified, characterizing the joint crystallization of two-phase mixtures of telluride phases and elemental tellurium.

Subsolidus phase equilibria in the La₂O₃–(Ni/Со)O–Sb₂O₅ systems have been studied. A previously unknown compound La₄Sb₂O₁₁ was found in the system La₂O₃–Sb₂O₅. La₄Sb₂O₁₁ has been shown to be decomposed at a temperature of 1060°C to form La₃SbO₇ and LaSbO₄. Two ternary oxides LaNi₂SbO₆ and La₂NiSb₂O₉ were found in the La₂O₃–NiO–Sb₂O₅ system for the first time. These new compounds are stable and do not undergo polymorphic transformations throughout the studied temperature range (25–1350°C). The existence of previously known triple oxides La₃Ni₂SbO₉ and LaNi_1/3Sb_5/3O₆ with structures of perovskite and rosiaite, respectively, has also been confirmed. Two more new compounds LaCo₂SbO₆ and La₂CoSb₂O₉ are formed in the La₂O₃–CoO–Sb₂O₅ system along with previously known compounds with the structures of perovskite La₃Co₂SbO₉, rosiaite LaCo_1/3Sb_5/3O₆ and rhombohedral pyrochlore La₃Co₂Sb₃O₁₄. These compounds are isostructural to those found in the nickel oxide system. The La₂CoSb₂O₉ compound, unlike similar nickel compound, decomposes at a temperature of 990°C. For LaCo₂SbO₆, no thermal effects on DSC curves associated with polymorphic transitions or melting were detected up to 1350°C. Analysis of the optical diffuse reflection spectra of the newly synthesized phases LaNi₂SbO₆, La₂NiSb₂O₉, LaCo₂SbO₆ and La₂CoSb₂O₉ showed that nickel and cobalt in them are in the oxidation state of 2+. Isothermal sections of La₂O₃–(Ni/Co)O–Sb₂O₅ systems at 1050°C have been constructed.

The review is devoted to dispersed powdery porous (including deposited) double and ternary metal alloys. Various approaches to the synthesis of these alloys, as well as modern areas of their practical application are considered. An analysis of the relevance of the study of highly dispersed alloys and the feasibility of developing new methods for their production is presented.

The effect of the ionic liquid 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide on the extraction of U(VI), Th(IV) and lanthanides(III) from nitric acid solutions with phosphorylureas RR'P(O)NHC(O)NHC₈H₁₇ n differing in the nature of the substituents at the phosphorus atom was studied. A significant synergistic effect was discovered during the extraction of metal ions in the presence of an ionic liquid in the organic phase. The stoichiometry of the extracted complexes was determined. The influence of the structure of the extractant, the nature of the organic diluent, and the concentration of HNO₃ in the aqueous phase on the efficiency of the extraction of metal ions into the organic phase is considered.