The ternary NaClO3-C2H5COCSSNa-H2O system was investigated in detail from a physicochemical perspective. During the study, the system was subdivided into binary subsystems and analyzed along six internal sections. Polythermal solubility data were obtained over the temperature range from -23.2 to 38.0 degrees C, and a comprehensive polythermal solubility diagram of the system was constructed. The resulting diagram provides a complete representation of the temperature-dependent solubility behavior of the system components. Based on the constructed phase diagram, the crystallization fields of ice, NaClO3, and C2H5COCSSNa were identified, and the boundaries between them were established. The results indicate that the system belongs to a simple eutonic type. This behavior demonstrates that the components crystallize independently without undergoing mutual chemical interaction, thereby preserving their individual identities. Furthermore, both salts exhibit high solubility in water, and the formation of stable solutions over a wide concentration range was observed within the system. Along the [40% NaClO3 + 60% H2O]-[C2H5COCSSNa] section, the physicochemical properties of solutions prepared at various ratios were comprehensively analyzed. In particular, the crystallization temperature, viscosity, density, pH of the medium, and refractive index were determined as functions of composition. The results demonstrated that variations in component concentration significantly influence the structural state of the solutions. Based on the experimental data obtained, a "composition-property" diagram was constructed. This diagram clearly illustrates the relationship between solution composition and its physicochemical properties and plays an important role in evaluating the practical application potential of the system. The findings may serve as both a theoretical and practical basis for the application of aqueous systems based on NaClO3 and C2H5COCSSNa in technological processes.
Phase equilibria in the La2O3-Lu2O3-SrO (0-50 mol %) system were studied in the subsolidus region up to 1400 degrees C. The aim of the work was to triangulate the system and search for new phases. High-temperature synthesis of samples, X-ray phase analysis, and vibrational spectroscopy were used for the analysis. A continuous series of solid solutions with the perovskite structure of the composition La1-xSrxLuO3-delta, where x = 0-0.15, delta is nonstoichiometry, and a region of solid solutions based on SrLu2O4 crystals is found. The region is bounded by the following point coordinates (mol %): La2O3, 0-15; Lu2O3, 28-50; SrO, 50-70. It was found that the volume of the La1-xSrxLuO3-delta crystal lattice increases with increasing x. The obtained data on phase equilibria in the La2O3-Lu2O3-SrO system are comparable to those for binary confinement systems. IR and Raman spectra of the solid solutions were recorded, and OH groups trapped in the crystal lattice of La1-xSrxLuO3-delta solid solutions were detected. The results of this study can be used in the creation of new materials.
Within the framework of the cluster approach using the 6-311G(d,p) basis set and the hybrid density functional wB97XD, the structure of various variants of the bimetallic ammonia-borohydride complexes MgAl(BH4)5 & centerdot;6NH3 and Mg2Al(BH4)7 & centerdot;6NH3 was simulated. It was found that the MgAl(BH4)5 & centerdot;6NH3 system possesses a wide range of configurations with similar energies and different structures. Most of these complexes contain borohydride anions, which are not part of the first coordination spheres of the metals and have high negative charges. It can be expected that the increase in negative charges on individual anions and the flexibility of the geometric structure will contribute to a reduction in potential barriers to the elimination of H2 molecules. No such features were observed in the Mg2Al(BH4)7 & centerdot;6NH3 systems; the ratio of the number of H atoms in the borohydride and ammonia fragments is far from optimal. Therefore, these complexes are less promising as chemical sources of hydrogen compared to MgAl(BH4)5 & centerdot;6NH3.
The Y2OSe2 and Y2O2Se phases should be considered as candidate phosphor and functional ceramic hosts. More than 20 samples have been studied in the Y2Se3-Y2O3 system and characterized by X-ray powder diffraction (XRD), differential thermal analysis (DTA), visual thermal analysis (VTA), scanning electron microscopy (SEM), microstructure observation (MS), and microhardness measurements. A phase diagram of the Y2Se3-Y2O3 system has been designed for the first time using physicochemical analytical methods. Four invariant phase transformations occur in the system. The Y2OSe2 phase is orthorhombic (Pnma), has the microhardness H = 490 +/- 30 HV, and melts incongruently at 1470 +/- 15 degrees C to form Y2O2Se crystals and a melt. The Y2O2Se phase is trigonal (P-3m1), has the microhardness H = 780 +/- 25 HV, and melts congruently at 2000 +/- 20 degrees C. Two eutectic points exist in the system: (1) 0.505Y2Se3 : 0.495Y2OSe2 (16.5 mol % Y2O3), melting at 1350 +/- 10 degrees C; and (2) 0.615Y2O2Se : 0.385Y2O3 (79.5 mol % Y2O3), melting at 1790 +/- 20 degrees C. The Y2Se3, Y2OSe2, and Y2O2Se phases have similar morphologies in powders and in melt-crystallized primary crystals. The liquidus line of the system has been calculated by the Redlich-Kister polynomial and verified by thermoanalytical experiments.
- In the present work, partial substitution of zirconium cations by magnesium has been carried out in the structure of the silicophosphate Na3Zr2Si2PO12 according to the generally accepted formula Na3 + 2yM(II)yZr2-ySi2PO12, in which charge compensation is achieved through additional Na+ ions. The dopant concentrations in the precursor have been varied in the range from 5 to 20 mol %. It has been shown that in the unit cell of Mg-doped compositions, the group of (SiO4)4- + Na+ ions is partially replaced by (PO4)3-. Silicophosphates with the structure Na3MgyZr2 - ySi2 - 2yP1 + 2yO12 are formed. Therefore, the precursor of composition Na3 + 2yM(II)yZr2 - ySi2PO12 contains excess concentrations of sodium and silicon relative to the forming Mg-substituted NASICON solid solutions. These excess amounts are responsible for changes in the crystal structure and morphology of the ceramics, namely: they increase the unit cell parameters of the crystal structure and give rise to an amorphous or impurity crystalline phase depending on the dopant concentration.
