Russian Journal of Inorganic Chemistry最新文献

Hydride phases based on d-metal-doped TiCr-alloys with the C14 Laves phase hexagonal structure were prepared. Hydride phases with an expanded C14 Laves phase structure and face-centered cubic (FCC) phases known from related literature were identified by X-ray diffraction in the prepared samples. The discovered FCC hydride phase was stable under ambient conditions, and after hydrogen desorption its lattice was transformed to a body-centered cubic (BCC) lattice. The lattice expansion in both TiCr-alloy structures correlates with the volume effects of the individual constituent metal hydride lattices.

Substitutional solid solutions Zn_2–2xNi_2xSiO₄ (willemite structure), Ni_2–2yZn_2ySiO₄ (olivine structure), and Ni_1–zZn_zO (rock salt structure) were prepared by solid-phase synthesis in air, and their extents were determined. Subsolidus phase equilibria in the NiO–ZnO–SiO₂ system were elucidated based on the phase compositions of the NiO–ZnO, ZnO–SiO₂, and NiO–SiO₂ binary systems, reference points, and the unit cell parameters of solid solutions. The NiO–ZnO–SiO₂ ternary system was partitioned by tie-lines into seven simplex fields. Phase equilibria in the NiO–ZnO–SiO₂ system are determined by quasi-binary equilibrium between the end-members of Zn_2–2xNi_2xSiO₄ (x = 0.10) and Ni_2–2yZn_2ySiO₄ (y = 0.25) solid solutions and the tie-lines connecting these end-members with the Ni_0.83Zn_0.17O solid solution, as well as by the tie-line connecting the Ni_1–zZn_zO (z = 0.4) solid solution end-member with Zn₂SiO₄.

A atomic layer deposition (ALD) program for aluminum molybdenum oxide (Al_xMo_yO_z) films based on cyclic reactions of trimethylaluminum (TMA) and molybdenum dichloride dioxide (MoO₂Cl₂) is presented. The effect of adding water vapor to the ALD cycle (TMA–H₂O–MoO₂Cl₂) has been studied. The film growth process was studied in situ using quartz crystal microbalance (QCM). At an ALD temperature of 180°C, linear growth was observed for the TMA–MoO₂Cl₂ and TMA–H₂O–MoO₂Cl₂ processes with a growth rate of 3.79 and 3.94 Å/cycle, respectively. According to X-ray reflectometry and diffraction data, the resulting films had an amorphous structure with a density of ~3.7 g/cm³ and a root-mean-square roughness in the range of 10–12 Å. Both types of films had similar compositions, containing Mo⁺⁶, Mo⁺⁵, and Mo⁺⁴.

A process of SnO nanosheets formation by direct chemical deposition using tin(II) chloride as a tin source and sodium hydroxide as a base has been studied. Crystal structure and microstructure of the obtained powder have been studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM), spectral characteristics have been examined by IR and Raman spectroscopy, while thermal behavior has been analyzed using simultaneous thermal analysis (TGA/DSC) in an air flow. It has been found that the synthesized SnO is resistant to oxidation at temperatures up to 250°C. According to XRD data, the product formed has a tetragonal crystal lattice corresponding to tin monoxide with average coherent scattering region (CSR) size of 21.7 ± 1.3 nm. SEM and AFM analyses revealed that the powder has a hierarchically organized microstructure consisting of nanosheets of 26.2 ± 2 nm thick and lateral dimensions ranging from 0.6 to 4.3 µm. Electronic work function from material surface determined using Kelvin probe force microscopy (KPFM) has been to be of 3.79 ± 0.02 eV.

Argyrodite family compounds and their based phases are of interest as environmentally friendly functional materials. This work presents new phase equilibria data in the Cu₈GeSe₆–Ag₈GeS₆ system obtained by differential thermal analysis (DTA) and X-ray powder diffraction (XRD). The system was found to be not quasi-binary due to the incongruent melting of Cu₈GeSe₆, yet it maintains thermodynamic stability at below the solidus temperature. A continuous solid solution series (δ phase) between the high-temperature phases with both cationic and anionic substitutions was identified. The low-temperature phases were shown to have limited homogeneity regions. Solid solution formation lowers the polymorphic transitions temperatures and extends the homogeneity range of the ion-conducting cubic δ phase down to room temperature and below. At room temperature, the homogeneity range of the δ phase spans 10–70 mol % Ag₈GeS₆. The δ phase in the range 36–64 mol % Ag₈GeS₆ can be classified as a high-entropy alloy (HEA), which offers additional facilities for tailoring its properties through entropy-driven structural stabilization.

Interaction of β-sialons Si₅AlON₇ and Si₄Al₂O₂N₆ with a boron oxide was studied. Boron oxide was introduced in the form of boric acid, the acid content was set up at 0.5 and 5.0 wt %. Samples were sintered at 1650°C in the stream of N₂ for 2 h. It was found that all the samples showed higher densities against those for samples sintered with no aids, however, the densities were still lower as compared to theoretical levels. In most cases disproportionation of the basic phase into phases enriched with aluminum (Si₃Al₆O₁₂N₂) and silicon (Si₂N₂O) occurred. Moreover, when Si₄Al₂O₂N₆ was sintered with an addition of 0.5 wt % of boric acid, a noticeable amount of SiO₂ was also formed. Sintering of Si₅AlON₇ with an addition of boric acid did not lead to sufficient changes in microhardness and bending strength. In contrast, sintering of Si₄Al₂O₂N₆ sintered with an addition of 0.5 wt % of boric acid resulted in an increase in bending strength by ~14%, however, an addition of 5.0 wt % of boric acid caused a decrease in hardness by ~9% and a drop in bending strength by ~36%.

New double complex salts [Ir(NH₃)₆]₄[Fe(CN)₆]₃·12H₂O and [Rh(NH₃)₆]₄[Fe(CN)₆]₃·12H₂O were synthesized and structurally characterized for the first time. The thermal behavior of the synthesized salts in reducing (He/H₂), inert (He), and oxidizing (Ar/O₂) atmospheres was studied in detail. The final product of the decomposition of double complex salts [Ir(NH₃)₆]₄[Fe(CN)₆]₃·12H₂O in reducing and inert atmospheres is a mixture of face-centered cubic and hexagonal close-packed nanosized solid solutions of Ir-Fe and amorphous carbon. The decomposition of [Rh(NH₃)₆]₄[Fe(CN)₆]₃·12H₂O in the same atmospheres leads to the formation of a mixture of ordered and disordered Rh-Fe nanoalloys containing amorphous carbon. In an oxidizing atmosphere, a mixture of metal oxides and metallic iridium (or rhodium) is formed. Based on the data obtained, thermal decomposition of [Ir(NH₃)₆]₄[Fe(CN)₆]₃·12H₂O and [Rh(NH₃)₆]₄[Fe(CN)₆]₃·12H₂O can be considered as a method for producing nanoalloys or oxide systems based on iron and iridium (rhodium).

Layered double hydroxides (LDHs) have proved to be highly effective sorbents for heavy metals and radionuclides. In particular, modification of LDHs with ferrocyanide ions was proposed for the extraction of cesium-137. However, sorption-selective characteristics of modified LDHs in the extraction of cesium radionuclides from model and real solutions of liquid radioactive waste (LRW) still remain unexplored. In this study, Zn-Al-LDH was obtained by direct co-precipitation with subsequent in situ intercalation of ferrocyanide anions into the interlayer space to achieve selectivity to cesium. The adsorption kinetics was studied and the relevant adsorption isotherms were derived; the theoretical maximum sorption capacity was found to be 201 mg/g, while the experimentally obtained value was 197 mg/g. The effect of interfering ions on the adsorption of ¹³⁷Cs was studied and the partition coefficients K_d(¹³⁷Cs) were determined to be 4838 and 1763 mL/g for model solutions of low and moderate salinity, respectively, and 3259 mL/g for seawater. The resulting composite material demonstrated high potential for the selective extraction of cesium radionuclides from aqueous solutions of varying salinity.

The heat capacity of magnetoplumbite-type PrZnAl₁₁O₁₉ was measured by relaxation, adiabatic, and differential scanning calorimetry techniques in the temperature range 2–1848 K. The smoothed heat capacity values were used to calculate the temperature-dependent entropy, enthalpy change, and reduced Gibbs free energy. The enthalpy of solution in lead borate melt at 1073 K was measured by drop-solution calorimetry, and the enthalpy of formation from binary oxides and standard enthalpy of formation at 298 K were estimated. To determine the probability of PrZnAl₁₁O₁₉ decomposition to binary oxides, the temperature-dependent Gibbs free energy of the solid-phase reaction in the temperature range 298–1800 K was estimated.

Subsolidus phase equilibria of the Y₂O₃–Fe₂O₃–Ta₂O₅ system were studied. The compound YFeTa₂O₈ was discovered to exist within a narrow temperature range of 1000–1400°C. Another previously unknown compound, Y₂FeTa₃O₁₂, appeared to exist in the range up to 1000°C, then it decomposed to YTaO₄ and YFeTa₂O₈. The Y₂FeTa₃O₁₂ has a pyrochlore-type structure (space group Fd(bar {3})m) with the unit cell parameter a = 10.3158(6) Å. The existence of the Y_{2 – x}Fe_{1 + x}TaO₇ solid solution in the range x = 0–0.2 was confirmed. The 900 and 1200°C isotherms of the system were designed. The magnetic properties of the YFeTa₂O₈ and Y₂FeTa₃O₁₂ phases in fields up to 5000 Oe in the temperature range 2–300 K were studied; their behavior was typical of paramagnets almost over the entire range of temperatures studied. The effects observed at extremely low temperatures indicate the presence of antiferromagnetic interactions, but they are very weak against the background of the paramagnetic matrix.