Russian Journal of Inorganic Chemistry最新文献

A vanadium pentoxide film was obtained via dip-coating using vanadyl alkoxoacetylacetonate as a precursor. The material crystallizes in the tetragonal β-V₂O₅ modification and exhibits pronounced (200) texturing. It consists of one-dimensional structures with an aspect ratio of at least 10, some of which are consolidated into agglomerates where the particles are in contact along their long facets. According to Raman spectroscopy and the measured work function (4.63 eV) obtained by Kelvin probe force microscopy (KPFM), the oxide contains a noticeable amount of V⁴⁺ species. In terms of electrochromic behavior, the material exhibits anodic electrochromism, changing color to pale blue upon reduction and to a less transparent yellow-orange upon oxidation. The optical contrast reaches up to 27% in the blue region of the visible spectrum. These findings suggest that β-V₂O₅ materials synthesized using vanadyl alkoxoacetylacetonate are promising candidates for application in electrochromic devices.

The electronic structure and the X-ray photoelectron spectrum of the valence electrons of the LrO₈ cluster—a fragment of the lawrencium dioxide lattice—have been calculated by the relativistic discrete variational method. A scheme of the valence molecular orbitals in the binding energy range 0 to ~50 eV has been built. The outer valence molecular orbitals (OVMO) are made up largely of the Lr6d and 5f and O2p atomic orbitals, and the inner valence molecular orbitals (IVMO) are made up of the Lr6p_3/2 and O2s atomic orbitals. The MO scheme contributes to the understanding of the chemical bond nature and the valence XPS spectrum of the LrO₈ cluster. The relative contribution of the OVMO and IVMO electrons to the covalent component of chemical bond has been evaluated. The valence XPS spectrum of the LrO₈ cluster has been compared to those of AnO₂ of other actinides.

The low temperature hydrothermal synthesis of copper nanowires in the presence of oleylamine and ascorbic acid has been investigated. It was found that ascorbic acid can be effectively used as a “soft” reducing agent in the preparation of one-dimensional copper nanostructures. By varying the synthesis conditions, it is possible to modify their microstructural characteristics, as evidenced by the shift in the characteristic absorption band observed via UV–Vis spectrophotometry. X-ray powder diffraction confirmed the formation of nanowires with the target crystalline structure and an average coherent scattering domain size ranging from 25.7 to 28.8 nm. The microstructural features of the obtained materials were investigated using scanning and transmission electron microscopy, as well as atomic force microscopy. In particular, it was shown that decreasing the synthesis temperature from 110 to 90°C and increasing the oleic acid content in the reaction mixture led to the formation of copper nanowires with an average diameter of approximately 70.2 nm and an aspect ratio of about 285.

Modified silica aerogels have been obtained by co-gelation of tetramethoxysilane and acylated (3-aminopropyl)trimethoxysilane of general formula (MeO)₃Si–(CH₂)₃–NHC(O)–R) followed by supercritical drying in CO₂. Alkyl substituent elongation has been shown to increase aerogel hydrophobicity up to formation of superhydrophobic materials (contact angle is 163.7°). Specific surface area of the aerogels can vary from 40 to 1375 m²/g.

Nanocrystalline powders of copper sulfide with covelline and djurleite structure have been synthesized by chemical deposition from aqueous solutions of copper nitrate and sodium sulfide, as well as aqueous solutions of copper nitrate using thiourea as sulfiding agent in the presence of Trilon B as a stabilizer. Reaction of copper nitrate with sodium sulfide has been found to result in copper sulfide powders with the main phase showing the structure of hexagonal covelline with nanoparticle size of 3–6 nm. Moreover, the reaction produces monoclinic djurleite Cu_2–xS with particle size of ~70 nm and small non-stoichiometry in copper sublattice. Deposition from weakly alkaline aqueous solutions of copper nitrate, thiourea, and Trilon B on heating to ~90–100°C allowed preparation of monophase nanocrystalline CuS powders with particle size of 45–55 nm with structure of hexagonal covelline.

New double cerium(IV)-rubidium phosphates, RbCe₂(PO₄)₃ and Rb₂Ce(PO₄)₂·хH₂O, have been obtained under hydrothermal conditions. Using the crystallographic parameters of isostructural compounds, the unit cell parameters of RbCe₂(PO₄)₃ and Rb₂Ce(PO₄)₂·хH₂O were calculated from X-ray powder diffraction data. The following values were obtained: for RbCe₂(PO₄)₃, a = 17.494(1) Å, b = 6.7759(5) Å, c = 7.9831(5) Å, β = 102.875(4)°, V = 922.51(10), ų, Z = 4 (space group C2/c); for Rb₂Ce(PO₄)₂·хH₂O, a = b = 6.8663(1) Å, c = 17.6562(5) Å, V = 832.42(3) ų, Z = 4 (space group I4₁/amd). Thermal behavior analysis of the synthesized compounds was performed, including phase composition determination of the thermolysis products. The results demonstrate that the initial structures exhibit relative thermal stability, with decomposition onset temperatures of approximately 500°C. At higher temperatures, progressive thermolysis leads to the formation of CePO₄ alongside RbPO₃ or Rb₄P₂O₇, depending on conditions.

Subsolidus phase equilibria in the La₂O₃–Y₂O₃–SrO system at temperatures up to 1350°C were studied. The La_{1 – x}Sr_xYO_{3 – δ} (x = 0–0.26) solid solutions and SrY₂O₄-base solid solutions extending between 0 and 15 mol % La₂O₃, between 28 and 50 mol % Y₂O₃, and between 50 and 70 mol % SrO were found to exist in the system. The phase equilibria in the La₂O₃–Y₂O₃–SrO system are comparable to those known to occur in its boundary binary systems. Vibrational spectra and X-ray luminescence spectra (XLS) of La_{1 – x}Sr_xYO_{3 – δ} solid solutions were recorded. The IR spectra featured the existence of OH^– groups captured by the crystal lattice in La_{1 – x}Sr_xYO_{3 – δ} samples. F centers were shown to be formed in the perovskite structure, and the luminescence spectral characteristics of these centers were considered. The X-ray luminescence intensity of F centers is proposed as a criterion to estimate the extent of capture of OH groups by the perovskite lattice.

The variable-composition compounds Bi(Al_1–xFe_x)₃(PO₄)₂(OH)₆ with an alunite-type structure were obtained by hydrothermal synthesis in the Bi₂O₃–Al₂O₃–Fe₂O₃–P₂O₅–H₂O system. Using experimental data on the miscibility limits of components in (1–x)BiAl₃(PO₄)₂(OH)₆–xBiFe₃(PO₄)₂(OH)₆, parameters of the subregular solution model were determined (Q₁ = 6.395, Q₂ = 8.987 kJ/mol) and the curves for spinodal and binodal decomposition of solid solutions with alunite-type structure were calculated. According to thermodynamic calculations, the compounds BiAl₃(PO₄)₂(OH)₆ and BiFe₃(PO₄)₂(OH)₆ can be formed at temperatures above 122 and 170°C, respectively, which is consistent with the experimental data obtained in the present study, indicating the absence of compounds with alunite-type structure at 160°C in the 0.8 < x ≤ 1 range.

The structure of ZnZrF₆·6H₂O and ZnZrF₆·5H₂O (high- and low-temperature forms) crystal hydrates and products of their thermal destruction ZnZrF₆·4H₂O, ZnZrF₆·2H₂O, ZnZrF₆, and ZnZr₂F₁₀·2H₂O have been studied. With the exception of ZnZr₂F₁₀·2H₂O, compounds of ZnZrF₆·nH₂O (n = 6, 5, 4, 2, 0) are isostructural to their formula analogs NiZrF₆·6H₂O, α- and β-MgZrF₆·5H₂O, CuZrF₆·4H₂O, MgZrF₆·2H₂O, and MgZrF₆, respectively. The structure of ZnZr₂F₁₀·2H₂O is built of unique infinite network anionic layers (_{infty }^{2})[Zr₂F₁₀]^2–, in which ZrF₈ square antiprisms are formed tetranuclear cycles and are shared six of their vertices with four neighboring Zr-polyhedra according to the law “…–edge–edge–vertex–vertex–…”; ZnF₄(H₂O)₂-octahedra link Zr-layers to each other into a framework.

The dependence of the microstructural properties of copper nanowires on temperature (110, 120, and 130°C) and time (4 and 8 h) has been studied for the hydrothermal synthesis of copper nanowires using oleylamine and dextrose. The change in diameter of the Cu nanowires formed was monitored by spectrophotometry in the visible range. X-ray powder diffraction was used to confirm the target crystal structure and the absence of copper oxide impurities, as well as to show the nonlinear dependence of the average size of the coherent scattering region on the temperature and duration of the synthesis process. The scanning electron microscopy results showed that, in general, increasing the temperature and duration of the synthesis process leads to an increase in the length of the formed copper nanowires from 45 to 150 μm, i.e. under certain conditions, ultra-long structures are obtained. As a result, the aspect ratio varies from 782 to 2358 by altering the synthesis conditions. Transmission electron microscopy shows that the sample obtained at 110°C (4 h) differs from the others by the presence of particles up to 10 nm in size on the surface of the nanowires. The microstructural parameters of the obtained materials were also studied by atomic force microscopy, and the values of the electronic work function of the individual copper nanowire surface in ambient atmosphere were determined by Kelvin probe force microscopy.