Russian Journal of Inorganic Chemistry最新文献

The phase formation, morphology, and optical properties of aluminum oxynitride (Al₅O₆N) doped with 0.01–5.0 at % of vanadium ions (relative to aluminum) have been studied. All samples fabricated by calcining mixtures of Al₂O₃, AlN, and V₂O₅ at 1750°C in a nitrogen flow are practically single-phase γ-AlON with minor impurities of aluminum nitride, as well as VC, VN, VO, or their solid solutions at a vanadium content of ≥0.1 at %. In AlON:V, the band gap E_g = 5.82–5.94 eV varies depending on the vanadium concentration. The luminescence of AlON:V is due to intrinsic defects and impurity luminescence centers. The presence of vanadium in AlON leads to an increase in the optical absorption and a decrease in the intensity of intrinsic luminescence because of the formation of vanadium-containing impurity phases.

New stybonium complexes containing polyanions have been obtained. Alkylation of tris(2,6-dimethoxyphenyl)stibine with ethyl iodoacetic acid synthesized [Ar₃SbCH₂C(O)OEt]I₃, Ar = 2,6-(MeO)₂C₆H₃, which is also the product of the reaction of [Ar₃SbCH₂C(O)OEt]I and I₂. The reaction of [Ar₃SbEt]I with mercury diiodide leads to {[Ar₃SbEt][Hg₃I₇]}_n, where Ar = 2,6-(MeO)₂C₆H₃. Compounds [Ar₃SbCH₂C(O)OEt]I₃ and {[Ar₃SbEt][Hg₃I₇]}_n were characterized by X-ray diffraction. Antimony and mercury atoms were found to have a distorted tetrahedral coordination. Bond angles are in the ranges: ∠CSbC 104.2(2)°‒113.9(1)° and ∠CSbC 102.4(4)°‒116.0(5)°, ∠IHgI 97.06(2)°–121.28(2)°.

Polyferrophenylsiloxanes based on iron(III) chelate and polyphenylsiloxane with different siloxane-to-sodium hydroxide ratios have been synthesized under mechanochemical activation conditions. It has been shown that the polymer yield after precipitation with petroleum ether is 37–52%. The polyferrophenylsiloxane composition closest to the specified one has been obtained at the ratio Si : Na = 1. The resulting composites have been studied using IR spectroscopy, X-ray diffraction, gel chromatography, and thermogravimetry. An XRD study has shown the introduction of iron atoms into the siloxane structure. The presence of sodium ions during the reaction in subsequent syntheses has made it possible to bind the released acetylacetone and fabricate polyferrophenylsiloxane with a specified Si : Fe ratio. However, with a further increase in the hydroxide content, the Si : Fe ratio is violated. A study of the magnetic properties of polyferrophenylsiloxanes has shown that they are superparamagnets. After heating them to 600°C, magnetization increases sharply (magnetic saturation) and hysteresis is observed.

Natural and synthetic aluminosilicates currently have a wide application range. Silicon-containing wastes of rice production are of great interest as a source of raw materials for aluminosilicate production. The purpose of this work was the template synthesis of micro- and mesoporous materials from rice husk using PEG-6000. The prepared samples were characterized by differential thermal analysis (DTA) and IR spectroscopy, which showed the incorporation of PEG into the potassium aluminosilicate structure during the sol–gel process. The specific surface areas S_sp of the prepared samples and their pore-size distributions were determined by low-temperature nitrogen adsorption, which showed that the pore radius increased from 100 to 200 Å when the PEG concentration in sol–gel synthesis changed from 5 to 20 mmol/L. Scanning electron microscopy (SEM) showed that the template changed the surface morphology of the samples and promoted their structuring.

At present time, there is fast growth in the use of polymer composite materials in all areas of industry due to their unique properties: high strength, low density, and corrosion resistance. Because of development of new technologies, there is necessity to design a new class of environmentally benign materials that provide efficient and economic employment of raw materials. In this work, synthetic nanostructured aluminosilicates with prescribed Si/Al ratio equal to 1, 3, and 5 have been considered as polytetrafluoroethylene modifiers. Phase elemental composition and thermal behavior of the prepared compounds has been studied. The use of aluminosilicates has been found to favor to increase in tensile strength by 40% and relative elongation at rupture by 70% relative to the initial polymer matrix. The introduction of aluminosilicate is accompanied by increase in wear resistance by 521 times. Thus, we have prepared a new class of modifiers for polymer composite materials.

Chromato-mass spectrometry has been used to study the reactions of coordinated ligands in chromium and boron difluoride acetylacetonate complexes. It has been established that bromine- and thiophenyl-substituted acetylacetonates of boron difluoride, unlike chromium complexes, do not react with thiophenol. The reaction of thio-substituted chelates with SO₂Cl₂ also proceeds differently. In chromium complexes, the reaction involves the substitution of the thioalkyl or thioaryl group with a chlorine atom. Thioethyl-substituted boron difluoride acetylacetonate reacts with SO₂Cl₂ similarly to aromatic analogs, leading to chlorination of the ethyl group. However, thioaryl-substituted boron difluoride acetylacetonate does not react with SO₂Cl₂. Additionally, it was found that bromine- and thio-substituted chromium acetylacetonates react with sulfenyl chlorides, replacing the α-substituent with a chlorine atom. It is suggested that the difference in the reactivity of chromium and boron difluoride acetylacetonates is due to the different charge distribution in the chelate cycle. The strong electron-accepting nature of the BF₂ group leads to a positive charge on the substituent attached to the chelate ring in boron complexes.

A new procedure for deposition of VO₂ films on single-crystal sapphire supports from alcoholic solutions under hydrothermal conditions has been proposed. The obtained materials show sharp dielectric–metal transition with change in electrical resistance value up to four orders of magnitude in proximity to critical temperature (68°C). Conditions for the synthesis of films comparable in electrophysical characteristics with analogs prepared in aqueous media have been found. The suggested procedure opens new possibilities for the hydrothermal synthesis of film oxide materials.

The aim of this work was to investigate the effect of organic and inorganic modifying agents on the internal structure and surface properties of vermiculite from the Kovdor deposit in an alkaline medium. Vermiculite from the Kovdor deposit was treated with various compounds in an alkaline medium (sodium hydroxide, sodium stearate) with successive addition of copper chloride and potassium hexacyanoferrate(II) solutions. According to powder X-ray diffraction data, the introduction of stearate ion leads to an increase in the interplanar spacing compared to pristine vermiculite. The increase in the coherent scattering region attests to an increase in the degree of crystallinity and considerable interaction of the modifying agent with the surface. The subsequent addition of potassium hexacyanoferrate(II) leads to further increase in the interplanar spacing because of the bulky hexacyanoferrate ion; however sharp decrease in the coherent scattering region indicates exfoliation of the layered silicate, which leads to a decrease in the surface area due to increasing content of amorphous structure.

Cathode materials based on Li₂CoMn₃O₈ solid solutions have been synthesized by a combined method and their characteristics have been studied. It has been found that Li₂CoMn₃O₈ has high electrochemical properties, which makes it a promising cathode material for lithium-ion batteries, an alternative to LiCoO₂. Using X-ray diffraction analysis and spectrometry, the resulting phases have been identified, and their chemical composition has been determined. The structure and morphology have been studied by electron microscopy and Brunauer–Emmett–Teller methods. A technological scheme for fabricating Li₂CoMn₃O₈ has been proposed, which ensures the formation of nanosized samples with a high specific surface area and improved electrochemical characteristics. The electrochemical properties of the synthesized samples are discussed.

This paper presents the synthesis of layered complex carbide of the composition (Cr,V)C using reactive spark plasma sintering (SPS-RS) and hydrothermal acid etching. Using SEM and TEM, the macrostructure and nanostructure at each stage of MAXene synthesis was studied in detail. The presence of characteristic features of the formation of two-dimensional carbide in the form of particles and fragments of a multilayer structure at the macro- and nanolevel was confirmed. Using EDS and powder X-ray diffraction, the elemental and phase composition of the samples was studied. As a result, it was found that the expected MAX-phase Cr₂VAlC₂ in the composition of the sample obtained by SPS is absent. At the same time, a phase of mixed bimetallic carbide (Cr,V)C was detected at all stages of synthesis, for which the crystal lattice parameters, including the unit cell volume, change significantly after acid etching. Obvious changes in the bulk and crystalline structure of (Cr,V)C correspond to the formation of two-dimensional nanoparticles in the synthesized material. The magnetic characteristics study showed that all samples have magnetic hysteresis with relatively low values of coercivity and remanence to saturation magnetization ratio. Low-temperature measurements showed a slight increase in magnetic moment with decreasing temperature for the sample obtained under reaction SPS conditions before acid etching in HF, without significant changes in magnetic behavior of the samples.