Russian Journal of Inorganic Chemistry最新文献

The study deals with the development of a layered biocomposite as a functionally-gradient material (FGM) combining Ti–6Al–4V alloy and bioceramics based on titanium dioxide in the composition with hydroxyapatite, which is promising for the use in metal–ceramic bone implants. A method for FGM formation to overcome confinements of its components such as low mechanical strength of bioceramics and the lack of osteoinduction for titanium medical alloys has been disclosed. Spark and plasma sintering have been used to achieve strong and unsplit joint between ceramics layers and alloy. The study has shown that phase composition of both materials remains stable during their heating, while intermediate layer of β-Ti forms on the contact boundary, which increases mechanical strength of the joint. Microhardness testing has confirmed the integrity of composite with retention of strength at ceramics–alloy interface. The lack of defects and internal stress at the boundary of formed junction indicates its high mechanical stability and shows potentiality of method for possible practical application to design contemporary structurally strong implants with improved osteointegration function.

A new efficient method for the synthesis of solid electrolyte with high lithium-ion conductivity with NASICON structure of composition Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) has been proposed. The advantage of the developed method is the use of liquid-phase precursor based on titanium oxalate complex. A single-phase well-crystallized LATP has found to form at 750°C. The total ionic conductivity value of LATP after sintering at 900°C measured by impedance spectroscopy has been found to be of 2.6 × 10^–4 S/cm at ambient temperature, while activation energy of conductivity has been found to be of 0.28 eV. The proposed method of synthesis is promising for scale-up and mass production.

The precipitation process of bismuth(III) from perchloric acid solutions upon the addition of malonic acid has been studied as a function of the molar ratio of malonate ions to bismuth in the system. A basic bismuth malonate with the composition BiOH(C₃H₂O₄) (compound I) was synthesized, along with two structurally distinct but compositionally identical bismuth malonates containing a water molecule: Bi(C₃H₂O₄)(C₃H₃O₄)H₂O (II) and [Bi(C₃H₂O₄)(C₃H₃O₄)]⋅H₂O (III). Compound I was obtained in an X‑ray amorphous form, whereas the crystal structures of compounds II and III were determined by X-ray diffraction. In compound II, the water molecule coordinates directly to the bismuth atom as a ligand, whereas in compound III this is not observed. Both compounds form one-dimensional (1D) coordination polymers. Upon calcination of compounds II and III at 120°C, anhydrous bismuth malonate with the composition Bi(C₃H₂O₄)(C₃H₃O₄) (IV) is produced via dehydration. All new compounds (I–IV) were characterized by IR spectroscopy, thermal analysis, and powder X-ray diffraction, and their compositions were confirmed by elemental analysis. The structural features of polymers II and III are discussed, including a topological analysis of the electron density in Bi–O contacts, allowing for the identification of primary and secondary bonds within the coordination polyhedra.

Magnetic Fe₃O₄ nanoparticles (NPs) were synthesized by alkaline precipitation from aqueous solutions of divalent and trivalent iron salts. Synthesis of Fe_3-xGd_xO₄ NPs (x = 0.05; 0.1) was performed by adding a calculated amount of Gd(NO₃)₃·6H₂O to the initial solution of iron salt mixture. The phase composition and magnetic properties of the synthesized powders were investigated by X-ray diffraction analysis, ⁵⁷Fe Mössbauer spectroscopy and vibration sample magnetometry at temperatures T = 7, 20 and 300 K. The investigations confirmed the formation of NPs of non-stochiometric Fe_3-δO₄ magnetite, as well as magnetite doped with Gd³⁺ ions. The correlation between the average diameter of NPs of the initial Fe_3-δO₄ powder and doped Fe_3-xGd_xO₄ powder and the salt used in the synthesis, as well as the concentration of Gd (x), respectively, was revealed.

Reaction of solutions containing [Co(NH₃)₆]³⁺ cations and [MHal₄]^2– anions (M = Pt(II), Pd(II); Hal = Cl^–, Br^–) led to the isolation of crystalline powders of double complex salts with varying compositions. In the system with chloride anions, complexes were formed with metal molar ratios depending on the nature of the platinum metal (Co : Pt = 2 : 3, Co : Pd = 1 : 1). It was found that replacing chloride ions in the Co–Pd system with bromide ions leads to the formation of a complex with a Co : Pd ratio of 2 : 3. In the presence of sulfuric acid, compound {[Co(NH₃)₆](SO₄)₂[Co(NH₃)₆]}[PdBr₄] was formed. This compound is reported for the first time and characterized by elemental analysis, X-ray powder diffraction, IR spectroscopy, and single-crystal X-ray diffraction (CCDC no. 2355175). The structures were studied using DFT/PBE0 calculations with the def2tzvp basis set. Topological analysis of the electron density was performed, and molecular graphs of the compounds were constructed, revealing indicators of non-covalent interactions. Their energies and the total effect, which could have a significant electrostatic and inductive influence on the formation of crystal structures, were approximately estimated.

The interaction in the Li–Ir system using Li₃N as a lithium source was studied depending on the temperature, heat treatment time, and total pressure in the system. Using X-ray powder diffraction, it was shown that heat treatment of a powder mixture of Li₃N and Ir in a graphite or BN crucible in the temperature range of 800–1200°C leads to the formation of a substitution solid solution of Ir(Li), with the lithium content decreasing with increasing temperature, heat treatment time and decreasing total pressure in the system. The maximum lithium content in iridium reached 6.2 at %. It was shown that the use of a closed BN container increases the yield of the Ir(Li) solid solution. The use of graphite or BN crucibles prevents the formation of intermetallic compounds of the Li–Ir system.

Au/Bi₂WO₆ nanocomposites as visible-light-driven photocatalyst were synthesized by a sonochemical-assisted deposition method and used for rhodamine B (RhB) degradation under visible light irradiation. Phase, morphology, surface area, atomic vibration, oxidation state of elements and optical properties of as-prepared Bi₂WO₆ and Au/Bi₂WO₆ were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectrophotometry, nitrogen adsorption–desorption isotherm, UV-Visible diffuse reflectance spectroscopy, Brunauer–Emmett–Teller surface area analysis and X-ray photoelectron spectroscopy. The results identified that metallic Au nanoparticles were supported on the surface of thin Bi₂WO₆ nanoplates to create heterostructure Au/Bi₂WO₆ nanocomposites. The Au/Bi₂WO₆ nanocomposites show strong absorption range of visible light in 450–700 nm. The heterostructure 5% Au/Bi₂WO₆ nanocomposites exhibited the photodegradation for RhB with excellent efficiency of 97.91% under visible light irradiation for 150 min due to the Schottky interface of Au nanoparticles and Bi₂WO₆ nanoplates and surface plasmon resonance (SPR) effect of metallic Au nanoparticles. The role of active species in degrading RhB over 5% Au/Bi₂WO₆ nanocomposites was investigated and a photocatalytic mechanism was proposed and explained according to the experimental results.

Physical properties of the chalcogenide material play a major role in specifying their possible applications. In the current work, multicomponent Al(SbTe₂)_1–xSe_x (x = 0.1, 0.2, 0.3, 0.4) chalcogenide glasses have been prepared through melt-quench technique, and physical properties were also investigated. Structural and morphological features have been studied employing X-ray powder diffraction and SEM-EDX techniques. Average coordination number and constraints, as calculated, reveal that the material is an optimum glassy system. Furthermore, the occurrence of lone pair in the composition is assessed. Further investigations regarding the glass transition temperature, the prepared material is examined with the help of Tichy-Ticha and Lankhorst methods.

The solubility regions of ({text{A}}{{{text{g}}}_{8}}{text{G}}{{{text{e}}}_{{1 - x}}}{text{M}}{{{text{n}}}_{x}}{text{T}}{{{text{e}}}_{6}}) solid solutions were determined by structural analysis. The nature of sample conductivity was revealed by studying kinetic parameters in the range of 100–600 K. The samples are p-type and have high resistance below the temperature range of 180–220 K. The electrical conductivity in the range of 220–300 K increases according to the Mott rule, and at T > 320 K a semiconductor behavior is observed in samples of all compositions. In the temperature range of 80–750 K, the features of the field dependences of the specific magnetization σ_m = f(B), as well as the susceptibility of the ({text{A}}{{{text{g}}}_{8}}{text{G}}{{{text{e}}}_{{1 - x}}}{text{M}}{{{text{n}}}_{x}}{text{T}}{{{text{e}}}_{6}}) composition, were studied. The temperature of the magnetic phase transformation “magnetic order–magnetic disorder” of the composition ({text{A}}{{{text{g}}}_{8}}{text{G}}{{{text{e}}}_{{1 - x}}}{text{M}}{{{text{n}}}_{x}}{text{T}}{{{text{e}}}_{6}}) was determined.