Vol 62, No 1 (2017)

A study was made into the morphology, composition, and electrochemical and mechanical properties of protective composite coatings on various aluminum alloys, including those doped with Sc, Cu, and Ni. It was established that protective coatings significantly increase the corrosion resistance of the alloys in a 3% NaCl solution. Composite coatings produced by triple dip coating in an superdispersed polytetrafluoroethylene suspension have unique corrosion-resistance properties, reducing the corrosion current density for all the protected alloys to 3.1 × 10^–11–4.0 × 10^–12 A/cm², which is more than three orders of magnitude lower than that for coatings formed by plasma electrolytic oxidation and five orders of magnitude lower than that for alloys without coating.

The results of physicochemical examination (chemical analysis, XRD, IR spectroscopy) of the products synthesized in the Ca(OH)₂–H₃PO₄–H₂O system under microwave exposure are used to analyze the composition–synthesis conditions–structure–dispersion–properties relationships and to determine the effect of microwave irradiation on the size and morphology of the synthesized calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) nanocrystals.

Tantalum nitrides are synthesized by ammonolysis of a mesoporous magnesiothermic tantalum powders. The effect of specific surface area of the powders and synthesis temperature on product composition is shown. Nitrogen content in the ammonolysis product of tantalum powder with a specific surface area of 56 m² g^–1 corresponds to oxynitride TaON exposed to 600°C for 1 h. The specific surface area of the oxynitride is 35 m² g^–1.

Three new uranyl complexes [UO₂(C₅H₆O₄)(Meur)] (I), [UO₂(C₅H₆O₄)(Aa)] (II), and [(UO₂)₂(C₅H₆O₄)₂(Tmur)₂(H₂O)] • H₂O (III), where C₅H₆O₄²⁻ is glutarate anion, Meur is methylcarmamide, Aa is acetamide, and Tmur is tetramethylcarbamide, have been synthesized and characterized by X-ray diffraction. 1D uranyl-glutarate complexes have been found in the structures of all compounds; in I and II their composition is [UO₂(C₅H₆O₄)(L)] and crystallographic formula is AQ²¹M¹ (where A = UO₂²⁺, Q²¹ = C₅H₆O₄^2-, and M¹ = L = Meur or Aa). In crystals III, chain complexes have the composition [(UO₂)₂(C₅H₆O₄)₂(Tmur)₂(H₂O)] and crystallographic formula A₂Q₂⁰²M₃¹ (where A = UO₂²⁺, Q⁰² = C₅H₄O₆^2-, and M¹ = Tmur or H₂O). All compounds were characterized by IR spectroscopy. Structural features of all known complexes of uranyl glutarate with neutral ligands have been discussed.

The title coordination polymers of Zn(II), Cd(II), Pb(II) based on H₂L (H₂L = N-[(3-pyridine)-sulfonyl]aspartate) had been synthesized in the same material ratio, under different synthesis temperature. The results show that the polymer 1 is a three-dimensional structure and synthesized under room temperature condition; the polymers 2–4 are two-dimensional structure and synthesized under hydrothermal synthesis conditions. A structural comparison of these polymers suggests that different reaction temperatures play important role in the construction of resulting architectures for 1–4. Fluorescence properties of these polymers showed blue shift occurred.

Evolution of three-dimensional configurations, electronic properties, and energies of attachment of donor and acceptor ligands to Au₁₂M (M = Hf, Ta, W, Re, and Os) intermetallic clusters were studied by quantum-chemical methods. The attachment of F to clusters Au₁₂Re and Au₁₂Os and the attachment of H to clusters Au₁₂Ta and Au₁₂Hf are found to give rise to more symmetric structures. The energies of attachment of F to >18-electron Au₁₂M clusters and the energies of attachment of H to <18-electron clusters exceed the energies of attachment of the same atoms to 18-electron cluster Au₁₂W and to cluster Au₁₂.

Continuous monazite solid solutions La(VO₄)_1–х(PO₄)_х were prepared by ceramic technology. Heat capacities of three samples (х = 0.25, 0.50, and 0.75) were measured by adiabatic calorimetry at low temperatures (5–350 K). Thermodynamic functions were calculated in the range of temperatures studied.

Electrical resistivity ρ, Hall factor R_H, magnetic resistance (R_m–R₀)/R₀, and magnetic-field-dependent resistances were measured in 70 mol % Cd₃As₂ + 30 mol % MnAs composite at fixed values of high hydrostatic pressures (up to p ≤ 9 GPa). The ρ, R_H, and (R_m–R₀)/R₀ versus pressure curves feature a phase transition at p = 4–4.3 GPa. Field-dependent magnetic resistance features a negative pressure-induced trend.

Manganese-doped solid solutions In_1–xGa_xSb (x = 0.05, 0.1, 0.5, 0.9, 0.95) were synthesized. It was found that, in samples of the compositions In_0.95Ga_0.05Sb〈Mn〉 and In_0.05Ga_0.95Sb〈Mn〉, a homogeneous substitutional solid solution forms, into which manganese-containing clusters are incorporated. The clusters are mainly located at crystal lattice defects—grain boundaries and dislocations. The ferromagnetic properties of the obtained samples at room temperature and higher are caused by clusters Mn_1+xSb, the effective size of which is about 180–300 nm.

The ternary eutectic system CsF–KF–NaF was studied by differential thermal analysis. The melting point and composition of the ternary eutectic were determined, and so was the boundary of the region of limited series of solid solutions within the composition triangle. The compositions of crystallizing phases were confirmed by X-ray powder diffraction analysis. The specific enthalpy of melting of the ternary eutectic was experimentally found.

Acid and coordination properties of 5,10,15,20,21-pentaphenyl-2,3,7,8,12,13,17,18-octaethylporphine in 1,8-diazabicyclo[5.4.0]undec-7-ene–acetonitrile system at 298 K have been studied by spectrophotometric titration. It has been found that titration causes deprotonation of nitrogen atom of the pyrrole ring to produce monodeprotonated form. Acid dissociation constant of the compound in 1,8-diazabicyclo[5.4.0]undec-7-ene–acetonitrile system at 298 K has been determined. Complexation of molecular and deprotonated forms of the ligand with silver nitrate has been studied, kinetic parameters of the corresponding reactions have been obtained. Kinetics of silver complexation with the studied ligand by ionic and molecular mechanism has been analyzed.

Optically transparent polymeric materials PMMA: Cd(Pb)S have been synthesized by polymerization of methyl methacrylate, which concurrently acts as a reaction medium for synthesis of metal sulfides, dispersion medium for the resulting colloidal solution forming during synthesis, and the base of compositions. Dependences of cadmium sulfide luminescence on the concentrations, concentration ratios of the initial compounds, reaction medium composition, and temperature have been established. The observed changes in the spectra are related to the introduction of lead(II) into compositions, complex formation on the surface of colloidal particles, and the effect of polar acetonitrile.