Vol 61, No 3 (2016)

The effect of small amounts of iron(III) ions on the morphology, phase composition, and structure of the products of the hydroxyapatite (HAP) synthesis has been studied by electron microscopy, X-ray powder diffraction, and Mossbauer spectroscopy methods. It has been demonstrated that the introduction of dopant iron(III) ions into the reaction mixture at different stages of HAP formation makes it possible to control crystal growth, morphology, and phase composition. The iron ions are not incorporated into the HAP crystal structure; rather, they form their proper nanophase, as well as adsorption clusters on the HAP surface.

The effects of the base composition and dopants on the saturation magnetization and coercivity of hexaferrites BaAl_xFe_12–xO₁₉, SrAl_xFe_12–xO₁₉, BaGa_xFe_12–xO₁₉, SrGa_xFe_12–xO₁₉, BaSc_xFe_12–xO₁₉ and SrSc_xFe_12–xO₁₉ have been studied. Isomorphic substitutions of Al₂O₃, Ga₂O₃, and Sc₂O₃ for Fe₂O₃ in barium and strontium ferrites are found to increase coercivity due to increasing crystallographic anisotropy constant and to reduce the saturation magnetization value. Processes controlling microstructure formation, specifically recrystallization processes, are shown to have a noticeable effect on the level of properties of the ferrites under study with the use of dopants. The most efficient dopants are boron, calcium, and silicon oxides, which provide the formation of relatively fine-grained structures. The increased coercivity upon doping with these dopants is also due to the formation of grain-boundary interlayers of a nonmagnetic glassy phase and the associated efficient retardation of moving domain walls.

Complex salts [Rh(H₂O)₆]PO₄ (I) and [Rh(H₂O)₆]PO₄ · H₂O (II) were obtained. Dehydration processes of compounds I and II were studied by thermogravimetry and differential scanning calorimetry. The heat effect for the loss of 0.82 ± 0.01 H₂O (hydration) molecule was found to be 54 ± 1 kJ/mol, while that for the loss of coordinated H₂O is 47 ± 1 kJ/mol (for I) and 43 ± 1 kJ/mol (for II). The solid phases of dehydration products were studied by X-ray powder diffraction, IR and ³¹P MAS NMR spectroscopy, and they were found to be polymers.

The effect of the nature of azaheterocyclic ligands L (L is 1,2-diaminobenzene, 2,2’-bipyridyl-amine, 2,2’-bipyridyl, or 1,10-phenanthroline) on the composition and structure of nickel(II) coordination compounds with the [B_nH_n]^2– anions (n = 10, 12) has been studied. Conditions to isolate complexes of general formulas [NiL₂(H₂O)₂][B_nH_n] and [NiL₃][B_nH_n] have been found. The structures of [Ni(DAB)₂(H₂O)₂][B₁₀H₁₀] · H₂O, [Ni(BPA)₂(H₂O)₂][B₁₀H₁₀] · 3H₂O, [Ni(Bipy)₃][B₁₀H₁₀], [Ni(Bipy)₃][B₁₀H₁₀] · 3CH₃CN · 0.5H₂O, [Ni(Phen)₃][B₁₀H₁₀] · 4DMF · 0.32H2O[Ni(Phen)3][B12H12] · 1.5DMF · 0.25H₂O, and [Ni(Phen)₃](Et₃NH)[B₁₀H₁₀]_1.5 · 1.75CH₃CN have been determined by X-ray diffraction. Structural features of the complexes including intermolecular contacts of different elements of the structures are discussed.

Triphenylbismuth bis(3,4-dimethylbenzenesulfonate) Ph₃Bi(OSO₂C₆H₃Me_2-3,4)₂ (I) has been synthesized by the reaction between triphenylbismuth and 3,4-dimethylbenzenesulfonic acid in the presence of tert-butylhydroperoxide (1: 2: 1 mol) in ether. The bismuth atom in complex I has a trigonal bipyramidal coordination to arenesulfonates substituents in axial positions (axial OBiO angle, 173.99(8)°; equatorial CBiC angles, 106.94(11)°, 112.24(11)°, 140.77(11)°). The Bi‒C distances are 2.189(3), 2.192(3), and 2.197(3) Å; the Bi‒O distances are 2.284(2) and 2.301(2) Å. Some intramolecular contacts are observed between the central atom and the oxygen atoms of sulfonate groups at the maximum equatorial angle (Bi···O 3.122(3), 3.189(4) Å).

Structural characteristics and energies of [UO₂Cl₄(BMIm)_n]^(n–2)+ (n = 1-4) solvation complexes have been studied by the density functional theory (DFT) method in the SVWN5 local functional approximation.

The topological properties were considered for melting diagrams of ternary reciprocal systems with constant-composition phases or with isomorphic diagrams with limited solid solutions. An algorithm for constructing the diagrams was described, and an example was given for a melting diagram with one binary peritectic compound and two ternary stoichiometric compounds, all melting without decomposition. A problem of enumeration of all the phase diagrams with such a set of compounds was solved.

We present the results of thermodynamic analysis of the behavior of gaseous and gas-forming impurities at different stages of calcium production, including electrolysis of calcium chloride, vacuum distillation of calcium from copper–calcium alloy, mechanical dispersing, and remelting and granulation of distilled calcium from the melt. The mechanisms of transfer of H, C, N, and O impurities at all stages of the processes under study are discussed. It is shown that in order to produce high-purity calcium, deep degassing needs to be performed when heating the materials loaded at the distillation, remelting, and granulation stages under condition that the equipment is highly air-tight. Distillation of calcium is recommended to be carried out at temperatures that exceed the process start temperature by no more than 20 K.

The quinary reciprocal system Li, K || F, Br, MoO₄, WO₄ was partitioned into simplexes using graph theory by writing an adjacency matrix and solving a logical expression. A tree of phases of the system was constructed. The tree of phases has a linear structure and consists of four stable partitioning tetrahedra, two stable pentatopes, and three stable hexatopes. In the quinary reciprocal system Li, K || F, Br, MoO₄, WO₄, crystallizing phases were predicted. The stable tetrahedron LiF–KBr–Li₂MoO₄–Li₂WO₄ of the quinary reciprocal system Li, K || F, Br, MoO₄, WO₄ was studied by differential thermal analysis and X-ray powder diffraction. There are no invariant equilibrium points in the tetrahedron. Continuous series of solid solutions Li₂Mo_xW_1–xO₄ do not decompose.

Heterogeneous equilibria in the manganese perchlorate–urea–perchloric acid–water quaternary system at 25°С were studied by investigating solubility. The crystallization regions were determined for the initial solid components, eutonic compositions of ternary systems constituting the quaternary system, binary compounds of urea with manganese perchlorate and perchloric acid, and also two new coordination compounds containing simultaneously manganese perchlorate, urea, and perchloric acid: Mn(ClO₄)₂ · 4CO(NH₂)₂ · HClO₄ and Mn(ClO₄)₂ · 2CO(NH₂)₂ · HClO₄.

The distribution of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc between aqueous solutions of their salts and solutions of 2-phosphorylphenoxy acid amides in dichloroethane containing an ionic liquid (1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide) have been studied. Metal ion extraction has been found to increase considerably in the presence of this ionic liquid in the organic phase. The stoichiometries of extractable complexes have been determined. The influence of aqueous HNO₃ concentration and of the nature of extractant and ionic liquid on the efficiency of REE(III) and scandium(III) recovery to the organic phase has been considered.

The metal exchange of Cd(II) octaphenyltetraazaporphyrin with CoCl₂ and MnCl₂ was studied by spectrophotometry in DMF and DMSO. The kinetic parameters of the metal exchange were determined. A possible stoichiometric reaction mechanism was proposed.

Conditions of vanadium(V) extraction from sulfuric and hydrochloric acid solutions with kerosene solutions of hydrazides and N’,N’-dimethylhydrazides derived from fractions of Versatic 10 and Versatic 1519 branched higher carboxylic acids were studied. Conditions of vanadium(V) back extraction from organic phase were studied. For diluted acid solutions, ratios were found to be [V(V)]: [reagent] = 1: 1 and 1: 5 for sulfuric acid media and 1: 1 and 1: 8 for hydrochloric acid media.