Effect of Lithium Sulfide on Electrical Properties of Li2S-LiPO3 Glasses

The temperature and concentration dependences of the electrical conductivity was studied in Li₂S-LiPO₃ glasses. The effect of lithium sulfide additions (22.5-25 mol %) to LiPO₃ on the electrical conductivity was studied. The nature of the conductivity was studied over the whole range of Li₂S concentrations using Tubandt's procedure, and the contribution of electronic component to the total electrical conductivity was examined by Liang-Wagner's polarization method.     

Partitioning of the quinary reciprocal system Li,K‖F,Cl,Br,MoO4 into simplexes and the investigation of its partitioning and stable elements

The quinary reciprocal system Li,K‖F,Cl,Br,MoO₄ was partitioned into simplexes using graph theory. A tree of phases of the system was constructed, and stable elements were identified. The chemical interaction in the system Li,K‖F,Cl,Br,MoO₄ was described by the ion balance method. The stable tetrahedra LiF-KCl-KBr-K₂MoO₄, LiF-KCl-KBr-LiKMoO₄, and LiF-Li₂MoO₄-KCl-KBr and the united stable pentatope LiF-KF-KCl-KBr-K₂MoO₄ were studied by differential thermal analysis, and phase states in the studied simplexes were determined. The compositions of crystallizing phases in the bulk of the studied tetrahedra and pentatope were confirmed by X-ray powder diffraction analysis.     

ZnVSb基压敏陶瓷中尖晶石相形成机理的研究

ZnO压敏电阻陶瓷是一种典型的“晶界特性”功能陶瓷材料，材料的宏观电学特性与陶瓷的显微组织结构有密切联系。由于ZnSb尖晶石相在使ZnO基压敏电阻陶瓷显微形貌细化和均匀化方面有明显促进作用，自ZnO基压敏电阻发明以来．ZnSb尖晶石在其中的形成机理就成为该陶瓷研究领域的热点。     

Synthesis,region of existence,structural characteristics,and conductivity of BI(CR,FE)VOX solid solutions

The results of our studies of solid solutions of the general composition Bi₄V_{2 − x} Fe _x/2Cr _x/2O_{11 − δ} are presented. The crystal-chemical parameters of different polymorphic modifications of BIMEVOX were determined. The particle size distribution was determined by laser diffraction and optical microscopy. The surface of sintered preforms was studied by scanning electron microscopy. The conductivity of sintered poly-crystalline samples as a function of temperature and composition was studied by impedance spectroscopy. The conductivity was depends on the procedure for the synthesis of solid solutions. The most promising compositions were revealed.     

Structural and theoretical studies of (E,E)-benzaldehyde azine and its rhenium(IV) complex

The azine bridged dicatechol ligand (E,E)-benzaldehyde azine (H₄L) was fully characterized by X-ray analysis. The reaction of [ReCl₆]²⁻ with this compound was studied and the novel Re(IV) complex (HNEt₃)(NBu₄)[ReCl₄(H₂L)] was prepared and characterized. The structure and spectroscopy of the compound H₄L and its Re(IV) complex were studied experimentally and by means of density functional calculations.     

Dehydration process of rhodium sulfate crystalline hydrate

The dehydration of the rhodium salt [Rh(H₂O)₆]₂(SO₄)₃·5H₂O was studied by means of thermogravimetry in the temperature range 300–460 K. The kinetics of dehydration (the ligand substitution process) was studied under non-isothermal conditions. A model-free method was used to calculate the activation energy and analyze the process steps; a non-linear regression method was applied to calculate the kinetic parameters of the multistage dehydration reactions. The features of the dehydration kinetics could be explained by the condensation process.     

Hydrolysis of ZrF 6 2− anions in solutions of copper(II) ammine and synthesis of Cu x Zr(OH) y F z nanolayers by the ionic layering method

The possibility to synthesize M_1x M₂(OH) _y F _z nanolayers by the ionic layering method with the use of soluble anionic complexes of metal fluorides was demonstrated. The influence of the concentration and pH of reagent solutions and of the number of ionic layering cycles on the kinetics of layer growth was studied using the example of Cu _x Zr(OH) _y F _z layers. The composition of the synthesized layers was studied by X-ray photoelectron (XPE) spectroscopy, ellipsometry, and electronic and Fourier transform IR (FT-IR) transmission spectroscopy.     

Selective catalytic reduction of nitric oxide with propane over Ni-Al2O3: effect of Ni loading

Summary The SCR of NO by propane in excess oxygen was studied on a Ni-Al₂O₃ catalyst prepared by a coprecipitation method. The effect of Ni loading on the catalytic performance was studied and the optimal Ni loading was found to be 4 % (wt.%). Based on characterization results, highly dispersed nickel species in surface aluminate phase was regarded as the active site for NO reduction by C₃H₈ and NiO phase was the active site for C₃H₈ oxidation by oxygen.     

Effect of bulky substitution on catalytic activity of a manganese salen complex used in biomimetic alkene epoxidation and alkane hydroxylation with sodium periodate

The catalytic activity of Mn(salen)Cl containing tert-pentyl groups at the 3,5-positions of the salen ligand in the epoxidation of alkenes and hydroxylation of alkanes was studied at room temperature, using sodium periodate as an oxygen source. The effects of various axial ligands were investigated in the epoxidation of cyclooctene. Imidazole, as a strong π-donor ligand, was the best axial ligand. The effect of different solvents was studied in the epoxidation of cyclooctene in CH₃CN/H₂O solvent mixture. The epoxidation reactions of cyclooctene by different oxygen donors including NaIO₄, Bu₄NIO₄, KHSO₅, H₂O₂, H₂O₂/urea, NaOCl and tert-BuOOH were also studied and NaIO₄ was selected as oxygen source. The presence of bulky substituents in the 3,5-positions of the salen ligand was found to increase the catalytic activity of this complex.     

Study of the stability of solid polyoxometalate Mo72Fe30 with a buckyball structure

Samples of polyoxometalate Mo₇₂Fe₃₀: [Mo₇₂Fe₃₀O₂₅₂(CH₃COO)₁₂{Mo₂O₇(H₂O)}₂ {H₂Mo₂O₈(H₂O)}(H₂O)₉₁] · ??150H₂O with a buckyball structure, which can be both crystalline and amorphous, were synthesized. It was shown that such samples can be studied by neutron diffraction. The stability of Mo₇₂Fe₃₀ to heating and UV light exposure (in poly(vinyl alcohol) and polyvinylpyrrolidone films) was studied by IR, EPR, and electronic absorption spectroscopy; thermal analysis; and mass spectrometry. Mo₇₂Fe₃₀ was found to be less stable to heating and irradiation in a poly(vinyl alcohol) film as compared with the related polyoxometallate Mo₁₃₂ free of iron. The sorption properties of Mo₇₂Fe₃₀ to organic vapors and its stability under sorption conditions were studied. It was demonstrated that, in addition to sorption, organic substances cause the destruction of buckyballs.     

Bioconversion of isoeugenol into vanillin by crude enzyme extracted from soybean

Crude enzyme extracted from soybean was used to convert isoeugenol into vanillin. The effects of several factors on the bioconversion were studied. Conversion was affected by the armount of substrate and was also improved by the addition of absorbents, among which powdered activated carbon was the best. The effect of H₂O₂ concentration on the conversion was also studied. The optimum concentration of H₂O₂ was 1% (v/v). With 10 g/L of powdered activated carbon and 0.1% H₂O₂ added, vanillin reached a maximum concentration of 2.46 g/L after 36 h, corresponding to a molar yield of 13.3%.     

Liquid Phase Friedel‐Crafts Alkylation over Mixed Metal Oxide Catalyst

Liquid phase Friedel‐Crafts alkylation of benzene with benzyl chloride was carried out over various ferrites viz. CuFe₂O₄, NiFe₂O₄, CoFe₂O₄, ZnFe₂O₄, and MgFe₂O₄. Among the various ferrites ZnFe₂O₄ showed the highest activity. These ferrites were prepared by co‐precipitation technique. The effect of variation of catalyst, speed of agitation and reaction temperature has been studied. Benzylation of other substrates such as toluene, anisole and chlorobenzene was also studied. The catalyst ZnFe₂O₄ was found to be reusable. The acid base properties of the catalyst were studied by cyclohexanol dehydration reaction and the data was correlated with activity.     

Solubility Polytherm of the Ternary System Hexamethylenetetramine-Ammonium Dihydrogen Phosphate-Water

The solubility polytherm of the ternary system hexamethylenetetramineammonium dihydrogen phosphate-water was studied in a wide temperature range. The concentration and temperature ranges of crystallization of the starting components and a new compound, NH₄H₂PO₄·2(CH₂)₆N₄·8H₂O, were determined. The properties and structure of the new compound were studied by X-ray phase, thermal, and IR spectroscopic analyses.     

Differentiation of the Li,Na,K‖NO2,NO3 quaternary reciprocal system and phase formation in its stable partitioning tetrahedron LiNO2-NaNO2-KNO2-KNO3

The Li,Na,K‖NO₂,NO₃ quaternary reciprocal system was differentiated by partitioning the n-dimensional composition diagrams of systems with complexation using incidence matrices and graphs. The constructed tree of phases was confirmed by X-ray powder diffraction analysis. The quaternary system LiNO₂-NaNO₂-KNO₂-KNO₃, which is a stable partitioning tetrahedron of the quaternary reciprocal system Li,Na,K‖NO₂,NO₃, was studied for the first time by differential thermal and visual polythermal analyses and the projection-thermographic method. The phase state diagram of the studied system was constructed using experimental data.     

Synthesis, vaporization, and thermodynamics of ultrafine Nd2Hf2O7 powders

Ultrafine Nd₂Hf₂O₇ powders with the pyrochlore structure are prepared by self-propagating hightemperature synthesis (in the Pechini version). The elemental and phase composition of the powder are studied. Microstructure is studied by scanning electron microscopy. BET specific surface areas are determined. Thermal behavior is studied by TGA/DSC/DTA up to 1473 K. The sintering kinetics of as-synthesized Nd₂Hf₂O₇ powder at various temperatures is studied. Nd₂Hf₂O₇ vaporization in the range 2400–2600 K is studied by Knudsen effusion/mass spectrometry, and the thermodynamic characteristics of this compound are determined.     

Studies in the formation of poly(oxazolidone)s. III. Catalysis and kinetics of the model oxazolidone formation from cyclohexyl isocyanate and phenylglycidyl ether

The reaction of cyclohexyl isocyanate with phenylglycidyl ether was selected as model reaction for the synthesis of cycloaliphatic isocyanate-based poly(2-oxazolidone)s. The selectivity of AlCl₃ and AlCl₃-triphenylphosphine oxide (AlCl₃–TPPO) and AlCl₃-hexamethylphosphoric triamide (AlCl₃–HMPA) complexes was studied for 2-oxazolidone formation. The reaction products were identified by means of the melting point, ¹H-NMR, and IR spectroscopy. The kinetics of the model reaction was studied using AlCl₃-TPPO in o-dichlorobenzene at 120 and 140°C.     

Electrolytic properties and stability of solid solutions of ytterbium sulfide in calcium thioytterbate

Solid solutions of Yb₂S₃ based on CaYb₂S₄ (Yb₃S₄) were prepared by the ceramic and sol-gel methods. The samples were identified by XRD. The electric conductivity of complex sulfide phases with different backgrounds was studied. The length of phases based on CaYb₂S₄ was determined. The thermal stability of the samples was tested and the range of working temperatures was determined.     

Calorimetric studies of β-Ca2SiO4 hydration in solutions of electrolytes

The hydration of β-Ca₂SiO₄ stabilized by thermal treatment and barium addition was studied in CaCl₂, Ca(NO₃)₂ and BaCl₂ solutions. The heat evolution kinetics was followed by calorimetry. A considerable acceleration of the hydration process was found in the presence of electrolytes. The positive influence of barium ions was confirmed. The highest total heat output during the 3-day hydration was found for samples doped with 3 mole % BaO.     

Crystal and molecular structure of diphenyliodonium triiodide

A new salt diphenyliodonium triiodide (C₁₂H₁₀I₄) was obtained. The [C₁₂H₁₀I⁺][I₃⁻] compound was isolated as red brown crystals and studied by single-crystal X-ray diffraction. The structure of diphenyliodonium triiodide consists of separate, virtually linear I₃⁻ anions and C₁₂H₁₀I⁺ cations. Strong intermolecular anion-anion (I₃⁻…I₃⁻) and anion-cation (I₃⁻…I⁺) interactions in the crystal structure leads to a change in the symmetry of triiodide ions. The complex formation in the system organic cation iodide-elementary iodine was studied by spectrophotometry. The complex composition was found (1: 1), and the stability constant of the complex in chloroform was determined (loggB = 3.91).     

Synthesis and physicochemical study of tetraaquatritetraphthalatodiiron(III)

An iron(III) complex of terephthalic acid of the general formula Fe₂[C₆H₄(COO)₂]₃(H₂O)₄.was synthesized. The composition and structure of the complex were studied by X-ray phase analysis and IR spectroscopy. The thermal stability of the complex was studied in the range 20–900°C. It was shown that doping with a Fe₂[C₆H₄(COO)₂]₃(H₂O)₄ reagent improves the rheological properties of heavy oil.