Synthesis,structure, and electric properties of oxygen-deficient perovskites Ba<Subscript>3</Subscript>In<Subscript>2</Subscript>ZrO<Subscript>8</Subscript> and Ba<Subscript>4</Subscript>In<Subscript>2</Subscript>Zr<Subscript>2</Subscript>O<Subscript>11</Subscript>

Perovskite phases Ba₃In₂ZrO₈ and Ba₄In₂Zr₂O₁₁ with the nominal concentration of structural oxygen vacancies 1/9 and 1/12, respectively, were synthesized by solid-phase and solution methods. X-ray diffraction showed cubic symmetry of both phases with the unit cell parameter a = 0.4193(2) and 0.4204(3) nm, respectively. The absence of superstructural lines resulted in the conclusion on statistical arrangement of oxygen vacancies. Thermogravimetry and mass spectrometry proved that both phases can reversibly absorb water from gas phase (pH₂O = 2 × 10⁻² atm) with observed correlation between the concentration of oxygen vacancies and amount of absorbed water. The total water amount was up to 0.9 mol per formula unit or, if recalculated for perovskite unit ABO₃, 0.3 and 0.23 mol H₂O, respectively. The temperature curves of coductivity in the atmosphere with various partial water vapor pressures (pH₂O = 3 × 10⁻⁵ and 2 × 10⁻² atm) showed significantly higher conductivity and lower activation energy (0.52 eV) in humid atmosphere due to proton transfer. The proton conductivity is up to 5 × 10⁻⁴ Ohm⁻¹ cm⁻¹ at 300°C for Ba₃In₂ZrO₈ specimen. IR spectrometry showed that protons in the structure exist primarily in OH-groups.     

NH<Subscript>4</Subscript>V<Subscript>3</Subscript>O<Subscript>7</Subscript>: Synthesis,morphology, and optical properties

The effect of the method used for the synthesis of NH₄V₃O₇ on its morphology, textural parameters, and optical properties was studied. Ammonium vanadate NH₄V₃O₇ was prepared by treating NH₄VO₃ in the presence of citric acid under hydrothermal (4.0 ≤ pH ≤ 5.5, T = 180–200°C, 48 h) and microwave–hydrothermal (3.5 ≤ pH ≤ 5.0, T = 180–220°C, 20 min) conditions. Self-assembled NH₄V₃O₇ microcrystals crystallizing in monoclinic system with unit cell parameters a = 12.247(5) Å, b = 3.4233(1) Å, c = 13.899(4) Å, β = 89.72(3)°, and V = 582.3(4) ų (space group P2₁) were shown to be formed independently of the method used to treat the reaction mixture. The morphology of NH₄V₃O₇ particles was shown to depend on рН of the reaction mass and the method of synthesis. The structural features of NH₄V₃O₇ were studied by IR, UV, and Vis spectroscopy, and the optical bandgap was determined.     

Five-component reciprocal systems Na,K∥Cl,CO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>,WO<Subscript>4</Subscript> and Na,K∥F,CO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>,WO<Subscript>4</Subscript>

Five-component reciprocal systems Na,K∥Cl,CO₃,MoO₄,WO₄ and Na,K∥F,CO₃,MO₄,WO₄ have been studied by differential thermal analysis (DTA) and X-ray powder diffraction (XPD). The systems have been triangulated to phase simplexes. The main reciprocal and complex-formation reactions have been revealed. The stability of [Na,K]₂CO₃, Na₂[Mo,W]O₄, and K₂[Mo,W]O₄ binary solid solutions and the nonexistence of quintuple invariant points in the title systems have been verified.     

Synthesis,crystal structure,and vibrational spectra of M<Subscript>4</Subscript>V<Subscript>2</Subscript>O<Subscript>3</Subscript>(SO<Subscript>4</Subscript>)<Subscript>4</Subscript> (M = K,Rb, Cs)

Synthesis was performed and physicochemical properties were studied for the M₄V₂O₃(SO₄)₄ complexes, where M = K, Rb, or Cs. Their crystal structures were determined using the set of data from X-ray diffraction and neutron diffraction studies. All compounds crystallize in a triclinic lattice (space group \(P\bar 1\), Z = 2) with the parameters: a = 7.7688(2), 7.8487(1), 8.1234(1) Å; b = 10.4918(3), 10.8750(2), 11.1065(1) Å; c = 11.9783(4), 12.1336(2), and 11.8039(1) Å; α = 76.600(2)°, 77.910(1)°, 79.589(1)°; β = 75.133(2)°, 75.718(1)°, 87.939(1)°; γ = 71.285(2)°, 72.189(1)°, 75.567(1)°; V = 881.78(5), 945.42(3), 1014.34(2) ų for K, Rb, Cs, respectively. The structure of M₄V₂O₃(SO₄)₄ was found to be formed by discrete complex anions V₂O₃(SO₄) ₄ ^4? incorporating two oxygen-bridged vanadium atoms in a distorted octahedral oxygen environment. The sulfate groups are coordinated by the vanadium atoms in the chelating mode with a large scatter of S-O interatomic distances and OSO angles. Every VO₆ octahedron has a short terminal vanadium-oxygen bond with a length of about 1.6Å. The V₂O₃(SO₄) ₄ ^4? complex anions in potassium and rubidium compounds differ from that in Cs₄V₂O₃(SO₄)₄ in the type of symmetry and mutual spatial orientation. The vibrational spectra were presented and interpreted in line with the structural analysis data.     

Synthesis,hydration, and electric properties of chlorine-substituted brownmillerite Ba<Subscript>1.95</Subscript>In<Subscript>2</Subscript>O<Subscript>4.9</Subscript>Cl<Subscript>0.1</Subscript>

Chlorine-substituted brownmillerite Ba_1.95In₂O_4.9C_l0.1 was obtained from barium indate Ba₂In₂O₅ by solid-phase synthesis. The ability to absorb water from the gas phase was confirmed by thermogravimetric studies. The transport properties were studied while varying the thermodynamic parameters of the external environment (T, pO₂, pH₂O). The chloride ions in the oxygen sublattice of barium indate Ba₂In₂O₅ were found to affect the ion conductivity. In a humid atmosphere, the sample exhibited proton conductivity (E _a = 0.54 eV), whose contribution became dominant below 300°C.     

La<Subscript>1.8</Subscript>Sr<Subscript>0.2</Subscript>Ni<Subscript>0.8</Subscript>M<Subscript>0.2</Subscript>O<Subscript>4</Subscript> (M = Fe,Co, or Cu) Complex Oxides: Synthesis,Structural Characterization,and Dielectric Properties

New solid solutions La_1.8Sr_0.2Ni_0.8M_0.2O₄ (M = Fe, Co, or Cu) have been prepared, and their crystal- chemical characteristics and electric properties studied. The studied materials have been shown to have activation-time conductivity. Structural distortions have been found to affect the dielectric properties of ceramic samples. La_1.8Sr_0.2Ni_0.8M_0.2O₄ is observed to have the greatest distortion of АО₉ coordination polyhedra and a higher dielectric constant.     

Osmium thioselenochloride Os<Subscript>2</Subscript>S<Subscript>6</Subscript>Se<Subscript>2</Subscript>Cl<Subscript>8</Subscript>: Synthesis,cluster isolation,and structure

The quaternary thioselenochloride complex Os₂S₆Se₂Cl₈ (I) was obtained by a reaction of OsO₄ with a solution of Se in S₂Cl₂ at 100°C and identified by combination of X-ray diffraction (polycrystalline approach) and cluster framework isolation. A reaction of complex I with melted 4-cyanopyridine (4-CNPy) at 165°C gave the complex Os₂S₂Cl₄(4-CNPy)₄, which confirms the integrity of the binuclear cluster frame-work [Cl₂OsS₂OsCl₂] in complex I.     

Hydrothermal synthesis,characterization, and thermal properties of alumino silicate azide sodalite,Na<Subscript>8</Subscript>[AlSiO<Subscript>4</Subscript>]<Subscript>6</Subscript>(N<Subscript>3</Subscript>)<Subscript>2</Subscript>

First time we report the synthesis, structural characterization and thermal behavior of an unusual N₃ ^? containing alumino-silicate sodalite mineral. Azide sodalite, Na₈[AlSiO₄]₆(N₃)₂ has been synthesized under hydrothermal conditions at 433 K in steel lined Teflon autoclave. The structural and microstructural properties of azide sodalite mineral was characterized by various methods including FT-IR, XRD, SEM, TGA, and MAS NMR. Crystal structure have been refined by Rietveld method in \(P\bar 43n\) space group, indicating that the N₃ ^? sodalite has cubic in lattice. High temperature study was carried out to see the effect of thermal expansion on cell dimension (a ^o) of azide sodalite. Thermal behavior of sodalite was also assessed by thermogravimetric method.     

Interaction of solid electrolyte La<Subscript>0.88</Subscript>Sr<Subscript>0.12</Subscript>Ga<Subscript>0.82</Subscript>Mg<Subscript>0.18</Subscript>O<Subscript>2.85</Subscript> with hydrogen,water vapor,and carbon dioxide

The air,Au/La_0.88Sr_0.12Ga_0.82Mg_0.18O_2.85/Au,air cells are studied by an impedancemetry method before and after a week-long exposure at 700°C to atmospheres of hydrogen, humid air, and carbon dioxide. Blank specimens of the same electrolyte are examined by methods of x-ray diffraction, Raman scattering (RS), and x-ray photoelectron spectroscopy. The fact that the shape of the RS spectra and the shape of the electrode impedance dispersion alter unequivocally suggests that, at the very least, the electrode surface interacts with all the gases. The interaction in question is reversible in the case of hydrogen and carbon dioxide. In the case of water vapor, the interaction is irreversible.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 198–205.Original Russian Text Copyright © 2005 by Shkerin, Kovyazina, Beresnev, Kalashnikova, Martemyanova.This revised version was published online in April 2005 with corrections to the article note and article title and cover date.     

Synthesis,structural, spectral,thermal and comparative biological activity studies of [V<Subscript>2</Subscript>O<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>]

The hydrothermal reaction of a mixture of V₂O₅, VCl₃, 2,5-pyridinedicarboxylic acid and diluted H₂SO₄ for 68 h at 180°C gives a blue colored solution which yields prismatic blue crystals of IV ₂ ^IV O₂(SO₄)₂(H₂O)₆] (1) in 32% yield (based on V). Complex 1 was investigated by means of elemental analysis (C, H and S), TGA, FT-IR, manganometric titration, Single Crystal X-ray Diffraction Methods and also comparative antimicrobial activities. Crystal data for the compound: monoclinic space group P2₁/c and unit cell parameters are a = 7.3850(12) Å, b = 7.3990(7) Å, c = 12.229(2) Å, β = 108.976(12)° and Z = 2. Although structure of 1 as a natural mineral has been previously determined, this work covers new preparation method and full characterization of 1 along with comparison of antibacterial activity between 1 and the commercial vanadium(IV) oxide sulfate hydrate compounds, VOSO₄ · xH₂O (Riedel-de Haën and Alfa Aesar brand names). 1 was evaluated for the antimicrobial activity against gram-positive, gram-negative bacteria, yeasts and mould compared with the commercial VOSO₄ · xH₂O compounds. 1 showed weak activity against bacteria Bacillus cereus, Nocardia asteroides and yeast Candida albicans. A good antimicrobial activity was recorded against Cirtobacter freundii (15 mm). There are only a few reproducible well-defined vanadium(IV) starting materials to use for exploring the synthesis of new materials. VCl₄, VO(acac)₂, VOSO₄ · xH₂O and [V(IV)OSO₄(H₂O)₄] · SO₄ · [H₂N(C₂H₄)₂NH₂] are common starting materials for such applications. In addition to these compounds, 1 can be used as an oxovanadium precursor.     

Preparation,Thermal Behaviour,and Crystal Structure of MgAl<Subscript>2</Subscript>F<Subscript>8</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>

Summary.  Single crystals of MgAl₂F₈(H₂O)₂ have been obtained under hydrothermal conditions (250°C, 14 d) from a starting mixture of AlF₃ and MgAlF₅(H₂O)₂ in a 5% (w/w) HF solution. The crystal structure has been determined and refined from single crystal data (Fmmm (#69), Z = 4, a = 7.2691(7), b = 7.0954(16), c = 12.452(2) ?, 281 structure factors, 27 parameters, R(F ² > 2σ (F ²)) = 0.0282, wR(F ² all) = 0.0885). The obtained crystals were systematically twinned according to (010/100/001) as twinning matrix, reflecting the pseudo-tetragonal metric. The crystal structure is composed of perowskite-type layers built of corner sharing AlF₆ octahedra with an overall composition of AlF₄ ⁻ which are connected via common fluorine atoms of [MgF_4/2(H₂O)_2/1] octahedra. Group-subgroup relations of MgAl₂F₈(H₂O)₂ to WO₃(H₂O)_0.33 and to other M(II)M(III)₂ F₈(H₂O)₂ structures are briefly discussed. Above 570°C, MgAl₂F₈(H₂O)₂ decomposes under elimination of water into α-AlF₃, β-AlF₃, and MgF₂. Received October 29, 2001. Accepted (revised) December 6, 2001     

Structure and properties of Ce<Subscript>3</Subscript>Pd<Subscript>3</Subscript>Bi<Subscript>4</Subscript>, CePdBi,and CePd<Subscript>2</Subscript>Zn<Subscript>3</Subscript>

The intermetallic cerium compounds Ce₃-Pd₃Bi₄, CePdBi, and CePd₂Zn₃ were synthesized from the elements in sealed tantalum ampoules in an induction furnace. The compounds were characterized by X-ray powder and single crystal diffraction: CeCo₃B₂ type (ordered version of CaCu₅), P6/mmm, a = 538.4(4), c = 427.7(4) pm, wR2 = 0.0540, 115 F ² values, 9 variables for CePd₂Zn₃ and Y₃Au₃Sb₄ type, I \({\bar 4}\)3d, a = 1005.2(2) pm, w R2 = 0.0402, 264 F ² values, 9 variables for Ce₃Pd₃Bi₄, and MgAgAs type, a = 681.8(1) pm for CePdBi. The bismuthide structures are build up from three-dimensional networks of corner-sharing PdBi₄ tetrahedra with Pd–Bi distances of 281 (Ce₃Pd₃Bi₄) and 296?pm (CePdBi), respectively. The cerium atoms are located in larger voids of coordination number 12 (Ce₃Pd₃Bi₄) and 10 (CePdBi). In CePd₂Zn₃ the cerium atoms fill larger channels within the three-dimensional [Pd₂Zn₃] network with 18 (6 Pd + 12 Zn) nearest neighbors. The three compounds contain stable trivalent cerium with experimental magnetic moments of μ_eff = 2.70(2), 2.48(1), and 2.49(1) μ_B/Ce atom for CePd₂Zn₃, Ce₃Pd₃Bi₄, and CePdBi, respectively. Susceptibility and specific heat data gave no hint for magnetic ordering down to 2.1?K.     

Composition of the gas phase over Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and the enthalpies of atomization of AlO,Al<Subscript>2</Subscript>O,and Al<Subscript>2</Subscript>O<Subscript>2</Subscript>

The A1, O, AlO, A1₂O, Al₂O₂, WO₂, and WO₃, partial pressures in the vapor over Al₂O₃ in a tungsten Knudsen effusion cell between 2300 and 2600 K were derived from A1⁺, O⁺, AlO⁺, A1₂O⁺, Al₂O₂⁺, WO₂⁺, and WO₃⁺, ion intensities. The mass spectrometer was calibrated against the equilibrium constant of the WO₃(g) = WO₂(g) + O(g) reaction. Refined values of the ionization cross sections of AlO and A1₂O₂ were used in the partial pressure calculations. The enthalpies of atomization of aluminum suboxides were determined to be Δ_at H ^o(AlO, g, 0) = 510.7 ± 3.3 kJ mol⁻¹, Δ_at H ^o(Al₂O, g, 0) = 1067.2 ± 6.9 kJ mol⁻¹, and Δ_at H ^o(Al₂O₂, g, 0) = 1556.7 ± 9.9 kJ mol⁻¹.     

Ternary reciprocal systems Na,K||BO<Subscript>2</Subscript>,CO<Subscript>3</Subscript> and Na,K||BO<Subscript>2</Subscript>,Cl

The phase diagrams of the ternary reciprocal systems Na,K||BO₂,CO₃ and Na,K||BO₂,Cl were studied for the first time by a calculation-experimental method and by differential thermal analysis. Analytical models of phase equilibrium states were derived, and the coordinates of eutectics were found to be (680°C, 32 mol % NaBO₂, 68 mol % KCl) and (648°C, 9 mol % NaBO₂, 45.5 mol % NaCl, 45.5 mol % KCl). Binary solid solutions based on metaborates and carbonates of sodium and potassium were shown to be stable. The possibility of synthesizing tungsten oxide bronzes in a eutectic melt in the ternary system NaBO₂–NaCl–КCl was revealed.     

Synthesis,structure, and properties of M<Subscript>3</Subscript>VO<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>2</Subscript> (M = Rb,Cs)

Vanadium(V) complexes of general composition M₃VO₂(SO₄)₂ (M = Rb, Cs) were synthesized by a solid-state route. The individuality of the synthesized compounds was proved by X-ray and neutron diffraction, vibrational spectroscopy, and microscopic analysis. The X-ray diffraction patterns of M₃VO₂(SO₄)₂ were indexed to fit the monoclinic system (space group P2/c, Z = 4) with the following unit cell parameters: a = 11.6487(2) Å, b = 8.4469(2) Å, c = 12.1110(2) Å, β = 109.483(1)°, V = 1123.43 ų (Rb); a = 12.0546(3) Å b = 8.7706(2) Å, c = 12.6496(3) Å, β = 109.843(2)°, V = 1257.99 ų (Cs). In the crystal structure of M₃VO₂(SO₄)₂, [VO₂(SO₄)₂]^3? complex anions can be discerned in which the vanadium atom is surrounded by five oxygen atoms: two oxygen atoms form short terminal V–O bonds, and three oxygen atoms are from the two sulfato groups, one of which acts as a monodentate ligand and the other acts as a bidentate chelating ligand.     

Synthesis,structure, and properties of V<Subscript>2</Subscript>O<Subscript>3</Subscript>(XO<Subscript>4</Subscript>)<Subscript>2</Subscript> (X = S,Se)

Compounds described as V₂O₃(XO₄)₂, where X = S or Se, were prepared from vanadium(V) oxide mixtures with concentrated sulfuric and selenic acids. The physicochemical properties of the products were studied; for V₂O₃(SeO₄)₂, the crystal structure was determined by powder X-ray diffraction and neutron diffraction, and its key differences from the structure of V₂O₃(SO₄)₂ were identified. V₂O₃(SeO₄)₂ crystallizes in the monoclinic system with the unit cell parameters a = 15.3831(2)Å, b = 5.54096(5)Å, c = 9.71644(7)Å, β = 111.886(1)°, V = 768.51ų, space group C2/c (no. 15).     

Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>/BiFeO<Subscript>3</Subscript> heterostructure: preparation,characterization, and photocatalytic activity

Bi₂O₃/BiFeO₃ composite was successfully fabricated by a conventional sol–gel method and structural properties were characterized based on X-ray diffractometer, scanning electron microscope, transmission electron microscope, energy-dispersive X-ray analyzer, nitrogen adsorption–desorption measurement, and UV–visible diffuse reflectance spectroscopy. Bi₂O₃/BiFeO₃ had a good absorption for visible light, which was benefit to photocatalytic activity. The highest degradation efficiency was obtained when the content of Bi₂O₃ in Bi₂O₃/BiFeO₃ was 63.9%. Effect of experimental conditions was investigated, and the highest photocatalytic activity of Bi₂O₃/BiFeO₃ was observed at photocatalyst dosage of 0.5 g/L, initial BPA concentration of 10 mg/L, and solution pH of 6.3. Bi₂O₃/BiFeO₃ photocatalyst exhibited enhanced photocatalytic activity for BPA, and the reaction rate constant over Bi₂O₃/BiFeO₃ composite was 2.23, 3.65, and 8.71 times higher than that of BiFeO₃, Bi₂O₃ and commercial TiO₂ (P25), respectively. Bi₂O₃/BiFeO₃ showed high photocatalytic activity after three cycles, suggesting that it was a stable photocatalyst. The possible photocatalytic mechanism has been discussed on the basis of the theoretical calculation and the experimental results. The hydroxyl and superoxide radicals together with photogenerated holes played significant roles in the photocatalytic reaction.     

Reactions of Cr atoms with NO,N<Subscript>2</Subscript>O,CO<Subscript>2</Subscript>, NO<Subscript>2</Subscript>, and SO<Subscript>2</Subscript> molecules

Experimental results on the interaction of Cr atoms with various oxygen-containing molecules (NO, N₂O, CO₂, NO₂, and SO₂) at high temperatures (>1000 K) are presented. It is demonstrated that activation barrier for spin-forbidden reactions is higher, all other things being equal. For the reaction of Cr atoms with N₂O, an interpolated temperature dependence of the rate constant, based on the high-temperature measurements conducted in the present work and the published low-temperature data, is proposed.     

Synthesis,molecular, crystal and electronic structure of [RuCl<Subscript>2</Subscript>(PPh<Subscript>3</Subscript>)<Subscript>2</Subscript>(3,5-Me<Subscript>2</Subscript>HPz)<Subscript>2</Subscript>]

The reaction of [RuCl₂(PPh₃)₃] complex with dimethylpyrazole has been examined. A new ruthenium complex—[RuCl₂(PPh₃)₂(3,5-Me₂HPz)₂] has been obtained and characterized by IR, ¹H NMR and UV-VIS measurements. Crystal and molecular structure of the complex has been determined. The electronic structure of the complex has been calculated by TDDFT method.