Structure and charge-transport properties of LnBaCuCoO<Subscript>5 + δ</Subscript> (Ln = Y,Dy) cuprocobaltites

LnBaCuCoO_{5 + δ} (Ln = Y, Dy) cuprocobaltites were prepared. Their unit cell parameters were determined and their thermal expansion, electrical conductivity (σ), and Seebeck coefficient (S) were studied in air in the range 300–1100 K. The compounds have tetragonal structures (space group P4/mmm). Their unit cell parameters are a = 0.3867(2) nm, c = 0.7550(7) nm, V = 112.9(2) × 10^?3 nm³ for YBaCuCoO_4.98; and a = 0.3872(2) nm, c = 0.7562(7) nm, V = 113.4(2) × 10^?3 nm³ for DyBaCuCoO_5.01. They are p-type semiconductors. The electrical conductivity of DyBaCuCoO_{5 + δ} is slightly lower and its Seebeck coefficient is 1.5–2 times higher than the respective values for YBaCuCoO_{5 + δ} apparently because of different electronic configurations of the rare-earth cations in LnBaCuCoO_{5 + δ} (4d ⁰ for Y³⁺ and 4f ⁹ for Dy³⁺). Dilatometric measurements show that the LnBaCuCoO_{5 + δ} phases in the range 300–1100 K do not experience structural phase transitions, and their linear thermal expansion coefficients (LTEC) are 14.3 × 10^?6 K^?1 for Ln = Y and 14.7 × 10^?6 K^?1 for Ln = Dy.     

Structure of bismuth oxoborate Bi<Subscript>4</Subscript>B<Subscript>2</Subscript>O<Subscript>9</Subscript> at 20, 200, and 450°C

Single crystals of bismuth oxoborate Bi₄B₂O₉ have been grown by slowly cooling the melt of a stoichiometric Bi₂O₃ + H₃BO₃ mixture. The structure of the borate (monoclinic space group P2₁/c, a = 11.107 Å, b = 6.629 Å, c = 11.044 Å, β = 91.04°, Z = 4) has been studied at 20, 200, and 450°C. The structure is described not only in terms of full BiO₆ ^? and BiO₇ polyhedra but also in terms of truncated BiO₃ ^? and BiO₄ ^? polyhedra and BO₃ triangles, as well as oxo-centered OBi₃ triangles and OBi₄ tetrahedra. It is shown that both the B-O and Bi-O bond lengths are practically unaffected by temperature. Only the angles between polyhedra change with temperature, being responsible for the strong anisotropy of Bi₄B₂O₆ thermal expansion, which was measured by high-temperature powder X-ray diffraction: α₁₁ = 20, α₂₂ = 15, α₃₃ = 6 × 10^?6 °C^?1, and μ = (c, α₃₃) = ?19°.     

Apparent Molar Volumes of Aqueous Solutions of Magnesium Tetraborate from 283.15 to 363.15 K and 0.1 MPa

Densities for aqueous solutions of magnesium tetraborate MgB₄O₇(aq) at the molalities of (0.00556–0.03341) mol·kg^?1 were measured with an Anton Paar Digital vibrating-tube densimeter at temperature intervals of 5 K from 283.15 to 363.15 K and 0.1 MPa. Apparent molar volumes were obtained based on the experimental density data, and the 3D diagrams of the apparent molar volume (V _? ) of MgB₄O₇(aq) against temperature (T) and molality (m) were plotted. On the basis of the Vogel–Tamman–Fulcher equation, the coefficients of the correlation equation for densities of MgB₄O₇(aq) against temperature and molality were parameterized. According to the Pitzer ion-interaction model of the apparent molar volume, the temperature correlation equations of Pitzer single-salt parameters F(i,p,T)?=?a₀?+?a₁?×?T?+?a₂?×?T ²?+?a₃/T?+?a₄?×?ln(T)?+?a₅?×?T ³ (where T is temperature in Kelvin, a _i are model parameters) for MgB₄O₇ were obtained for the first time.     

High-temperature heat capacity and thermodynamic properties of pyrovanadate Pb<Subscript>2</Subscript>V<Subscript>2</Subscript>O<Subscript>7</Subscript> and orthovanadate Pb<Subscript>3</Subscript>(VO<Subscript>4</Subscript>)<Subscript>2</Subscript>

The heat capacities of Pb₂V₂O₇ and Pb₃(VO₄)₂ as a function of temperature in the range 350–965 K have been studied by the differential scanning calorimetry method. The C_P = f(T) curve for Pb₂V₂O₇ is described by the equation C_p = (230.76 ± 0.51) + (73.60 ± 0.50)×10^-3T ? (18.38 ± 0.54)×10⁵T^-2 in the entire temperature range. For Pb₃(VO₄)₂, there is a well-pronounced extreme point in the C_P = f(T) curve at T = 371.5 K, which is caused by the existence of a structural phase transition. The thermodynamic properties of the oxide compounds have been calculated.     

Kinetics of thermal reaction HOCl ⇄ H(<Superscript>2</Superscript><Emphasis Type="Italic">S</Emphasis>) + OCl(<Emphasis Type="Italic">X</Emphasis><Superscript>2</Superscript>Π<Subscript><Emphasis Type="Italic">i</Emphasis></Subscript>) in gas phase

The kinetics of gas reaction \(HOCl\underset{{k_r }}{\overset{{k_f }}{\longleftrightarrow}}H(^2 S) + OCl(X^2 \Pi _i )\) was analyzed by the MP4 method. In the temperature range of 100–373 K the rate constants k _f and k _r and equilibrium constant K were changed from 1.10 × 10^?220 to 1.17 × 10^?52 s^?1, from 2.89 × 10^?16 to 1.68 × 10^?5s^?1 and from 3.80 × 10^?205 to 6.96 × 10^?48 respectively. In the above temperature range, the activation energy of the forward reaction (E _f) is 105.05 kcal/mol. In the same temperature interval there are two kinetic domains for the reverse reaction with activation energies (E _r1 = 5.53 kcal/mol when T is 100–273 K and E _r2 = 14.50 kcal/mol when T is 273–373 K, respectively.     

Interaction between oxygen and polycrystalline palladium at O<Subscript>2</Subscript> pressures of 10<Superscript>−6</Superscript>–10 Pa

The interaction between oxygen and polycrystalline palladium (Pd(poly)) at \(P_{O_2 } \) = 2.6 × 10^?6–10 Pa and T = 300–1300 K was studied by the thermal desorption (TD) method. The interaction between O₂ and Pd(poly) is governed by the O₂ pressure and the sample temperature. At low pressures of \(P_{O_2 } \) (≤1.3 × 10^?5 Pa), O₂ is chemisorbed dissociatively on the Pd(poly) surface. During chemisorption, the O_ads-surface bond energy and the O₂ sticking coefficient gradually decrease as the surface coverage θ increases. At \(P_{O_2 } \) ≥ 10^?2 Pa and T ≤ 500 K, after the saturation of the O_ads layer (θ ～ 0.5), O_ads atoms penetrate under the surface layer of the metal to form surface palladium oxide. At \(P_{O_2 } \) ≥ 1 Pa and T > 500 K, after the saturation of the surface oxide film 2 ML in thickness (n ～ 2), O_ads atoms penetrate into the oxide film and then into the subsurface palladium layer and diffuse deep into the metal bulk. As a result, the oxygen uptake at 700 K is n ～ 50. Upon heating, the surface oxides decompose, desorbing O₂, which gives rise to a low-temperature TD peak with T _max = 715 K. The release of oxygen inserted in the subsurface layers of palladium shows itself as a distinct high-temperature TD peak with T _max ≥ 750 K.     

The kinetics of reduction of palladium (II) complexes with β-alanine at dropping mercury electrode and the complexes’ stability constants

By using dc and ac polarography, the kinetics of electroreduction of the palladium (II) complexes with β-alanine at a dropping mercury electrode was studied in solutions with the palladium (II) concentration from 2 × 10^?5 to 2 × 10^?4 M and variable β-alanine and sodium perchlorate concentrations (pH 6–12). One polarographic wave was observed in solutions with pH 9 and 10 at the β-alanine overall concentration of c _βala = 1 × 10^?3 to 5 × 10^?2 M; two waves, at lower pH or higher c _βala. It was concluded on the formation of different forms of palladium (II) complexes in the studied solutions; the complexes contained two to four β-alanine coordinated anions. Using the limiting diffusion currents for the two waves at pH 9–11 and c _βala = 0.1 and 0.5 M, the stepwise stability constant for the Pd(βala) ₄ ^2? complex was calculated. Using two ac peaks observed at pH 7–8 and c _βala = 1 × 10^?2 to 0.1 M, the stepwise stability constant for the Pd(βala) ₃ ^? . was calculated. The perchlorate ions adsorbed at the dropping mercury electrode, as well as βala^? anions at their higher concentrations, hamper the electroreduction of the palladium (II) complexes with β-alanine.     

Synthesis and X-ray diffraction study of ferrites ErM<Superscript>I</Superscript>Fe<Subscript>2</Subscript>O<Subscript>5</Subscript> (M<Superscript>I</Superscript> = Li,Na, K,Cs)

Ferrites of composition ErM^IFe₂O₅ (M^I = Li, Na, K, Cs) were synthesized by a solid-phase method. The structure of the ferrites was for the first time studied by X-ray powder diffraction. Crystal systems, unit cell parameters, and X-ray and pycnometric densities were determined. For ErLiFe₂O₅, a = 10.510 Å, c = 14.270 Å, V°= 1616.16 ų, Z = 16, V _subcell ^° = 101.01 ų, ρ_x = 6.01 g/cm³, ρ_pyc = 5.97 ± 0.04 g/cm³; for ErNaFe₂O₅, a = 10.519 Å, c = 15.510 Å, V° = 1759.56 ų, Z = 16, V _subcell ^° = 109.90 ų, ρ_x = 5.77 g/cm³, ρ_pyc = 5.72 ± 0.08 g/cm³; for ErKFe₂O₅, a = 11.050 Å, c = 15.480 Å, V° = 1937.33 ų, Z = 16, V _subcell ^° = 121.08 ų, ρ_x = 5.46 g/cm³, ρ_pyc = 5.41 ± 0.04 g/cm³; and for ErCsFe₂O₅, a = 10.78 Å, c = 16.01 Å, V° = 1905.37 ų, Z = 16, V _subcell ^° = 119.09 ų, ρ_x = 6.86 g/cm³, ρ_pyc = 6.61 ± 0.01 g/cm³.     

The sol–gel chromium-modified V<Subscript>6</Subscript>O<Subscript>13</Subscript> as a cathodic material for lithium batteries

A new V₆O₁₃-based material has been synthesized via the sol–gel route. This sol–gel mixed oxide has been obtained from an appropriate heat treatment of the chromium-exchanged V₂O₅ xerogel performed under reducing atmosphere. This new compound, with the chemical formula Cr_0.36V₆O_13.50, exhibits a monoclinic structure (C2/m) with the following unit cell parameters, a=11.89 Å, b=3.68 Å, c=10.14 Å, β=101.18°. The electrochemical characterization of this compound has been performed using galvanostatic discharge–charge experiments in the potential range 4–1.5 V and completed by ac impedance spectroscopy measurements. It exhibits a specific capacity of about 370 mAh g^?1, which makes the compound Cr_0.36V₆O_13.50 the best one in the V₆O₁₃-based system: 85% of the initial capacity (315 mAh g^?1) after the 35th cycle is still available at C/25 without any polarization. From impedance spectroscopy, a high kinetics of Li transport (D _Li=1.8×10^?9 cm² s^?1) is found at mid-discharge.     

Crystal and molecular structure of the Fu-4,4O’-bipyridyl-bis[<Emphasis Type="Italic">trans</Emphasis>-C,O-nitrate-2-(2O’-thienyl-3-ido)pyridine-palladium] complex

The synthesis and determination of the crystal and molecular structure of the binuclear complex fu-4,4′-bipyridyl-bis-[trans-C,0-nitrate-2-(2′-thienyl–3-ido)pyridine-palladium] is described (C₂₈H₂₀N₆O₆Pd₂S₂: a = 12.3914(11) Å, b = 9.8929(7) Å, c = 12.4058(12) Å, α = 90(0)β, ß = 105.440(40)α, γ = 90(0)α, V = 1465.9(0) ų, monoclinic symmetry, P2 ₁/n (14), Z = 4, d _x = 1.843 g/cm³ ). The pyridine rings of 4,4′-bipyridyl are shown to be in the orthogonal position with respect to the coordination planes of palladium centers both in the solid state and solution     

The diffusion of oxygen and ion transport in lanthanum cobaltite LaCoO<Subscript>3-δ</Subscript>

The chemical diffusion coefficient of oxygen vacancies and oxygen ion conductivity in lanthanum cobaltite LaCoO₃ were determined by the polarization method as functions of oxygen partial pressure \(p_{O_2 } \) (atm) and temperature T(K) over the ranges ?4 ≤ log \(p_{O_2 } \) ≤ 0 and 1173 K ≤ T ≤ 1323 K. The mobilities (cm²/(V s)) of oxygen vacancies calculated over the temperature range studied satisfy the inequalities 1.8 × 10^?5 ≤ \(v_{v_0 } \) ≤ 3.4 × 10^?5. The transfer numbers of oxygen vacancies were calculated. These numbers change depending on oxygen partial pressure over the range 5 × 10^?7 ≤ t ₀ ≤ 1 × 10^?5. The activation energy of self-diffusion of oxygen vacancies was found to be E _a= 104 ± 10 kJ/mol (1.1 ± 0.1 eV).     

Hydrothermal synthesis and crystal structure of a tungstovanadate: [4,4′-bipyH<Subscript>2</Subscript>][4,4′-bipyH]<Subscript>2</Subscript>[VW<Subscript>12</Subscript>O<Subscript>40</Subscript>] · 4,4′-bipy · 7.5H<Subscript>2</Subscript>O

An organic-inorganic hybrid Keggin compound, [4,4′-bipyH₂][4,4′-bipyH]₂[VW₁₂O₄₀] · 4,4′-bipy · 7.5H₂O (bipy-bipyridine) (1), has been prepared under hydrothermal conditions and characterized by IR spectroscopy, single crystal X-ray diffraction, thermal analysis, and ESR spectroscopy. 1 crystallized in the monoclinic space group P2₁/c with a = 18.7350(15) Å, b = 14.0253(12) Å, c = 26.434(2) Å, β= 105.0810(10)°, V = 6706.6(10) ų and Z = 4. The crystal structure of 1 consists of diprotonated and monoprotonated 4,4′-bipyridine cations, free 4,4′-bipyridine molecule, lattice water molecules, and a typical Keggin-type polyoxoanion [VW₁₂O₄₀]^4?. The polyoxoanion is constructed by four {W₃O₁₆} trinuclear groups, each of which is made up of three edge-sharing {WO₆} octahedra, and the {VO₄} tetrahedron is in the center of the cage.     

Structure of cyano-bridged Eu(III)—Co(III) bimetallic assembly and its application to photophysical verification of photomagnetic phenomenon

New crystal structure of Eu(DMF)₄(H₂O)₃Co(CN)₆·H₂O (DMF = N,N′-dimethylformamide) (Eu-Co) has been determined to be monoclinic, P2(1)/n, a = 19.796(12) Å, b = 8.862(11) Å, c = 17.525(10) Å, β = 96.26(5)°, V = 3056(5) ų, Z = 4. The Eu(III) ion adopts an antiprismatic eight-coordination and forms a cyano bridge with r(Eu-N) = 2.496(7) Å and Θ(Eu-N-C) = 165.7(7)° to the Co(III) ion. The complex exhibits some common features with the Eu-Fe complex. Diffuse reflectance electronic spectra and magnetic susceptibility of Eu-Cr, Eu-Mn, Eu-Fe, and Eu-Co complexes were compared. By substituting the metal ions, both electronic and structural features affected the charge transfer bands and superexchange interactions concerning cyanide ligands. In addition, only Eu-Co exhibited ⁵ D ₀ → ⁷ F ₂ and ⁵ D ₀ → ⁷ F ₁ luminescence bands at 16300 cm^?1 and 16900 cm^?1, respectively at 298 K (λ_ex = 360 nm (27000 cm^?1)), because quenching by cyano-bridged ions did not prevent Eu(III) ion from exhibiting emission. Thus, only Eu-Co may be suitable for verification of an assumption of mechanism concerning drastic photoinduced magnetic changes for Nd-Fe. Merely small decrease of magnetization was observed for Eu-Co after UV light irradiation at 2.0 K. This result was attributed to slight structural changes around cyano bridges without transitions of spin states.     

Synthesis,structure, and properties of a new 3D hydrogen-bonded porous coordination polymer

A new coordination polymer, [Cd(HMal)(Bipy)(H₂O) · 2H₂O (I) (H₃Mal is malic acid, Bipy is 4,4′-bipyridine), has been synthesized from H₃Mal and Bipy under hydrothermal conditions and characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction. The X-ray diffraction analysis reveals that I (C₁₄H₁₆N₂O₇Cd) crystallizes in the orthorhombic system, space group Ibam. The adjacent cadmium(II) atoms were first interconnected by the HMal ligands via carboxylate oxygen atoms and its adjacent hydroxyl group to generate an infinite zigzag [Cd(HMal)] _n chain, which are further linked by Bipy ligands to form a 2D wavelike layer. Interestingly, the adjacent layers are further connected via hydrogen bonds, giving rise to a 3D porous framework with a cross-sectional area of 11.690 × 9.326 Ų. The unit cell parameters for I: a = 8,457(1), b = 22.030(7), c = 23.066(7) V = 4297(2) ų, Z = 4.     

Electronic and crystal structure of (N-CH<Subscript>3</Subscript>-2,2′-bipyridinium)(dodecahydro-dicarba-<Emphasis Type="Italic">nido</Emphasis>-undecaborate)

The compound [N-Me-2,2′-Bipy]⁺[C₂B₉H₁₂]^?-(N-CH₃-2,2′-bipyridinium)(dodecahydro-dicarba-nidoundecaborate) has been synthesized, and its structure has been determined. The compound was defined by IR, ¹¹B and ¹⁴N NMR, and X-ray photoelectron spectroscopy. Crystal data: C₁₃H₂₃B₉N₂, M = 304.62, monoclinic crystals, space group P2₁/c, a = 11.840(4) Å, b = 10.051(3) Å, c = 15.573(6) Å, β = 102.43(3)°, V = 1809.8(10) ų, Z = 4, d _calc = 1.118 g/cm³, R = 0.0607.     

Synthesis,crystal structure,and kinetics of thermal decomposition of the Zn(II) complex with vanillin

A complex [Zn(C₈H₇O₃)₂(H₂O)₂] (C₈H₈O₃ is vanillin) has been synthesized and characterized by IR, elemental analysis, and X-ray diffraction single-crystal analysis. The crystals are monoclinic, space group C2/c, a = 22.236(8) Å, b = 10.594(2) Å, c = 7.8190(16) Å, α = 89.90(3)°, β = 106.87(4)°, γ = 89.99(3)°, V = 1762.6(8) ų, Z = 4, F(000) = 832, S = 1.079, ρ _c = 1.521g cm^?3, R = 0.0221, R _w = 0.0604, μ = 1.433 mm^?1. The Zn²⁺ ion is six-coordinated with a distorted octahedron geometry. The complex forms a three-dimensional network through intermolecular hydrogen bonds. The thermal decomposition kinetics of the complex for the second stage was studied under non-isothermal conditions by the TG and DTG methods. The kinetic equation can be expressed as dα/dt = Ae^?E/RT 2(1 ? α)[1 ? ln(1 ? α)]^1/2. The kinetic parameters (E, A), activation entropy ΔS ^≠, and activation free-energy ΔG ^≠ were also gained.     

Structure and thermal properties of heterometallic complexes for chemical vapor deposition of Cu–Pd films

Novel volatile heterocomplex compounds based on copper(II) and palladium(II) fluorinated β-diketonates are studied. The crystals of the synthesized compounds are shown to be composed of 1D coordination polymers in the form of chains of alternating molecules of monometallic complexes. The crystallographic data for [Cu(hfa)₂?Pd(zif)₂] are as follows: C₂₆H₂₂F₁₈O₁₀CuPd, P2₁/c, a = 7.9947(18) Å, b = 19.277(4) Å, c = 13.609(3) Å, β = 118.298(15)°, V = 1846.7(7) ų, Z = 2, d = 1.810 g/cm³. The thermal properties of the compounds are examined by TG-DTA and vacuum sublimation. The complexes are studied as the precursors for producing copper-palladium alloy films by chemical vapor deposition. It is demonstrated that bimetallic alloy coatings with a ratio Cu/Pd = 1:1 can be prepared from [Cu(hfa)₂?Pd(zif)₂].     

Preparation specifics and properties of AMn<Subscript>3</Subscript>V<Subscript>4</Subscript>O<Subscript>12</Subscript> (А = Ca,Ce, and Sm) high-pressure phases

Perovskite-like phases AMn₃V₄O₁₂ (A = Ca, Ce, and Sm) were prepared under borothermic conditions (p = 7.0–9.0 GPa, T = 700–1100°C). Their X-ray diffraction structure (space group Im \(\bar 3\), Z = 2) was determined, and unit cell parameters were calculated: for CaMn₃V₄O₁₂: а = 7.40824(3) Å, for SmMn₃V₄O₁₂: а = 7.45280(8) Å, and for CeMn₃V₄O₁₂: а = 7.46965(4) Å. The temperature-dependent electrical resistivity (10–300 K) and magnetic susceptibility (2–300 K) of the prepared phases were studied.     

Experimente und Modellrechnungen zum chemischen Transport von V2O5 mit NH4Cl

Experiments and Calculations for the Chemical Transport of V₂O₅ with NH₄Cl For the chemical transport of V₂O₅ in a temperature gradient (T₂ – T₁ = ΔT = 100 K) the influence of temperature (T₂ = 770 K to 970 K) on the transport rate n′(V₂O₅) using an admixture of 2 to 8 mg NH₄Cl (2,3 to 9,2 × 10^?3 mmol/cm³) has been investigated. Also the dependence of n′ on the admixture of the transport agent has been examined from 2 to 52 mg NH₄Cl (T₂ = 850 K, T₁ = 750 K). We observed that n′ increases with increasing temperature and increasing admixture of NH₄Cl. The model calculations show the opposite tendency of the dependence on temperature; for all experiments the value of n′ was lower by a factor of 10 to 320 than the calculated one. These deviations indicate, that our knowledge on the gas phase of this system is incomplete.     

X-Ray diffraction data for new ferrites ErMFe<Subscript>2</Subscript>O<Subscript>5</Subscript> (M = Li,Na, K)

New ferrites ErMFe₂O₅ (M = Li, Na, K) were synthesized from erbium and iron(III) oxides and lithium, sodium, and potassium carbonates by solid-state annealing. According to X-ray powder diffraction, these compounds crystallize in the orthorhombic system with the following unit cell parameters: ErLiFe₂O₅, a = 10.510 Å, b = 10.776 Å, c = 14.270 Å, V ⁰ = 1616.16 ų; Z = 16, V _subcell ⁰ = 101.01 ų, ρ_X = 6.01 g/cm³, ρ_pycn = 5.97 ± 0.05 g/cm³; ErNaFe₂O₅, a = 10.519 Å, b = 10.785 Å, c = 15.510 Å, V ⁰ = 1759.56 ų, Z = 16, V _subcell ⁰ = 109.90 ų, ρ_X = 5.77 g/cm³, ρ_pycn = 5.72 ± 0.08 g/cm³; ErKFe₂O₅, a = 10.050 Å, b = 11.320 Å, c = 15.480 Å, V ⁰ = 1937.33 ų, Z = 16, V _subcell ⁰ = 121.08 ų, ρ_X = 5.46 g/cm³, ρ_pycn = 5.41 ± 0.04 g/cm³.