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The copper borate Li 2 Pb 2 CuB 4 O 10 has been synthesized in air by the standard solid-state reaction at temperature in the range 550–650 °C and the structure of Li 2 Pb 2 CuB 4 O 10 was determined by single-crystal X-ray diffraction. Li 2 Pb 2 CuB 4 O 10 crystallizes in the monoclinic space group C 2/ c (no. 15) with a = 16.8419(12), b = 4.7895(4), c = 13.8976(10) A, and β = 125.3620(10)°, V = 914.22(12) A 3 , and Z = 4, as determined by single-crystal X-ray diffraction. The Li 2 Pb 2 CuB 4 O 10 structure exhibits isolated units of stoichiometry [CuB 4 O 10 ] 6− that are built from CuO 4 distorted square planes and triangular BO 3 groups. The IR spectroscopy and thermal analysis investigations of Li 2 Pb 2 CuB 4 O 10 are also presented.

New solid solution crystals of (Mg 1− x Fe x )(Mo 2− x V x )O 7 (0.13≤ x ≤0.47) were grown from MgO–Fe 2 O 3 –V 2 O 5 –MoO 3 melts. Single crystal X-ray diffraction studies reveal that the structure consists of (Mg/Fe) 2 O 10 octahedral dimers and [(Mo 2− x V x )O 7 ] (2+ x )− tetrahedral clusters. The structure contains (V/Mo)O oxo double bonds similar to MgMo 2 O 7 and FeVMoO 7 . Equimolar co-substitution of V 5+ for Mo 6+ and Fe 3+ for Mg 2+ avoids the creation of any ion vacancies or interstitials and generates disordered cation sites. Crystal data: for (Mg 0.87 Fe 0.13 )(Mo 1.87 V 0.13 )O 7 , monoclinic, space group P 2 1 / n (No. 14), with a =8.3356(6) A, b =9.1079(6) A, c =8.5086(6) A, β =111.927(1)° and Z =4; for (Mg 0.53 Fe 0.47 )(Mo 1.53 V 0.47 )O 7 , monoclinic, space group P 2 1 / n (No. 14), with a =8.2766(6) A, b =9.0208(7) A, c =8.4817(6) A, β =112.144(1)° and Z =4.

FeMg 2 V 3 O 11 crystals grown from a MgO/Fe 2 O 3 /V 2 O 5 melt crystallize in the triclinic space group P-1 with parameters: a =6.434(1) A, b =6.806(1) A, c =10.085(1) A, α =97.44(1)°, β =103.44(1)°, γ =101.56(1)° and Z =2. FeZn 2 V 3 O 11 crystals grown from a ZnO/Fe 2 O 3 /V 2 O 5 melt also crystallize in P-1 with similar parameters: a =6.455(1) A, b =6.834(1) A, c =9.988(1) A, α =97.65(1)°, β =102.61(1)°, γ =101.26(1)° and Z =2. Both are isostructural with GaZn 2 V 3 O 11 , and susceptibility measurements reveal that all iron is high spin d 5 . In FeMg 2 V 3 O 11 , Fe 3+ is distributed non-statistically with Mg 2+ on octahedral and bipyramidal sites. In FeZn 2 V 3 O 11 , Fe 3+ is found only on the octahedral sites and Zn 2+ exclusively occupies the bipyramidal sites.

The equilibrium oxygen content was measured in the solid solution YBa 2 Cu 3 x Zn x O 6+ δ , where x =0, 0.1, 0.2, 0.3, in the temperature range 600–825°C and oxygen pressure between 10 −5 and 1.0 atm. The concentration dependencies of the partial molar enthalpy Δ H °( δ ) and entropy Δ S °( δ ) of oxygen were determined. A decrease of both Δ H °( δ ) and Δ S °( δ ) at δ

Experimental data, more detailed and complete than previously available, for thermopower and conductivity in YBa2Cu3O6+x was obtained in the temperature range 600 to 850°C and oxygen content varying in the limits 0.1≤x≤0.8 under equilibrium pressure of oxygen. The concentration dependencies of conductivity and thermopower were derived using an equilibrium P(O2)–T–x diagram. Isothermal plots of thermopower versus the logarithm of conductivity show unusual features in the extrinsic hole regime, i.e. a small inward curvature, an anomalously small slope and a weak temperature dependence were observed. The decrease in the oxygen content at high temperature results in the expected transition to intrinsic behavior and the contribution of electrons to the conductivity. The results obtained have been interpreted in the framework of the band structure comprised of two narrow bands on the background of two broad bands. The main influence of the broad bands is on the position of the chemical potential, whereas the location of the narrow bands relative to the chemical potential of the electrons impacts the electron transport.

Reduction of polycrystalline and crystalline magnesium orthovanadate Mg3V2O8 by hydrogen was investigated in the temperature range of 560–920°C. A single crystal of orthorhombic Mg3V2O8 with a cation-deficient-spinel structure (25% of the magnesium atoms on octahedral sites are vacant) was transformed into cubic Mg3V2O6 which has a cation-stuffed-spinel structure (8a and 16c sites were partially occupied by magnesium and 16d sites were fully occupied by magnesium and vanadium) at 560°C in 7% H2 in N2.

Single crystals of Mn2.47V0.94Mo1.06O8 were grown in a MnO/V2O5/MoO3 melt under a nitrogen atmosphere (orthorhombic, space group Pnma (No. 62), a=5.167(2) A, b=10.580(3) A, c=17.868(4) A, and Z=6). The crystallization, composition, and quality of the crystals were largely influenced by the composition of the melt, temperature and the oxygen partial pressure.

Single crystals of Zn3.77V1.54Mo1.46O12 were grown in a ZnO/V2O5/MoO3 melt. The colorless needles were determined to be orthorhombic, space group P212121 (No. 19), a=5.048 (4) A , b=10.400 (2) A , c=17.560 (7) A , V=921.9(6) A 3 , and Z=4. One type of zinc cation in the structure exhibits trigonal prismatic coordination, and relatively large distortions of the ZnO bond lengths in the trigonal prisms reduce the symmetry from Pnma (centrosymmetric) to P212121 (acentric).

The phase relationships in the pseudobinary MgMoOMg3V2O8 system have been determined by differential thermal analysis and X-ray diffraction analysis. The intermediate compound Mg2.5VMoO8 was found to exhibit a considerable solid solution Mg2.54V1.08Mo0.92O8 (−0.05 ≤ x ≤ 0.05) at 1100°C in air. Single crystals with composition of Mg2.54V1.08Mo0.92O8 were successfully grown from the MgVMo-Oxide flux, Mg2.54V1.08Mo0.92O8 crystallizes in the orthorhombic system, space group Pnma with a = 5.058(1) A , b = 10.307(3) A , c = 17.402(4) A , Z = 6 . The vanadium and molybdenum cations remain in their highest oxidation states and charge neutrality associated with the variation of the V Mo atomic ratio is balanced by an increase or decrease in the number of magnesium cations in the crystal.