Xiandong Wang

Crystal structure of Zn3.77V1.54Mo1.46O12 containing ZnO6 trigonal prisms

Abstract 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).

Phase relations in the MgMoO4Mg3V2O8 system and crystal structure of Mg2.54V1.08Mo0.92O8

Abstract 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.

Reduction of magnesium orthovanadate Mg3(VO4)2

Abstract 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.

Crystal growth, structure, and properties of manganese orthovanadate Mn3(VO4)2

Abstract Manganese orthovanadate Mn3(VO4)2 single crystals were grown for the first time from a flux of MnO/V2O5/MoO3. The flux and oxygen partial pressure used are the key factors for the crystal growth and prevention of the oxidation of Mn2+ and the reduction of V5+ during the crystallization process. The reduction and oxidation chemistry of Mn3(VO4)2 was studied. Mn3(VO4)2 is isostructural with magnesium orthovanadate Mg3(VO4)2, orthorhombic, space group Cmca, a=6.247(1) A, b=11.728(2) A, c=8.491(2) A and Z=4, as determined by single crystal X-ray diffraction. Because it is a Mn2+ deficient spinel structure there are two-dimensional sheets of Mn2+O6 octahedra within the structure which show unusual ferrimagnetic properties.

Crystal growth and structure of Mn2.47V0.94Mo1.06O8

Abstract 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.

Crystal growth and co-substitution in (Mg1-xFex)(Mo2-xVx)O7 (0.13≤x≤0.47) with (V/Mo)=O oxo double bonds

Abstract 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.