Phase relations in the MgMoO4-Mg3V2O8 system and crystal structure of Mg2.54V1.08Mo0.92O8

Article abstract of DOI:10.1016/S0925-8388(96)02381-X

The phase relationships in the pseudobinary MgMoO₄-Mg₃V₂O₈ system have been determined by differential thermal analysis and X-ray diffraction analysis. The intermediate compound Mg_2.5VMoO₈ was found to exhibit a considerable solid solution Mg_2.5+xV_1+2xMo_1-2xO₈ (- 0.05 ≤ x ≤ 0.05) at 1100°C in air. Single crystals with composition of Mg_2.54V_1.08Mo_0.92O₈ were successfully grown from the Mg-V-Mo-Oxide flux. Mg_2.54V_1.08Mo_0.92O₈ crystallizes in the orthorhombic system, space group Pnma with a = 5.058(1) angstrom, b = 10.307(3) angstrom, c = 17.402(4) angstrom, 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.