Homogeneity area of MoO 3 solid solution in SbVO 5 in air

Abstract

DTA, XRD and XPS methods used to examine the V 2O 5 MoO 3 α-Sb 2O 4 system have shown that a substitution solid solution of MoO 3 in SbVO 5 is formed. Monophase samples of V/Sb/Mo mixed oxides of general formula Sb 1 − 5 y − q ( y + z ) □ q ( y + z ) V 1 − 5 z − p ( y + z ) □ p ( y + z ) Mo 5 ( y + z ) O 5 for y + z ∈ ( 0 – 0.0208 ) , were q + p = 1 , have been prepared by solid-state reaction in air at temperatures not exceeding 645 °C. A study of theoretically possible solid solution models has pointed to the fact that Mo 6+ ions are incorporated in the SbVO 5 crystal lattice instead of Sb 5+ and/or V 5+ ions and the compensation of redundant positive charges takes place through cation vacancies arising in the Sb 5+ and/or V 5+ sub-lattice. The solubility limit for MoO 3 in SbVO 5 does not exceed 20.00 mol%. The solution matrix, i.e., SbVO 5 crystallises in the monoclinic system and parameters of its unit cell have been calculated. XPS spectra of all monophase samples have shown that in the investigated solid solutions of MoO 3 in SbVO 5 vanadium, antimony and molybdenum occur mainly as V 5+, Sb 5+, Mo 6+.