Homogeneity area of MoO3 solid solution in SbVO5 in air

DTA, XRD and XPS methods used to examine the V2O5MoO3α-Sb2O4 system have shown that a substitution solid solution of MoO3 in SbVO5 is formed. Monophase samples of V/Sb/Mo mixed oxides of general formula Sb1−5y−q(y+z)□q(y+z)V1−5z−p(y+z)□p(y+z)Mo5(y+z)Sb1−5y−q(y+z)□q(y+z)V1−5z−p(y+z)□p(y+z)Mo5(y+z)O5 for y+z∈(0–0.0208)y+z∈(0–0.0208), were q+p=1q+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 Mo6+ ions are incorporated in the SbVO5 crystal lattice instead of Sb5+ and/or V5+ ions and the compensation of redundant positive charges takes place through cation vacancies arising in the Sb5+ and/or V5+ sub-lattice. The solubility limit for MoO3 in SbVO5 does not exceed 20.00 mol%. The solution matrix, i.e., SbVO5 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 MoO3 in SbVO5 vanadium, antimony and molybdenum occur mainly as V5+, Sb5+, Mo6+.

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