alpha-ScVSe2O8, beta-ScVSe2O8, and ScVTe2O8: New Quaternary Mixed Metal Oxides Composed of Only Second-Order Jahn-Teller Distortive Cations

Abstract

Three new quaternary scandium vanadium selenium/tellurium oxides, alpha-ScVSe2O8, beta-ScVSe2O8, and ScVTe2O8 have been synthesized through hydrothermal and standard solid-state reactions. Although all three reported materials are stoichiometrically similar, they exhibit different crystal structures: alpha-ScVSe2O8 has a three-dimensional framework structure consisting of ScO6, VO6, and SeO3 groups. beta-ScVSe2O8 reveals another three-dimensional framework composed of ScO7, VO5, and SeO3 polyhedra. ScVTe2O8 shows a layered structure with ScO6, VO4, and TeO4 polyhedra. Interestingly, the constituent cations, that is, Sc3+, V5+, Se4+, and Te4+ are all in a distorted coordination environment attributable to second-order Jahn-Teller (SOJT) effects. Complete characterizations including infrared spectroscopy, elemental analyses, thermal analyses, dipole moment calculation, and the magnitudes of out-of-center distortions for the compounds are reported. Transformation reactions suggest that alpha-ScVSe2O8 may change to beta-ScVSe2O8, and then to Sc-2(SeO3)(3)center dot H2O under hydrothermal conditions.