Hydrothermal Synthesis and Crystal Structure of AgVMO5 (M = Se, Te)

Abstract

AbstractSingle crystals of AgVSeO5 and AgVTeO5 were obtained under hydrothermal conditions at 190 °C by reacting stoichiometric amounts of AgNO3, NaVO3, TeO2 and SeO2, respectively. AgVSeO5 crystallizes in Pbcm with a = 418.14(3) pm, b = 2007.70(6) pm, c = 521.17(2) pm, V = 437.52(2) × 106 pm3 and Z = 4, as red needles. The structure consists of VO5 square pyramids, trigonal SeO3 pyramids and AgO8 polyhedra, as primary building units. The VO5 square pyramids are linked to chains running along the c‐axis, by sharing oxygen atoms in the basal plane in cis‐position. The remaining basal O atoms of the VO5 moieties are shared with two oxygen atoms of the SeO3 units. The resulting polyanionic strands of composition [VSeO5]− are interconnected by silver atoms to form a three dimensional network. AgVTeO5 crystallizes as yellow needles in P21/c with a = 586.59(1) pm, b = 1137.98(2) pm, c = 680.78(1) pm, β = 102.733(1)°, V = 443.26(1) × 106 pm3 and Z = 4. The structure consists of VO4 tetrahedra, Ψ‐trigonal‐bipyramidal TeO4 units and AgO8 polyhedra as primary building units. The TeO4 groups form dimers by edge sharing, which are linked through vertices to the VO4 tetrahedra. The resulting one dimensional polyanion is extending along [101]. The structural motifs and charge distribution according to Se4+/V5+, and Te4+/V5+ respectively, seem to allow for a reshuffling of the charge distribution, thus inducing interesting physical phenomena, at elevated temperatures or pressures.