Cooperative Effects of Cation Size and Variable Coordination Modes of Te4+ on the Frameworks of New Alkali Metal Indium Tellurites, NaIn(TeO3)(2), KIn(TeO3)(2), RbInTe3O8, and CsInTe3O8

Abstract

Four new alkali metal indium tellurites, NaIn(TeO3)(2), KIn(TeO3)(2), RbInTe3O8, and CsInTe3O8, have been prepared through hydrothermal and solid state synthesis reactions using corresponding alkali metal carbonates, In2O3 [or In(NO3)(3)center dot xH(2)O], and TeO2. The structures of the reported materials have been determined by powder and single crystal X-ray diffraction. The mixed indium tellurites reveal a rich structural chemistry with different channel structures. NaIn(TeO3)(2) shows 8-membered rings, whereas stoichiometrically similar KIn(TeO3)(2) exhibits both 8- and 12-membered rings in the frameworks. Isostructural RbInTe3O8 and CsInTe3O8 reveal three-dimensional frameworks consisting of InO6, TeO3, and TeO4 groups. Close structural examination suggests that the alkali metal cation size and variable coordination modes of Te4+ cations cooperatively influence the framework geometries of the new mixed metal tellurites. Detailed characterizations including spectroscopic, elemental, and thermal analyses are introduced. Local dipole moments and out-of-center distortions for the constituent polyhedra are also reported.