Garnet-type Na3Te2(FeO4)3

Abstract

Na₃Te₂(FeO₄)₃ or Na₃Te₂Fe₃O₁₂, tris-odium ditellurium(VI) triiron(III) dodeca-oxide, was obtained in the form of single-crystals under hydro-thermal conditions. Na₃Te₂(FeO₄)₃ adopts the garnet structure type in space group Ia d and comprises one Na (multiplicity 24, Wyckoff letter c, site symmetry 2.22), one Te (16 a, ..), one Fe (24 d, ..) and one O atom (96 h, 1) in the asymmetric unit. The three-dimensional framework structure is built of [TeO₆] octa-hedra and [FeO₄] tetra-hedra by vertex-sharing. The larger Na⁺ cations are situated in the inter-stices of the framework and are eightfold coordinated in the form of a distorted dodeca-hedron. Qu-anti-tative structural comparisons with isotypic Na₃Te₂[(Fe_0.5Al_0.5)O₄]₃ and Na₃Te₂(GaO₄)₃ show a high degree of similarity between the three crystal structures.

Keywords: crystal structure; garnet; isotypism; oxidotellurate(VI); structural similarity.