The structures of strontium tellurite and strontium telluride aluminate sodalites studied by powder neutron diffraction, EXAFS, IR and MAS NMR spectroscopies

Abstract

Aluminate sodalites containing the telluride and tellurite ions have been synthesised for the first time. The structures of Sr₈[AlO₂]₁₂(TeO₃)₂ and its reduced product Sr[AlO₂]₁₂Te₂ have been determined using Rietveld refinement of powder neutron diffraction data. In Sr₈[AlO₂]₁₂Te₂ the anion occupies a position at the sodalite cage centre, whilst in Sr₈[AlO₂]₁₂(TeO₃)₂ the larger tellurite ion is displaced to allow reasonable coordination to the strontium ions. The reduction of the occluded (TeO₃)^2– to Te^2– has also been investigated using IR spectroscopy, ²⁷Al and ¹²⁵Te MAS NMR spectroscopies and Te L_III-edge EXAFS.