Pyrochlores. XI. High-pressure studies of the antimonates A2Sb2O7 (A = Ca, Sr, Cd) and preparation of the weberite Sr2Bi2O7

Abstract

Reactive hot-pressing experiments at 60–70 kbar and 700–900 °C indicate that the relative stability of the pyrochlore and weberite phases of the A2Sb2O7 (A = Ca, Sr, Cd) antimonates depends primarily on the effective size of A2+ and the covalency of the A—O bond working in conjunction. The analogous bismuthate(V) Sr2Bi2O7, obtained by hot pressing of SrBiO3−x with an excess of KClO3, has been shown to have the weberite-type structure.