Preparation and properties of alkali metal chromium oxides of the formula MCr₃O₈

Abstract

Alkali metal chromium oxides of the formula MCr³O⁸ can be prepared by thermal decomposition of chlorochromates, trichromates and tetrachromates and by heating chlorochromates or alkali halides with chromium(V1) oxide. The preparation of lithium chlorochromate, LiCrO₃Cl, is described and new metastable phases of RbCr₂O₈ and CsCr₃O₈ are reported. The temperatures, products and enthalpies of decomposition for LiCr₃O₈, KCr₃O₈, RbCr₃O₈ and two forms of CsCr₃O₈ have been determined. The decomposition is modified in the presence of alkali halides.