Phases of anionic ordering in elpasolite structures (Ordered perovskites)

Abstract

The 108 dissymmetric phases were obtained as a result of X anions ordering in elpasolite structure A2BB′X6 (ordered perovskite) using group theoretical methods. The critical order parameters which transform according to the irreducible representations of Γ and X points of Brillouin zone of O5h— F m3m space group were considered only. Polyhedral structures showed for dissymmetric phases which are ac- companied by appearing of ferroelectricity at phase transition. All results are summarized in convenient tables.