STRUCTURAL RELATIONSHIPS BETWEEN COMPOUNDS BASED ON THE STACKING OF MIXED LAYERS RELATED TO HEXAGONAL PEROVSKITE-TYPE STRUCTURES

Ever since the discovery of high-temperature superconductivity in layered copper oxides, interest in materials exhibiting two-dimensional crystal structures related to perovskites (AMX(3)) has greatly increased, This review deals with crystal structures of various phases derived from perovskite with mixed stacking of [AX(3)] and [A(n)X(m)] (n + m less than or equal to 4) layers. Based on their structural relationships with the perovskite-related hexagonal polytypes, the possibility of forming compounds adopting new structure types derived from mixed stacking of various layers will be discussed. In addition, this review will also highlight the similarities between the perovskite structure and the structures of phases as varied as vanadates, phosphates etc., in which part of the structure is made up of cations present in a tetrahedral environment.