Coexistence of tilting and antitilting in cubic perovskites

This paper is devoted to the calculation of diffuse scattering and its temp erature evolution in some cubic perovskites with three structural phase tra nsitions which are associated with octahedra rotations, The model of atom v ibrations in a three-well potential makes it possible to describe simultane ous existence of both tilting and antitilting superstructure reflections at intermediate temperatures. The theoretical predictions are in good agreeme nt with the temperature behaviour of superstructure reflections observed in scattering experiments on RbCaF3, CsPbBr3, CsPbCl3.