Thermal evolution of phosphates and sulfates witn an antiperovskite-type structure: thermal expansion and phase transitions

In this study, we present an investigation of the thermal behavior of natural and synthetic phosphates and sulfates with an antiperovskite-type structure, where the anion-centered octahedron is the main structural unit. We discuss examples of the thermal behavior of antiperovskites with classical and hexagonal 3D frameworks (K3SO4F, Rb3SO4F, synthetic analogue of kogarkoite Na3SO4F, galeite Na15(SO4)5ClF4, schairerite Na21(SO4)7ClF6); with one-dimensional (1D) chains of corner- and face-sharing octahedra (nacaphite Na2CaPO4F and its synthetic dimorph, synthetic analogue of moraskoite Na2CaPO4F, nefedovite Na5Ca4(PO4)4F); and with clusters represented by trimers of anion-centered octahedra (synthetic analogue of arctite (Na5Ca)Ca6Ba(PO4)6F3). Based on the obtained data, some general patterns were identified, depending on the structural topology and thermal stability of antiperovskites.