Discovery of an Antiperovskite Ferroelectric in [(CH₃)₃NH]₃(MnBr₃)(MnBr₄)

Abstract

It is known that perovskites with the general chemical formula of ABX₃ (A, B = cations, X = anion) have been intensively studied over the last half century because of their diverse functional properties, such as ferroelectricity in BaTiO₃, piezoelectricity in PZT (lead zirconate titanate), and recently developed photovoltaic properties in CH₃NH₃PbI₃. However, rather less attention has been paid to their "inverse" analogs, antiperovskites, which have a chemical formula X₃BA, where A and B are anions and X is a cation. Although most of important ferroelectrics are perovskites, no antiperovskite ferroelectrics have been found since the discovery of antiperovskites in 1930. Here, for the first time, we report a X₃BA antiperovskite ferroelectric [(CH₃)₃NH]₃(MnBr₃)(MnBr₄) (where (CH₃)₃NH is X, MnBr₃ is B, and MnBr₄ is A), which shows outstanding ferroelectricity with a significantly high phase transition temperature of 458 K as well as fascinating photoluminescence properties with two intense emissions. This finding opens a new avenue to explore the golden area of antiperovskites for high-performance functional materials.