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

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.众所周知，通式为ABX₃（其中A、B为阳离子，X为阴离子）的钙钛矿（Perovskite）在过去半个世纪中得到了广泛研究，这得益于其多样的功能特性：例如钛酸钡（BaTiO₃）中的铁电性、锆钛酸铅（PZT，Lead Zirconate Titanate）中的压电性，以及近年在甲胺铅碘（CH₃NH₃PbI₃）中展现出的光伏特性。然而，其“反向”类似物——反钙钛矿（Antiperovskite，通式为X₃BA，其中A、B为阴离子，X为阳离子）却较少受到关注。尽管绝大多数重要的铁电材料均为钙钛矿，但自1930年反钙钛矿被发现以来，尚未有反钙钛矿铁电材料被报道。在此，我们首次报道了一种X₃BA型反钙钛矿铁电材料[(CH₃)₃NH]₃(MnBr₃)(MnBr₄)（其中(CH₃)₃NH为X，MnBr₃为B，MnBr₄为A），该材料展现出优异的铁电性，其相变温度高达458 K，同时还具备引人入胜的光致发光特性，拥有两处强发射峰。这一发现为探索高性能功能材料领域的反钙钛矿黄金研究方向开辟了全新路径。