High-Temperature Biferroicity in a Chiral 3D Hybrid Rare-Earth-Based Double Perovskite

Abstract

Recently, switchable physical properties have been discovered in functional hybrid rare-earth perovskites, which have raised greater attention for potential applications. By consciously introducing dynamical and spherical organic cation, RM3HQ (R-N-methyl-3-hydroxylquinuclidinium cation), we synthesized a threedimensional (3D) nitrate-bridged hybrid rare-earth perovskite, (RM3HQ)₄K₂[Nd(NO₃)₆]₂ (1), possessing a 4-connected LON framework with a 6⁶ topological network (Schläfli symbol). Thermal measurements show that 1 undergoes two reversible phase transitions, at around 370 K and 410 K, respectively. Various-temperature single-crystal structural analyses reveal 1 crystallizes in the polar space group P2₁ at 293 K and 390 K, respectively, and in the chiral space group P6₃22 at 428 K. The phase transitions arouse dielectric transitions, making 1 a type of switchable dielectric materials. More importantly, the symmetry breaking at 410 K shows a ferroelastoelectric transition with the Aizu notation of 622F2. This study not only constructs highperformance hybrid rare-earth perovskite but also provides highly promising candidate materials for nextgeneration multifunctional electronic devices.