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 gained greater attention for potential applications. By consciously introducing a dynamic and spherical organic cation, RM3HQ (the R-N-methyl-3-hydroxylquinuclidinium cation), we synthesized a three-dimensional (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 that 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 support dielectric transitions, making 1 a type of switchable dielectric material. More importantly, the symmetry breaking at 410 K shows a ferroelastoelectric transition with the Aizu notation of 622F2. This study constructs a high-performance hybrid rare-earth perovskite and provides highly promising candidate materials for next-generation multifunctional electronic devices.