Series of Cage-Like Double Perovskite-Type Hybrid Perovskites with Reversible Structural Phase Transition and Switchable Dielectric Constant Property

A series of cage-like double perovskite-type hybrid perovskites, (HQ)2[B′Bi(NO3)6] (HQ = quinuclidinium cation, B′ = K, 1; Rb, 2; Cs, 3), were obtained. In the cages, the Bi3+ ions are dodecahedrally coordinated by six NO3– ligands in a bidentate mode; meanwhile, each alkali metal ion is chelated by six O atoms from neighboring six NO3– ions. The HQ exists in the anionic cage through intermolecular interactions, which mainly refers to hydrogen-bonding interactions. They display structural phase transitions between 200 and 250 K. Various-temperature (VT) single structural analysis reveals that 1–3 possess similar phase transitions arising from the reorientation of the HQ and the drastic structure changes of the anionic framework. The structural phase transition in 1–3 also arouse striking dielectric transitions. Then, the tunable thermodynamic property, especially the switchable phase transition temperature, was verified by Hirshfeld surface analyses, which is mainly used to describe the changing of the interactions between the HQ and [B′Bi(NO3)6] framework of those compounds. It is found that the intermolecular interactions of 1–3 and the radius of the B′ ion have a linear relationship. This finding will be meaningful for exploring high-performance stimulus-responsive dielectrics in the electronics or electrical industry.