Above room-temperature dielectric switching in a new Zn-halide hybrid crystal based on pyrrolidine-derivative

Abstract

A new Zn-halide hybrid crystal based on pyrrolidine-derivative exhibits reversible phase transition at around 330 K/320 K (heating/cooling). • (HNBNMP) 2 (ZnCl 4 ) (HNBNMP = N-bromomethyl-N-methylpyrrolidinium cation, compound 1 ), shows a reversible phase transition at 330/320 K (heating/cooling) through differential scanning calorimetry (DSC). • Variable-temperature single-crystal structural analysis and powder X-ray diffraction patterns verify the structural phase transition. • Variable-temperature dielectric measurements show the dielectric switching behavior indicating the potential application in the dielectric functional materials. We have successfully synthesized compound 1 (HNBNMP) 2 (ZnCl 4 ) (HNBNMP = N-bromomethyl-N-methylpyrrolidinium cation) through the slow evaporation method at room temperature. Several studies (differential scanning calorimetry measurements, single crystal structural analysis, variable-temperature powder X-ray diffraction and dielectric measurements) show that compound 1 has a reversible structural phase transition at around 330 K/320 K (heating/cooling), respectively. Variable-temperature powder X-ray diffraction patterns further demonstrate that compound 1 undergoes a phase transition. Meanwhile, the unique phase transition behavior was also confirmed by its remarkable dielectric and thermal anomalies around the phase transition point. The step-like dielectric switching in compound 1 can be mainly ascribed to the motional changes of polar components between room-temperature and high-temperature phases. This finding should stimulate further synthesis for switchable functional materials.