High-temperature structural phase transition coupled with dielectric switching in an organic-inorganic hybrid crystal: [NH(CH)Br]CdBr.

Molecular bistable switches (electrical switches "ON" and "OFF") represent a class of highly desirable intelligent materials due to their sensitive switchable responses, simple and environmentally friendly processing, light weight, and mechanical flexibility. In particular, these switches above room temperature with potential practical application are rarely reported. In this work, a new zigzag chained organic-inorganic hybrid compound [NH(CH)Br]CdBr (1), which displays rapidly sensitive dielectric switching reversibility and remarkable switching antifatigue, has been successfully synthesized. Systematic characterization including differential scanning calorimetry measurements (DSC), dielectric measurements, and variable-temperature structural analyses was performed to reveal the phase transition of 1. A couple of reversible heat anomaly peaks at 335.6/323.8 K with a large hysteresis (ca. 11.8 K) were observed in the DSC curve, indicating the first-order type of phase transition. 1 exhibits an obvious dielectric switching at around 327 K, which makes 1 a potential switchable dielectric material. Variable-temperature structural analyses show that the cationic order-disorder motion is the main attribution for the phase transition of 1.