A prominent dielectric material with extremely high-temperature and reversible phase transition in the high thermally stable perovskite-like architecture

Abstract

A perovskite-like dielectric material, (C₃N₂H₅)·[Mn(HCOO)₃] (1), exhibiting remarkably high T_c (phase transition temperature) and pronounced dielectric anomaly, can be considered as a model of novel extremely high-temperature dielectric materials. The systematic characterizations, including detailed differential scanning calorimetry (DSC), variable-temperature single crystal X-ray and X-ray powder diffraction analyses, variable-temperature IR spectra as well as temperature-dependence and frequency-dependence dielectric measurements, reveal a sharp structural phase transition from tetragonal P2₁m at the HTP (high temperature phase) to monoclinic P2₁/c at the RTP (room temperature phase) and the mechanism of dielectric and thermal anomalies can be ascribed to the host–guest interaction coupled with the order–disorder transitions of the Mn(HCOO)₃⁻ cage and the [(C₃N₂H₅)]⁺ guest, which is the result of a synergistic effect. Emphatically, the T_c (438 K) is the highest reported so far for a molecule-based dielectric material (the T_c is below room temperature for the most known formate series perovskite-like dielectrics), which makes 1 a promising candidate for molecule-based dramatically high-temperature dielectric materials and may open up new possibilities to make a large breakthrough in the potential practical applications in sensing, dielectric devices, energy storage, data storage and molecular or flexible multifunctional electronic devices.