High-temperature phase transition and switchable dielectric properties of the [2-amino-3-methylpyridine]2[ZnBr4] complex

Abstract

Phase-transition materials are substances that can switch between structural states while releasing or absorbing latent heat. They often exhibit multifunctional properties such as dielectricity, piezoelectricity, pyroelectricity, ferroelasticity and ferroelectricity. These characteristics make them optimal green candidates for designing and fabricating energy storage modules, non-volatile memory devices, capacitors, sensors, and related applications. In this work, a high-temperature phase-transition complex, [2-amino-3-methylpyridine]₂[ZnBr₄] (1), with a zero-dimensional structure was successfully constructed, and it was subjected to TGA, DSC, X-ray single-crystal diffraction, dielectric characterization and analysis. These data indicated that the compound crystallized in the space group P at 293 K and exhibited excellent stability up to 450 K. A pair of endothermic and exothermic peaks was observed near 378 K and 432 K, demonstrating high reversibility. In the vicinity of the corresponding phase-transition temperature, 1 showed an obvious step-like dielectric platform reversible change. A strong association was found between these fascinating physical properties and the hydrogen bonds connecting various ionic units, complex units, and other structural features. The ability to construct organic–inorganic hybrid crystal materials achieved in this work is expected to yield dielectric switch materials with high phase transition and provide ideas for new high-tech materials.