Design and Prominent Dielectric Properties of a Layered Phase-Transition Crystal: (Cyclohexylmethylammonium)₂CdCl₄

Abstract

Following our recent finding of interesting dielectric and ferroelectric properties in semiconducting organic–inorganic layered perovskites (benzylammonium) 2 PbCl 4 and (cyclohexylammonium) 2 PbBr 4–4 x I 4 x ( x = 0–1), we designed a new layered perovskite-type crystal (cyclohexylmethylammonium) 2 CdCl 4 . By systematic characterizations, including differential scanning calorimetry measurements, dielectric measurements, and variable-temperature structural analysis, this crystal was found to undergo a reversible first-order phase transition at around T c = 342 K. The origin of the phase transition is associated with the order–disorder change of the organic cation as expected. The phase transition is accompanied by the anticipated large dielectric constant change and remarkable dielectric anisotropy. These dielectric performances reveal potential application of the crystal as a high-temperature dielectric material. More interesting dielectric crystals are expected to be tailored in the future by taking advantage of the richness of layered perovskites.