Anomalous and colossal thermal expansion, photoluminescence, and dielectric properties in lead halide-layered perovskites with cyclohexylammonium and cyclopentylammonium cations.

ABSTRACT: A detailed study of lead halide-layered perovskites with general formula A₂PbX₄ (where A is cyclohexylammonium (CHA) or cyclopentylammonium (CPA) cation and X is Cl^- or Br^- anion) is presented. Using variable temperature synchrotron X-ray powder diffraction, we observe that these compounds exhibit diverse crystal structures above room temperature. Very interestingly, we report some unconventional thermomechanical responses such as uniaxial negative thermal expansion and colossal positive thermal expansion in a perpendicular direction. For the polymorphs of (CHA)₂PbBr₄, the volumetric thermal expansion coefficient is among the highest reported for any extended inorganic crystalline solid, reaching 480 MK^-1. The pha

SUBMITTER: Cuquejo-Cid A 

PROVIDER: S-EPMC9167970 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature