Pressure-induced Jahn-Teller switch in the homoleptic hybrid perovskite [(CH₃)₂NH₂]Cu(HCOO)₃: orbital reordering by unconventional degrees of freedom.

ABSTRACT: Through in situ, high-pressure X-ray diffraction experiments we have shown that the homoleptic perovskite-like coordination polymer [(CH₃)₂NH₂]Cu(HCOO)₃ undergoes a pressure-induced orbital reordering phase transition above 5.20 GPa. This transition is distinct from previously reported Jahn-Teller switching in coordination polymers, which required at least two different ligands that crystallize in a reverse spectrochemical series. We show that the orbital reordering phase transition in [(CH₃)₂NH₂]Cu(HCOO)₃ is instead primarily driven by unconventional octahedral tilts and shifts in the framework, and/or a reconfiguration of A-site cation ordering. These structural instabilities are unique to the coordination polymer perovskites, and may form the basis for undiscovered orbital reorientation phenomena in this broad family of materials.

SUBMITTER: Scatena R 

PROVIDER: S-EPMC8246535 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature