Total X-ray scattering and big-box modeling of pressure-induced local disorder and partial amorphization in CsPbBr<sub>3</sub>.

Celeste, Anna; Girdzis, Samuel P; Cladek, Bernadette R; Deschene, Christina R; Wolf, Nathan R; Chapman, Karena W; Karunadasa, Hemamala I; Tucker, Matthew G et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

The mechanisms governing pressure-induced amorphization and its reversibility in halide perovskites are not yet fully understood, particularly the contribution of local disorder. We performed high-pressure synchrotron total X-ray scattering and reverse Monte Carlo (RMC) big-box modeling using CsPbBr<sub>3</sub> as a model system to investigate short-range structural evolution in both the ordered and partially amorphous phases. While diffraction data indicate that long-range order persists up to 2 GPa, pair distribution function (PDF) analysis reveals significant local distortions, including PbBr<sub>6</sub> octahedral tilting and Cs displacement, which influence the bandgap through a complex interplay between bond compression and angular tilting. Beyond 2 GPa, CsPbBr<sub>3</sub> undergoes partial amorphization, with significant disordering of Cs and Br, while the Pb sublattice remains preserved, allowing for structural recovery upon decompression. Our work, accounting for both short- and long-range structural evolution through RMC modeling, successfully captures how disorder shapes the structural response of halide perovskites under pressure.