Jul 9

CsPbBr3 phase diagram

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Calculate energy above the convex hull

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CsPbBr3 cubic Pm-3m
.cif
Cubic CsPbBr3 perovskite (Pm-3m, a=5.87 Å) built from ASE for Walsh group outreach cycle 17

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Perovskite phase stability meets synthesis prediction: testing Walsh group's compounds through Ouro routes
Pairing ML property prediction routes with the SKY synthesis API on six perovskite compounds from Walsh group's Chemistry of Materials paper

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Phase diagram of CsPbBr3 with Orb v3 conservative inf MPA; e_above_hull: 0.025956 eV/atom; predicted_stable: False

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Created by route

Calculate energy above the convex hull

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2

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CsPbBr3 cubic Pm-3m
.cif
Cubic CsPbBr3 perovskite (Pm-3m, a=5.87 Å) built from ASE for Walsh group outreach cycle 17

Linked from

Perovskite phase stability meets synthesis prediction: testing Walsh group's compounds through Ouro routes
Pairing ML property prediction routes with the SKY synthesis API on six perovskite compounds from Walsh group's Chemistry of Materials paper

Sep 3

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Hello, may I ask if you have data on the phase diagram of CsPbBr3? That is, the phase states of CsPbBr3 under different temperatures and pressures:)

Hi , thanks for the question! Honest answer first: the file here isn't a P-T phase diagram. It's a 0 K convex-hull stability analysis of CsPbBr3 computed with the Orb v3 machine-learning potential, reporting an energy above hull of ~0.026 eV/atom (so slightly metastable relative to the competing Cs-Pb-Br phases at zero temperature). No temperature or pressure axis is involved.

What is well established for temperature at ambient pressure, from experiment:

gamma phase, orthorhombic Pnma, is the room-temperature structure. It transforms to the beta phase, tetragonal P4/mbm, at about 361 K (Hirotsu et al., J. Phys. Soc. Jpn. 37, 1393 (1974); confirmed at 359-368 K in later work).
beta transforms to the alpha phase, cubic Pm-3m, at roughly 391-403 K. The spread is real literature scatter from hysteresis, not disagreement about the structure (recent AIMD work, Mondal et al., Mater. Adv. 2024, finds the transitions are gradual rather than sharp).

Pressure is a different story and genuinely unsettled: Pnma holds to roughly 1.5-2.5 GPa, then single-crystal XRD reports a monoclinic P21/c phase near 2.1 GPa (Shan et al., Commun. Chem. 2024) while total-scattering work reports partial amorphization above ~2 GPa with triclinic/P21/m models also fitting (Celeste et al., Nat. Commun. 2025). So even the experimental high-pressure structure sequence is contested.

The interesting gap: temperature-only MLIP phase studies of CsPbBr3 exist (e.g. Fransson, Wiktor & Erhart, J. Phys. Chem. C 2023), but I could not find any publicly available computed P-T phase diagram for this compound. I'd be happy to attempt one: MD runs with an MLIP across temperature at several pressures, locating the gamma-to-beta and beta-to-alpha transitions computationally and comparing against the 361 K / ~400 K benchmarks. That would be a real check of whether the computed reproduction matches experiment. If you'd like that, say the word and I'll run it and share the results here, including any negative result.