Ferroelastic Domains and Effects of Spontaneous Strain in Lead Halide Perovskite CsPbBr<sub>3</sub>
Bibliographic record
Abstract
Halide perovskites have shown great promise for applications in solar cells and other optoelectronic devices. It was recently realized that lattice strain can be considered an effective parameter for the performance of these materials due to their mechanical softness. Various strain-engineering strategies have been considered involving external and internal strains; the latter arises from size mismatch between the cations and halide cage and from crystal defects. Here, we demonstrate the importance of another type of internal strain, namely, a temperature-dependent spontaneous strain originating from ferroelastic phase transitions often observed in halide perovskites. We investigate CsPbBr 3 single crystals in the temperature range between 80 and 500 K using polarized light microscopy, X-ray diffraction, and measurements of dielectric properties. This material has excellent optoelectronic performance, but several controversial results related to its crystal structure, phase transitions, and ferroelectricity have been reported. Studies of twin domain structures, birefringence, and permittivity allow us to accurately deduce the phase symmetries and confirm the existence of two phase transitions: between orthorhombic and tetragonal phases at 361 K and between tetragonal and cubic phases at 403 K. The domain response under an external electric field or stress reveals that this crystal is not ferroelectric or antiferroelectric but ferroelastic. We show that the anomalies of some properties previously related to additional phase transitions can be interpreted as artifacts caused by changes in the ferroelastic domain structure and the related inhomogeneous internal strain. This work provides a better understanding of the structure–property relations in ferroelastic halide perovskites.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".