Emergence of Tetragonal Phase and Reentrant Transition in Tensile-Strained Bi<sub>2</sub>(La<sub>1–<i>x</i></sub>Bi<sub><i>x</i></sub>)O<sub>4</sub>Cl Solid Solution
Bibliographic record
Abstract
Manipulating chemical bonding in a solid is crucial for controlling and realizing desirable properties. We have recently demonstrated that replacing the M 3+ cation of Bi 2 MO 4 Cl, which contains triple-fluorite slabs, from Y 3+ to a larger cation (La 3+, Bi 3+ ) induces tensile strain in the Bi–O square net, resulting in Bi–O bond cleavage to form double- and single-chain structures, respectively. In this study, we synthesized a solid solution of Bi 2 (La 1– x Bi x )O 4 Cl with almost uniform tensile strain, revealing an unexpected tetragonal (T) phase (0.15 ≤ x ≤ 0.35), along with an additional monoclinic single-chain phase (0.425 ≤ x ≤ 0.475). The emergence of the T phase with the elongated in-plane axis likely arises from the competition between the single and double chain structures. The T phase exhibits a narrower bandgap of 2.2 eV (vs Bi 2 YO 4 Cl), ascribed to the presence of Bi in the inner sublayer. Furthermore, the T phase undergoes a reentrant transition upon heating via the single-chain phase, forming a high-temperature tetragonal (T′) phase with partial Bi–O bond cleavage due to spatial and thermal fluctuations of the outer Bi cations. This study emphasizes the role of uniform tensile strain in promoting phase competition in triple fluorite layered systems, resulting in complex phase transitions under external stimuli. Controlling such delicate balance offers a pathway to engineering of physical properties of functional materials, such as visible-light photocatalysts.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".