Low‐energy Sr<sub>2</sub><scp>MSbO<sub>5.5</sub></scp> (M = Ca and Sr) structures show significant distortions near oxygen vacancies
Bibliographic record
Abstract
Abstract Inspired by significant local distortions found near vacancies in a neutron pair distribution function analysis study (G. King et al., Inorg. Chem. 2012, 51, 13060) of Sr2MSbO5.5 (M = Ca and Sr), this computational study finds minimum‐energy structures with these and related distortions using density functional theory (DFT) with the Perdew‐Burke‐Ernzerhof (PBE) functional as implemented in the Vienna Ab Initio Simulations Package (VASP) (G. Kresse and J. Furthmüller, Phys. Rev. B, 1996, 54, 11169; G. Kresse and J. Hafner, Phys. Rev. B, 1993, 47, 558; G. Kresse and J. Furthmüller, Comput. Mater. Sci., 1996, 6, 15). All structures were optimized using the conjugate gradient method. The global minima found for both systems featured trigonal bipyramid SbO5 structures and edge sharing with M‐centered polyhedra. However, while calcium ions occupied full and partial octahedra, the larger strontium ions were more commonly found in full and partial pentagonal bipyramids. Molecular dynamics with velocity rescaling at 1200 K revealed movements of the oxygen vacancy via polyhedral rotations. This work highlights the need to consider both square pyramid to trigonal bipyramid rearrangements around small ions and rotational polyhedral movements in simulating oxygen vacancy conduction in oxygen‐deficient double perovskites.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.001 | 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) | 0.003 | 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 source (direct Gemma or distilled Codex), 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".