Coexistence of A‐ and B‐Site Vacancy Compensation in La‐Doped Sr <sub> 1− <i>x</i> </sub> Ba <i> <sub>x</sub> </i> TiO <sub>3</sub>
Bibliographic record
Abstract
BaTiO 3 and SrTiO 3 perovskites of the A 2+ B 4+ O 3 type form complete solid solution, Sr 1− x Ba x TiO 3 , which can accommodate a substantial amount of donor dopants, for example, La. At high oxygen partial pressure, La dopants in SrTiO 3 are compensated by A‐site vacancies, whereas in BaTiO 3 they are compensated by B‐site vacancies. Therefore, donor compensation in the Sr 1− x Ba x TiO 3 solid solution should demonstrate a crossover from the A‐site vacancies at x =0 to the B‐site vacancies at x =1. One may expect, therefore, that at some critical concentration, x c , the free energy of the Sr 1− x Ba x TiO 3 system can become invariant to the vacancy compensation regime. In other words, the system will adopt either A‐ or B‐site vacancies depending on the target chemical composition. Based on the Rietveld refinement of X‐ray diffraction patterns and their phase composition analysis as well as scanning electron microscopic and transmission electron microscopic data, we demonstrate that the 28% La‐doped Sr 1− x Ba x TiO 3 system equilibrated at 1400°C indeed becomes invariant to the vacancy‐type compensation at x c ≈0.25 and can accommodate A‐ and B‐site vacancies at any given ratio. Finally, we propose a microscopic model based on the off‐center Ti displacement and the partial covalency of Ti–O bond to explain the distinct difference in the vacancy compensation mechanisms in BaTiO 3 and SrTiO 3 . These findings are important for a further understanding of the thermodynamics of the intrinsic point defects in perovskites as well as for the improvement of electrical performance of the solid oxide fuel cells, ferroelectric, and voltage‐tunable ceramics.
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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 | 0.000 | 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) | 0.001 | 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".