Electronic structure and stability of hexagonal<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>Ba</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mtext>Ti</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mtext>RuO</mml:mtext></mml:mrow><mml:mn>9</mml:mn></mml:msub></mml:mrow></mml:math>
Bibliographic record
Abstract
We investigated the electronic structure and stability of the hexagonal perovskite ${\text{Ba}}_{3}{\text{Ti}}_{2}{\text{RuO}}_{9}$ using high-resolution electron energy loss spectroscopy and first-principles band structure calculations. The comparison between experimental and theoretical results leads to a coherent picture of the electronic structure of this compound where both Ti and Ru ions are tetravalent, the first unoccupied states being of $\text{Ru}\text{ }4d$ character. Structural relaxations performed on four variants of this compound allowed a detailed investigation of the influence of the Ru atoms location in the hexagonal unit cell and clarified the origin of the stabilization of this phase at room temperature. Two structures without inversion symmetry built, respectively, with two ${\text{TiRuO}}_{9}$ units (space group $\text{P}{6}_{3}\text{mc}$, 186) or with one ${\text{Ru}}_{2}{\text{O}}_{9}$ and one ${\text{Ti}}_{2}{\text{O}}_{9}$ unit $(\text{P}\overline{6}\text{m}2,187)$ are found to be the most stable. The stabilization of the first structure occurs through the polarization of the partially filled $\text{Ru}\text{ }4d$ bands, whereas a direct metal-metal bonding interaction taking place between the two Ru atoms in the ${\text{Ru}}_{2}{\text{O}}_{9}$ unit lowers the total energy of the second. The influence of the exchange correlation functional used to perform these calculations on the relative stability of the four variants is discussed.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".