Structural Stability and Phase Transitions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi mathvariant="normal">K</mml:mi><mml:mn>8</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mi mathvariant="normal">S</mml:mi><mml:mi mathvariant="normal">i</mml:mi></mml:mrow><mml:mn>46</mml:mn></mml:msub></mml:math>Clathrate under High Pressure
Bibliographic record
Abstract
The structural stability of type-I ${\mathrm{K}}_{8}{\mathrm{S}\mathrm{i}}_{46}$ clathrate has been investigated at high pressure by synchrotron x-ray diffraction. In contrast to that observed in the Na-doped structure-II analogue [A. San-Miguel et al., Phys. Rev. Lett. 83, 5290 (1999)], no phase separation into the $\ensuremath{\beta}\mathrm{\text{\ensuremath{-}}}\mathrm{S}\mathrm{n}$ Si structure was identified at 11 GPa. Instead, ${\mathrm{K}}_{8}{\mathrm{S}\mathrm{i}}_{46}$ is found to undergo a transition to an isostructural positional disordered phase at around 15 GPa. Ab initio phonon band structure calculations reveal a novel phenomenon of phonon instabilities of K atoms in the large cavities is responsible for this transition. Above 32 GPa, the new structure transforms into an amorphous phase.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 0.001 |
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".