Crystal structure of novel high-pressure perovskite K <sub>2/3</sub> Th <sub>1/3</sub> TiO <sub>3</sub> , a possible host for Th in the upper mantle
Bibliographic record
Abstract
The high-pressure perovskite K2/3Th1/3TiO3 was synthesized at P = 6 GPa and T = 1200 °C. This compound does not form at ambient pressures, as both solid-state reaction and synthesis from the melt yield a mixture of thorianite (ThO2) and jeppeite (K2Ti6O13). K2/3Th1/3TiO3 is a partially ordered derivative of the ideal perovskite structure, which crystallizes with tetragonal symmetry, in space group P4/mmm, a = 3.9007(2), c = 7.8099(7) Å, V = 118.83(2) Å3, Z = 2. The structure of this compound was refined by the Rietveld method from the X-ray diffraction powder data. The degree of disorder calculated from the refined cation occupancies of the 1a and 1b sites is 58%. The K1+ cations preferentially enter the 1a site, whereas most Th4+ is accommodated in the comparatively smaller 1b site (polyhedral volumes are 53 and 46 Å3, respectively). In response to this two-dimensional (planar) ordering, the Ti4+ cations are displaced by about 0.1 Å toward the planes populated by the lower-charged cations. K2/3Th1/3TiO3 and related structures may be a viable repository for Th in Ti-rich alkali metasomatites in the lithospheric upper mantle.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".