Structural phenomena of metamict titanite: a synchrotron, X-ray diffraction and vibrational spectroscopic study
Bibliographic record
Abstract
Titanite, CaTiSiO5, occurs in nature in crystalline and metamict modification. Its structure consists of corner-linked TiO6 octahedra, SiO4 tetrahedra and sevenfold coordinated Ca. Metamictization occurs when a mineral contains impurities like U and Th and is exposed to radioactive irradiation. Recoil processes due to alpha radiation change over geological time scales the structure to a state with persisting short-range order but violated long-range order. Raman and infrared spectra and X-ray diffraction data of metamict as well as crystalline and titanite glass reveal local structural phenomena. Raman spectra of metamict titanite differ from spectra of well-crystalline titanite, indicating the breakdown of selection rules. Raman scattering reveals that anisotropy is preserved upon metamictization and that the structural state of highly metamict titanite should not be considered as quasi-amorphous. The metamict state partially recovers its disorder via heat treatment. Annealing-induced shrinking of unit cell volume is related to stiffening and improved local symmetry of SiO4 tetrahedra.
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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".