29Si AND 23Na MAS NMR SPECTROSCOPIC STUDY OF THE POLYTYPES OF THE TITANOSILICATE PENKVILKSITE
Bibliographic record
Abstract
Simulations of 29Si and 23Na MAS NMR spectra indicate the presence of differing proportions of two polytypes and a third phase in three samples of penkvilksite, Na4Ti2Si8O22•5H2O. The most abundant peaks are assigned to the 2O and 1M polytypes, and a third set of peaks are provisionally assigned to a proposed 2M polytype. The quadrupolar interaction parameters for 23Na, Cq and , were calculated using the full- crystal linearized augmented plane-wave model (FC LAPW) for the 1M and 2O polytypes. The values obtained for Cq from the simulations of 23Na spectra and from the LAPW calculations for the 1M polytype are close, 3.3 and 3.5 MHz, respectively. However, for the 2O polytype, these values are 3.3 and 1.5 MHz, indicating that the Rietveld refinement of the structure for the 2O polytype is not as accurate as the single-crystal refinement of the 1M polytype, from which the 2O structure was optimized to obtain a value of Cq closer to the measured one. The ratios of these polytypes for the three samples of penkvilksite, obtained independently from simulations of 29Si and 23Na spectra, agree within 9 % for the 1M and 2O polytypes.
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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) | 0.000 | 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) | 0.000 | 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".