Potassium hydrogen disilicate: A possible model compound for <sup>17</sup> O NMR spectra of hydrous silicate glasses
Bibliographic record
Abstract
Oxygen-17 magic angle spinning, non-spinning, 1 H-decoupled, 1 H- 17 O cross-polarization, and triple-quantum magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy experiments were performed at two different magnetic fields on crystalline potassium hydrogen disilicate (KHSi 2 O 5 ) and hydrous and anhydrous potassium tetrasilicate (K 2 Si 4 O 9 ), sanidine (KAlSi 3 O 8 ), and haplogranite (KAlSi 3 O 8 -NaAlSi 3 O 8 -SiO 2 ) glasses. Crystalline KHSi 2 O 5 has two bridging oxygen sites and one non-bridging oxygen site, and the NMR parameters for these two types of sites have been determined. The non-bridging oxygen (silanol) site is well-resolved and observed in a crystalline compound with an isotropic chemical shift (δ iso ) of 60 ppm, a quadrupolar coupling constant (C Q ) of 3.5 MHz, and an asymmetry parameter (η) of 0.35. Knowledge of the non-bridging-oxygen site parameters allows for comparisons to glassy or other materials that might have silanol-type structures. A similar peak can be found in the hydrous potassium silicate spectrum but not in the hydrous potassium aluminosilicate glass spectrum.
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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".