Ultrahigh-Field <sup>25</sup>Mg NMR and DFT Study of Magnesium Borate Minerals
Bibliographic record
Abstract
A series of well-characterized magnesium borate minerals and synthetic analogues have been studied via ultrahigh-field 25 Mg solid-state NMR spectroscopy. Correlations between 25 Mg NMR parameters and the local structure at the magnesium site(s) are highlighted and discussed. First-principles density functional theory calculations of 25 Mg NMR parameters carried out with the WIEN2k software package support our experimental 25 Mg NMR data. Experimental 25 Mg C Q values range from 0.7 ± 0.1 MHz in hungchaoite to 18.0 ± 0.5 MHz in boracite-type Mg 3 B 7 O 13 Br. To our knowledge, the latter C Q value is the largest reported 25 Mg nuclear quadrupole coupling constant. In general, C Q values correlate positively with the degree of geometrical distortion at the Mg site, despite the diversity in nearest-neighbor ligands (O 2–, OH –, H 2 O, F –, Cl –, and Br – ) across the series of magnesium borates. Experimental δ iso values range from 0.2 ± 0.5 ppm in hungchaoite to 23 ± 3 ppm in grandidierite, which are within the expected chemical shift range for diamagnetic magnesium borates.
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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".