Solid-State <sup>87</sup>Sr NMR Spectroscopy at Natural Abundance and High Magnetic Field Strength
Bibliographic record
Abstract
Twenty-five strontium-containing solids were characterized via (87)Sr NMR spectroscopy at natural abundance and high magnetic field strength (B0 = 21.14 T). Strontium nuclear quadrupole coupling constants in these compounds are sensitive to the strontium site symmetry and range from 0 to 50.5 MHz. An experimental (87)Sr chemical shift scale is proposed, and available data indicate a chemical shift range of approximately 550 ppm, from -200 to +350 ppm relative to Sr(2+)(aq). In general, magnetic shielding increased with strontium coordination number. Experimentally measured chemical shift anisotropy is reported for stationary samples of solid powdered SrCl2·6H2O, SrBr2·6H2O, and SrCO3, with δaniso((87)Sr) values of +28, +26, and -65 ppm, respectively. NMR parameters were calculated using CASTEP, a gauge including projector augmented wave (GIPAW) DFT-based program, which addresses the periodic nature of solids using plane-wave basis sets. Calculated NMR parameters are in good agreement with those measured.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".