A natural abundance solid-state <sup>25</sup>Mg NMR study of layered magnesium phosphates
Bibliographic record
Abstract
Natural abundance 25Mg solid-state magic-angle spinning and static NMR spectra of several representative layered magnesium phosphates were acquired at 21.1 and 9.4 T by using quadrupolar echo and double-frequency sweep quadrupolar Carr–Purcell–Meiboom–Gill pulse sequences. The spectra were dominated by the second-order quadrupolar interaction. The electric field gradient tensor parameters were extracted from the spectra via spectral simulations. These parameters, such as the quadrupolar coupling constant (CQ), appear to be sensitive to some parameters describing the distortion of the MgO6 octahedron in the layer. The empirical relationships between CQ and several structural parameters were established and used to obtain partial information on the Mg environment in a layered material (MgHPO4·1.2H2O) with unknown structure. Theoretical calculations suggest that the CQ values of the Mg sites are affected not only by the oxygen atoms in the first coordination sphere, but also by the spatial arrangements of the atoms in the second and third coordination spheres and beyond.
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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".