NMR Crystallography of Monovalent Cations in Inorganic Matrices: Na<sup>+</sup> Siting and the Local Structure of Na<sup>+</sup> Sites in Ferrierites
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Zeolites are crystalline microporous aluminosilicates of paramount importance. The siting of cations balancing the negative charge of framework Al affects the catalytic and sorption properties of cation-exchanged zeolites. The siting of Na + cations in dehydrated Si-rich ferrierite zeolites is investigated by 23 Na (ultra)-high-field (MQ)MAS NMR spectroscopy together with DFT to obtain the Na + siting and the local structure of nine Na + cationic sites formed by two 6-rings and two 8-rings having one Al atom located in different framework T sites. The occupation of the Na + cationic sites is not controlled by their relative energies but by the kinetics of the Na + ion-exchange. 23 Na solid-state NMR spectroscopy alone can determine the ring forming the Na + site but not which T site is occupied by Al in that ring. The developed methodology represents a highly promising tool for the analysis of the Na + arrangements in zeolites and other crystalline matrices.
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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) | 0.002 | 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".