CHAINS OF EDGE-SHARING OPb4 TETRAHEDRA IN THE STRUCTURE OF Pb4O(VO4)2 AND IN RELATED MINERALS AND INORGANIC COMPOUNDS
Bibliographic record
Abstract
Nous avons resolu la structure cristalline du compose Pb 4 O(VO 4 ) 2 en utilisant des cristaux prepares par reactions a l'etat solide a temperature elevee. Il s'agit d'un compose orthorhombique, Pnma, a 22.7276(9), b 11.5346(4), c 7.4349(3) A, V 1949.09(13) A 3 , Z = 8. La structure a ete resolue par methodes directes et affinee en utilisant les facteurs F 2 de toutes les reflexions uniques jusqu'a un residu Rl = 0.029 (wR2 = 0.052), calcule pour 3052 reflexions uniques observees. Il y a six cations Pb 2 + symetriquement independants dans la structure de Pb 4 O(VO 4 ) 2 . Les liaisons Pb-O des polyedres PbO n vont de 2.23 a 3.42 A; on peut les subdiviser en trois groupes: les liaisons courtes (2.15-2.50 A), intermediaires (2.50-2.70 A) et longues (>2.70 A). Chacun des cations Pb 2 + forme entre trois et cinq liaisons Pb-O courtes ou intermediaires d'un cote du cation, et entre trois et sept liaisons Pb-O plus longues de l'autre cote. L'assymetrie dans la distribution des liaisons autour des cations Pb 2 + decoule de l'activite stereochimique des paires d'electrons isoles 6s 2 . La structure contient des chaines de composition [O 4 Pb 8 ] 8 + qui impliquent des tetraedres O(1)Pb 4 a aretes partagees. Ces chaines sont paralleles a [010] et sont agencees en couches paralleles a (100). Les couches de tetraedres OPb 4 alternent avec des couches contenant des tetraedres VO 4 ainsi que des atomes Pb(1), Pb(3), et Pb(4). La formule structurale de ce compose, Pb 2 [Pb 2 O](VO 4 ) 2 , souligne le fait que certains atomes de Pb ne sont pas lies aux atomes additionnels d'oxygene, O a d d .
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".