Bibliographic record
Abstract
The crystal structure of kudriavite, (Cd,Pb)Bi 2 S 4 , a new mineral species, was solved from single-crystal X-ray-diffraction data and refined to R = 4.9% (4.3% for a model with split mixed-cation sites). Lattice parameters are a 13.095(1), b 4.0032(3), c 14.711(1) A, β 115.59(1)°, V 695.6(1) A 3 . The structure is equivalent to that of synthetic CdBi 2 S 4 , space group C 2/ m , Z = 4, and represents a pavonite homologue, N = 3. It is built of three-octahedron-thick columns of (311)PbS-like slabs combined by “unitcell twinning” in a quasi-mirror-glide succession. The slabs, which are intrinsically of the same topology, differ in the coordination state of bordering cations because of the relative positions of the adjacent layers. In the slabs of type I (the “non-accreting” slab common to all pavonite homologues), the central columns of octahedra are flanked by half-octahedral (square-pyramidal) coordinations completed to split-octahedra by the addition of two S atoms from the adjacent slab. The central columns of octahedra in the slabs of type II (of varying thickness, i.e. , “accreting” in pavonite homologues) are flanked by octahedral coordinations involving a S atom from the adjacent slab. The observed chemical Cd ↔ Pb and Bi ↔ In substitutions are, according to the crystal-chemical analysis, structurally limited to Bi-containing sites. They are distributed predominantly in the boundary coordinations of the type-I slabs, and the central octahedra of the type-II slabs, with Pb preferentially entering the former, and In the latter. The marginal octahedral sites of the type-II slabs, and the central octahedral sites of the type-I slabs, have been refined as pure Bi and Cd sites, respectively. The crystal-chemical analysis suggests that the observed 1:1 Pb:Cd ratio in natural kudriavite represents the upper limit for the substitution of Pb in the structure. A limit of the In substitution is not possible to determine from the present data, but it most probably is less than In:Bi = 1:3. The ratio observed in type kudriavite is less than 1:10.
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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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".