Noncentrosymmetric Mixed Chalcogenide Semiconductors La<sub>3</sub>Ga<sub>1.67</sub>(S<sub>1–<i>x</i></sub>Se<i><sub><i>x</i></sub></i>)<sub>7</sub>
Bibliographic record
Abstract
The mixed chalcogenides La 3 Ga 1.67 (S 1– x Se x ) 7 form a complete solid solution, with members at increments of x = 0.14 prepared as phase-pure samples. Based on their powder X-ray diffraction (XRD) patterns, the cell volume increases with greater Se substitution, but the cell parameters vary in a nonmonotonic way. Single-crystal XRD studies at room temperature indicated that they adopt noncentrosymmetric hexagonal structures (in space group P 6 3 ) containing stacks of Ga-centered tetrahedra and stacks of octahedra with partially occupied Ga sites. Strong preferences of S vs Se atoms within three types of chalcogen sites lead to unusual structural changes in the intermediate members of the solid solution and can be understood in terms of the need to satisfy optimum bonding requirements. Structure determination of the selenide end-member La 3 Ga 1.67 Se 7 at low temperature (100 K) revealed a supercell (in space group P 6 1 ) with a tripled c -axis characterized by distortions of the partially occupied Ga sites and the coordinating Se atoms, which help relieve bond strain. Two Ga sites in tetrahedral and roughly octahedral geometry were assigned by 71 Ga solid-state nuclear magnetic resonance spectroscopy. The experimental optical band gaps vary from 2.6 eV for La 3 Ga 1.67 S 7 to 2.0 eV for La 3 Ga 1.67 Se 7 .
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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".