Structure Change via Partial Se/Te Substitution: Crystal Structure and Physical Properties of the Telluride Ba<sub>2</sub>Cu<sub>4−<i>x</i></sub>Te<sub>5</sub> in Contrast to the Selenide-Telluride Ba<sub>2</sub>Cu<sub>4−<i>x</i></sub>Se<sub><i>y</i></sub>Te<sub>5−<i>y</i></sub>
Bibliographic record
Abstract
The chalcogenides Ba 2 Cu 4− x Se y Te 5− y were synthesized from the elements in stoichiometric ratios at 700 °C, followed by annealing at 600 °C. The ternary telluride Ba 2 Cu 4− x Te 5 crystallizes in a new structure type, space group C 2/ c, with lattice dimensions of a = 9.4428(6) Å, b = 9.3289(6) Å, c = 13.3028(8) Å, β = 101.635(1)°, V = 1147.8(1) Å 3, for x = 0.75(1) ( Z = 4). The corresponding selenide-telluride adopts another new, but strongly related, structure type, space group P 4 1 2 1 2, with a = 6.5418(3) Å, c = 25.782(2) Å, V = 1103.3(1) Å 3, for Ba 2 Cu 3.26(2) Se 0.729(8) Te 4.271 ( Z = 4). Between 0.13 and 1.0 Te per formula unit can be replaced with Se, while the Cu content appears to vary only within 0.67 ≤ x ≤ 0.81 for Ba 2 Cu 4− x Se y Te 5− y . Despite crystallizing in different crystal systems, the telluride and the selenide-telluride exhibit topologically equivalent structure motifs, namely, chains of Cu(Se,Te) 4 tetrahedra with a Cu atom cis/trans chain as well as an almost linear Te atom chain. All these chalcogenides, as far as measured, are p -doped semiconductors, as determined by Seebeck coefficient and electrical conductivity measurements.
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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".