Enhanced Thermoelectric Properties of Variants of Tl<sub>9</sub>SbTe<sub>6</sub> and Tl<sub>9</sub>BiTe<sub>6</sub>
Bibliographic record
Abstract
Tl 9 BiTe 6, a substitution variant of Tl 5 Te 3, is one of the leading midtemperature thermoelectrics and is postulated to exceed ZT = 1 above 450 K when prepared by zone-melting and reach ZT = 0.86 at 560 K after hot-pressing. We have prepared the isostructural series Tl 9 Sb 1– x Te 6, Tl 9– x Sb 1+ x Te 6, Tl 9 Bi 1– x Te 6, and Tl 9– x Bi 1+ x Te 6, with x ranging from 0 to 0.05, from the elements in the stoichiometric ratios and determined their thermoelectric properties after hot-pressing. In theory, these tellurides are narrow-gap semiconductors when x = 0, with all elements in common oxidation states, according to (Tl + ) 9 (Sb/Bi) 3+ (Te 2– ) 6 . The as-prepared samples of this 9-1-6 stoichiometry, however, exhibit relatively high electrical conductivity, which decreases with increasing temperature, indicative of the presence of extrinsic charge carriers. The Seebeck coefficient is generally above +100 μV K –1 . Decreasing the Sb and Bi content increases the hole carrier concentration and thus increases the electrical conductivity while decreasing the Seebeck coefficient. The best feature of these thermoelectrics is their low thermal conductivity, which is consistently well below 0.7 W m –1 K –1 . In combination with reasonable electrical conductivity and a high Seebeck coefficient, high ZT values in excess of 1 can also be achieved via simple hot-pressing after experimental optimization of the carrier concentration via introducing deficiencies on the Bi site. Moreover, the variants with Sb instead of Bi exhibit similar thermoelectric performance, a result of the combination of a better electrical performance and higher thermal conductivity.
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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".