Relationship between sintering methods and physical properties of the low positive thermal expansion material Al <sub>2</sub> W <sub>3</sub> O <sub>12</sub>
Bibliographic record
Abstract
Abstract Ceramic materials from the A 2 M 3 O 12 family with near‐zero thermal expansion are good candidates for applications requiring high thermal shock resistance. Considering their inherently low thermal conductivity, the bulk forms of A 2 M 3 O 12 have to present Young's moduli and mechanical strength close to 100 GP a and 100 MP a, respectively, in order to compete with the state‐of‐the‐art materials used to avoid thermal shock. The relationship between sintering, microstructure, and physical properties within the A 2 M 3 O 12 family is generally unknown while the preparation of bulks with high mechanical resistance remains a great challenge. Bulk samples of dense Al 2 W 3 O 12 (96% TD ) have been obtained by pressureless three‐stage sintering ( TSS ) and spark plasma sintering ( SPS ). The Young's moduli and hardness of samples prepared by SPS were 50% higher than that measured for TSS samples and more than 100% in comparison to the Al 2 W 3 O 12 bulk (91% TD ). UV ‐Vis spectroscopy confirmed that A 2 M 3 O 12 phases are wide band‐gap semiconductors (3.11 eV ). When prepared by SPS , black Al 2 W 3 O 12 absorbed light within the visible spectrum due to the introduction of donor sites within the band‐gap. No enhancement of the mechanism causing negative thermal expansion was observed for black Al 2 W 3 O 12 . The mechanical properties achieved were significantly improved over those previously reported in literature for Al 2 W 3 O 12 .
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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 | 0.000 | 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".