The formation of nanocrystalline ZrO2 nuclei in a Li2O-Al2O3-SiO2 glass – a combined XANES and TEM study
Bibliographic record
Abstract
Abstract The high economic importance of glass ceramics based on Li 2 O/Al 2 O 3 /SiO 2 (LAS) is mainly due to their low coefficients of thermal expansion (CTE), which make these materials suitable candidates for a number of applications. The exact mechanism of the crystallization processes in LAS glasses is still not fully understood. The present work focuses on the formation and development of nanocrystalline ZrO 2 within an LAS base composition which contains only ZrO 2 as nucleating agent. Using a combination of transmission electron microscopy and X-ray absorption spectroscopy techniques, the temporal evolution of the ZrO 2 nanocrystal formation is described. It is found that the formation of ZrO 2 is initiated by liquid-liquid phase separation droplets with high Zr content, which eventually evolve into the nanocrystalline ZrO 2 precipitations. This process is accompanied by a gradual change of the coordination of the tetravalent Zr ions from sixfold in the glass to eightfold in the crystals. The diameters of the ZrO 2 crystals stay well below 4 nm, even at late stages. The degree of crystallization at each step of the crystallization process is deduced, and from that, the Avrami coefficient n is determined to be n ≈ 1, which describes a barrier-limited crystal growth process.
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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".