Effect of synthesis method and reaction conditions on the long-range and local structure of RE<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub> pyrochlore-type oxides
Bibliographic record
Abstract
Current plans for managing high-level nuclear waste may involve sequestration in borosilicate glass and potential disposal in geological repositories. However, there is considerable interest in using ceramic oxides, such as pyrochlores, as alternative nuclear waste forms due to the high chemical durability and waste loading capabilities of these materials. The ceramic method is often used to synthesize RE 2 Ti 2 O 7 pyrochlore-type oxides and requires the use of high temperatures and long reactions times, making this process less economically feasible for large-scale production. Solution-based synthetic routes, such as co-precipitation and sol–gel methods, have been shown to require much lower reaction temperatures by reducing diffusion distances between reactants. This work studied the effect of using these synthetic methods to synthesize RE 2 Ti 2 O 7 (RE = Gd, Yb). The resistance to radiation induced damage of these materials was also investigated. Phase transitions in RE 2 Ti 2 O 7 were investigated using powder X-ray diffraction, X-ray absorption near-edge spectroscopy (XANES), and extended X-ray absorption fine structure. Changes to the structure of ion-implanted materials were investigated using glancing-angle (GA-)XANES. This study demonstrated that solution-based methods used to mix the reactants can allow for the formation of Yb 2 Ti 2 O 7 adopting primarily the pyrochlore-type structure when annealed at temperatures as low as 1000 °C while Gd 2 Ti 2 O 7 adopting the pyrochlore-type structure could be formed using annealing temperatures as low as 800 °C. It was also observed that changing the synthetic method, annealing temperature, annealing time, and having only the pyrochlore structure present or a mixture the pyrochlore- and defect-fluorite type structures did not affect the resistance to radiation induced structural damage of Yb 2 Ti 2 O 7 or Gd 2 Ti 2 O 7 .
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 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 teacher head, 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".