Perovskite-Type Oxides Synthesized by Reactive Grinding
Bibliographic record
Abstract
Perovskite type-materials LaCo (1-x) Fe x O 3 were prepared from their component oxides using mechano-synthesis, a new method of preparation designated as reactive grinding. When grinding additives are used, the perovskites generated via this process are of unprecedently high specific surface area (>100 m 2 /g) and their surface chemical properties are of particular interest. The perovskite surface shows a large concentration of surface OH's (due to the low grinding temperature) which upon calcination leads to reformation of the materials lattice. The presence of oxygen during calcination initiates a competitive process, which stabilizes sites with an excess of electronic charge, yielding reduced Co sites upon oxygen desorption (Co 2+ ).At high calcination temperature (> 673 K), TPD studies show the release of β-oxygen originating from the bulk. In this work, the catalytic properties in the n-hexane oxidation reaction of five nanocrystalline LaCo (1-x) Fe x O 3 perovskites prepared by this method are studied. The low preparation temperature allows to stabilize high surface area (SSA) materials and the adequate control of the calcination conditions allows to tailor the surface properties of these materials. Through a kinetic study of the total oxidation of n-hexane by oxygen, the fine control of the nature and the concentration of the various sites active in oxido-reduction catalysis is demonstrated. Furthermore, the roles of two oxygen species O 2 - and O - respectively associated with a and β oxygens are discussed.
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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".