Mechanosynthesis of Nanocrystalline MgB<sub>2</sub> Ceramic Powders in Hydrogen Alloying Mills via Amorphous Hydride Intermediate
Bibliographic record
Abstract
In the present work we report on the synthesis of nanocrystalline MgB2 by mechanochemical reaction (mechanosynthesis) conducted in a high-energy mechanical alloying mill filled with hydrogen. The solid-state reaction of mechanochemical alloying between Mg and B with H (hydrogen alloying) leads to formation of an intermediate amorphous (Mg,B)Hx hydride. This amorphous intermediate is subsequently annealed (devitrified) to nucleate and grow nanocrystalline boride. The first stage of synthesis was carried out at room temperature from elemental Mg and B powders in a high-energy ball mill under sequential supply of hydrogen. The subsequent annealing of the amorphous product led to nearly single-phase MgB2, with only small fraction of MgO impurity. The easy room-temperature synthesis renders the method promising for production of MgB2, which recently gained attention as a new 39K ceramic superconductor. The amorphous intermediate itself can be studied further for its capacity to store ca. 2 wt% H in a metastable hydride phase. The effort was undertaken to predict formation of amorphous hydride phase through analysis of atomic volume mismatch between atoms of Mg, B, and H.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 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".