Formation of the Ternary Complex Hydride Mg<sub>2</sub>FeH<sub>6</sub> from Magnesium Hydride (β-MgH<sub>2</sub>) and Iron: An Electron Microscopy and Energy-Loss Spectroscopy Study
Bibliographic record
Abstract
We examined the formation of the ternary complex hydride phase Mg 2 FeH 6 during the thermal hydrogen absorption of a ball-milled powder mixture of MgH 2 and Fe. Analytical measurements, scanning transmission electron microscopy, and electron energy-loss spectroscopy, with the sample cooled to liquid nitrogen temperature, were utilized to identify the various phases present and to study the features of this phase transformation. The low-loss region of the electron energy-loss spectrum was mainly used to distinguish various constituents. Mg 2 FeH 6 was initially formed during ball milling of MgH 2 and Fe, demonstrating a co-continuous structure with MgH 2 and Mg. Upon the first desorption, this phase was transformed into elemental Mg and Fe. During the initial stages of the subsequent thermal absorption, MgH 2 was first formed with enhanced kinetics because of the presence of Fe. This was followed by the nucleation of Mg 2 FeH 6 between MgH 2 and Fe and its growth with a columnar morphology. This morphology was dictated by the diffusion direction of the atomic hydrogen from the catalytic Fe cap. As the Mg 2 FeH 6 columns grew, the capping Fe particle and the MgH 2 substrate were consumed. When the system was maintained at high temperature for a long time, these columnar Mg 2 FeH 6 structures coalesced into a semispherical morphology.
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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".