Experimental and first-principles investigation of the electronic structure anisotropy of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Cr</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mtext>AlC</mml:mtext></mml:math>
Bibliographic record
Abstract
The anisotropy of the electronic structure of the $\mathit{MAX}$ phase ${\mathrm{Cr}}_{2}\mathrm{AlC}$ has been investigated by electron-energy-loss spectroscopy (EELS) at the C $K$ edge, and x-ray-absorption spectroscopy (XAS) at the Al $K$, Cr ${L}_{2,3}$, and Cr $K$ edges. The experimental spectra were interpreted using either a multiple-scattering approach or a full-potential band-structure method. The anisotropy is found to be small around C atoms because of the rather isotropic nature of the octahedral site, and of the averaging of the empty C $p$ states probed by EELS at the C $K$ edge. In turn, a pronounced anisotropy of the charge distribution around Al atoms is evidenced from polarized XAS measurements performed on textured ${\mathrm{Cr}}_{2}\mathrm{AlC}$ sputtered thin films. From the analysis of the XAS data using the multiple-scattering feff code, it is demonstrated that the probed thin film is constituted of $70%$ (0001) and $30%$ $(10\overline{1}3)$ grains oriented parallel to the film surface. A decomposition of the calculated spectrum in coordination shells allows for the ability to connect XAS fine structures to the ${\mathrm{Cr}}_{2}\mathrm{AlC}$ structure. Combining high-resolution data with up-to-date multiple-scattering calculations, it is shown that the crystalline orientations of the grains present in a probe of $100\ifmmode\times\else\texttimes\fi{}100$ $\ensuremath{\mu}\mathrm{m}{}^{2}$ can be determined from the Cr $K$ edge. Interestingly, it is also revealed that a static disorder is involved in the studied thin films. These findings highlight that, given the overall agreement between experimental and calculated spectra, the ${\mathrm{Cr}}_{2}\mathrm{AlC}$ electronic structure is accurately predicted using density functional theory.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".