Manganese-Substituted Rare-Earth Zinc Arsenides <i>RE</i><sub>1–<i>y</i></sub>Mn<sub><i>x</i></sub>Zn<sub>2–<i>x</i></sub>As<sub>2</sub> (<i>RE</i> = Eu–Lu) and <i>RE</i><sub>2–<i>y</i></sub>Mn<sub><i>x</i></sub>Zn<sub>4–<i>x</i></sub>As<sub>4</sub> (<i>RE</i> = La–Nd, Sm, Gd)
Bibliographic record
Abstract
Two series of Mn-substituted rare-earth zinc arsenides RE(1-y)Mn(x)Zn(2-x)As2 (RE = Eu-Lu) and RE(2-y)Mn(x)Zn(4-x)As4 (RE = La-Nd, Sm, Gd) were prepared by reaction of the elements at 750 °C. Both series are derived from ideal empirical formula REM2As2 (M = Mn, Zn) and adopt crystal structures related to the trigonal CaAl2Si2-type (space group P3m1) in which hexagonal nets of RE atoms and [M2As2] slabs built up of edge-sharing M-centered tetrahedra are alternately stacked along the c-direction. For compounds with divalent RE components (Eu, Yb), the fully stoichiometric and charge-balanced formula REM2As2 is obtained, with Mn and Zn atoms statistically disordered within the same tetrahedral site. For compounds with trivalent RE components, the RE sites become deficient, and the Mn atoms are segregated from the Zn atoms in separate tetrahedral sites. Within the series RE(1-y)Mn(x)Zn(2-x)As2 (Gd-Tm, Lu), the parent CaAl2Si2-type structure is retained, and the Mn atoms are disordered within partially occupied interstitial sites above and below [Zn(2-x)As2] slabs. Within the series RE(2-y)Mn(x)Zn(4-x)As4 (RE = La-Nd, Sm, Gd), the c-axis becomes doubled as a result of partial ordering of Mn atoms between every other pair of [Zn(2-x)As2] slabs. Attempts to synthesize Gd-containing solid solutions with the charge-balanced formula Gd0.67Mn(x)Zn(2-x)As2 suggested that these phases could be formed with up to 50% Mn substitution. Band structure calculations reveal that a hypothetical superstructure model with the formula La1.33MnZn3As4 would have no gap at the Fermi level and that slightly lowering the electron count alleviates antibonding Mn-As interactions; a spin-polarized calculation predicts nearly ferromagnetic half-metallic behavior. X-ray photoelectron spectroscopy confirms the presence of divalent Mn in these compounds.
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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 | 0.020 | 0.012 |
| Meta-epidemiology (narrow) | 0.023 | 0.027 |
| Meta-epidemiology (broad) | 0.019 | 0.009 |
| Bibliometrics | 0.006 | 0.018 |
| Science and technology studies | 0.012 | 0.019 |
| Scholarly communication | 0.012 | 0.013 |
| Open science | 0.020 | 0.015 |
| Research integrity | 0.016 | 0.024 |
| Insufficient payload (model declined to judge) | 0.001 | 0.020 |
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; both teacher heads agree on what is shown here.
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".