An X-ray and electron microprobe study of Fe, Ni, Ga, and Ge distribution and local structure in a section of the Canyon Diablo iron meteorite
Bibliographic record
Abstract
Using X-rays produced by a third generation synchrotron at the Pacific Northwest Consortium Collaborative Access Team (PNC-CAT), Advanced Photon Source (APS), Argonne National Laboratory, the distribution of Fe, Ni, Ga, and Ge in a sample of the Canyon Diablo iron meteorite has been mapped microscopically in situ with a 5 μm × 5 μm spatial resolution. The principal phases investigated were kamacite (αFe/Ni alloy, <6 wt% Ni), cohenite [a carbide, (Fe,Ni,Co) 3 C], and schreibersite [a phosphide, (Fe,Ni) 3 P]. A non-microscopic X-ray absorption analysis at the P edge indicated the presence of both phosphide and phosphate in the sample. Extended X-ray absorption fine structure (EXAFS) analysis of Fe in kamacite reflects the known bcc structure of kamacite. EXAFS analysis of Ni, Ga, and Ge indicates that these elements substitute for Fe within the kamacite bcc structure. Absorption edge shifts for these same elements are generally small relative to the metals themselves, suggestive of a metallic environment. Initial findings also suggest that Ga preferentially partitions into schreibersite (phosphide) rather than cohenite (carbide), whereas Ge behaves differently and is found principally in the kamacite. These observations further the understanding of the Ge and Ga budget within the Canyon Diablo meteorite, and the work also illustrates the potential of the X-ray microprobe technique for the study of meteorites. Other potential uses of the X-ray microprobe are indicated.
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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) | 0.000 | 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 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".