Bibliographic record
Abstract
The condensed Pd-Ni-Fe-S phase system was studied at 550 and 400 °C by synthesis in evacuated silica glass tubes and a combination of textural and electron microprobe studies. The monosulfide Fe1-xS-Ni1-xS solid solution persists at both temperatures. Maximum solubility of Pd, exhibited at elevated x values in the mss formula, is 0.7 at.% at 550 °C and up to 0.1 at.% at 400 °C. The field of sulfide melt is reduced to a narrow Ni-Pd rich stripe at 550 °C and is absent at 400 °C. Sulfur contents of the melt are limited to the interval 30-40 at.% S at 550 °C, i.e., it is metal-rich. Retreat of the melt field at 550 °C results in a plethora of phase associations in its place. Compositional fields of alloys associated with melt and of those associated with ∼(Ni,Fe)<sub>3±x</sub>S<sub>2</sub> extend to high Pd contents. Several sulfur-poor associations contain alloys with only low nickel contents, close in composition to Pd3Fe. Shrinkage of the ∼(Ni,Fe)<sub>3±x</sub>S<sub>2</sub> phase field (the β1-β2 pair of Kitakaze et al. 2011) and the appearance of pentlandite represent the most important developments in the phase system between 725 and 400 °C. The ∼(Ni,Fe)<sub>3±x</sub>S<sub>2</sub> phase dissolves up to 2 at.% Pd at 550 °C. Pentlandite associated with Pd-rich phases dissolves up to 4 at.% Pd at 550 °C, and 5.4 at.% Pd at 400 °C. The latter value represents almost 92% Pd occupancy of the octahedral site. At 550 °C, Pdrich pentlandite coexists with sulfide melt which contains between 17 and 47 at.% Pd. The rare occurrences of such Pd-rich pentlandite in nature could indicate the presence of Pd-rich residual melts. Other cases of Pd-rich pentlandite associate with Pdrich alloy or phases like PdS and Pd<sub>2.2</sub>S. In the association with mss, Pd is concentrated in the sulfide melt, especially at a low temperature. At low temperatures or high S fugacities, nickel prefers mss but pentlandite and ∼(Ni,Fe)<sub>3±x</sub>S<sub>2</sub> complicate this simple scheme. For mineral associations with elevated sulfur fugacities, pyrrhotite (mss) appears to be a principal solid-state collector of Pd at high temperatures, with its gradual release on cooling, making it available for subsequent reactions. At low sulfur fugacities Pd concentrates in its Fe-Ni alloys. Because of the inverse relationship between Ni solubility in PdS and the temperature of formation, the composition of natural vysotskite (and Pd-rich braggite) may serve as a temperature indicator.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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 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".