High pressure crystal structure of nitroethane
Bibliographic record
Abstract
Ambient temperature static high pressure compression of liquid nitroethane has been performed using the diamond anvil technique. The first transition to a crystalline powder around 4.2 GPa did not return reliable indexing solutions and could be the result of a mixture of phases. Subsequent cycling of the pressure apparatus with the same sample triggered a solid-solid transition around 4.9-4.3 GPa on the downstroke. Indexing returned a monoclinic structure with spacegroup P21 or P21/m which is consistent with the lowest enthalpy solution predicted from density functional theory (DFT) calculations performed in this study, namely, P21. Attempts to reproduce the first anomalous mixture of phases with other samples were not successful; rather, the numerically preferred monoclinic structure manifests itself after a liquid-solid transition around 4.3-3.6 GPa, a value consistent with the results of a previous study. The transition typically occurs more readily on the downstroke. Incomplete Debye rings resulting from preferred orientation complicates any Rietveld refinement, though the DFT simulations predict 2 molecules per unit cell. Unit cell volumes during the upstroke were within 3% of that predicted by DFT calculations. This departure increases to about 9% below that from DFT predictions during the downstroke suggesting the presence of residual stresses due to non-hydrostatic conditions. Finally, a sudden relief in d-spacing values around 3.7-4.3 GPa during the downstroke is thought to be due to the influence of intermolecular hydrogen bonding.
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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 | 0.000 | 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 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".