EPR and Uniaxial Pressure Measurements of the Phase Transition in (NH 4 ) 2 SO 4 Crystal
Bibliographic record
Abstract
The uniaxial-pressure dependence of the phase transition temperature in (NH 4 ) 2 SO 4 was measured for the first time along the three crystal axes. The splitting of EPR lines caused by the structure change was taken as signature indicating T c temperature. The phase transition temperature is shifted by the uniaxial pressure along a , b , and c axes at the linear rate dT c / dX a = ( m 9.5 - 0.2) K/kbar, dT c / dX b = (0.0 - 0.2) K/kbar, dT c / dX c = (5.3 - 0.2) K/kba, respectively. The values of the three rates are consistant with the hydrostatic pressure measurements of dT c / dp and confirm the reliability of the uniaxial-stress measurements. Large anisotropy of the uniaxial pressure coefficients dT c / dX i together with the temperature dependence of the EPR lines in the paraelectric and ferroelectric phase is discussed in terms of previously proposed models of the mechanism of the phase transition. The driving force of the phase transition is related to the dynamics of SO 4 -NH 4 (I) groups. Below T c , NH 4 (I) groups become ordered and their orientation is fixed, while NH 4 (II) groups gradually change their orientation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 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".