Phase transition studies for powder and amorphous materials under high pressure
Bibliographic record
Abstract
Low and high pressure structures of krypton, xenon and argon clathrate hydrates have been studied in situ and in pressure quench recovered forms using high energy (100 keV) synchrotron x-ray scattering (HEXRD) and nuclear magnetic resonance techniques.In addition to standard structural refinements, HEXRD over a wide momentum transfer range has been used to produce Fourier difference maps and pair distribution functions of these structures that indicate the guest electron density.Using relatively simple and higher atomic number inert gas atoms as guests provides enhanced scattering contrast between the guest and the host and allows greater insight into the guest positions and short to intermediate range intercage correlations/disorder of the guest atoms.For krypton hydrate, the low pressure structure II form indicates an enhanced degree of cage-tocage guest disorder, above that accounted for by ordinary crystalline models.The high pressure hexagonal forms have been produced and successfully quench recovered.The geometry of the large cage guest clusters and intercage guest disorder of this structure are indicated.For the xenon hydrate, we describe the structural refinements for the low pressure structure I form and the in situ high pressure hexagonal form, including descriptions of the guest clustering in the large cages.Structural transformation processes occurring on decompression and recovery of high pressure hexagonal xenon hydrate are also discussed.From the initial low pressure argon hydrate structure I, a filled ice structure is produced above 2.0 GPa, and the structure of this form along with a description of its compressibility is given.ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".