Contrasting Structural Stabilities and New Pressure-Induced Polymorphic Transitions of Scheelite- and Zircon-Type ZrGeO<sub>4</sub>
Bibliographic record
Abstract
As promising optical materials, the structures of scheelite- and zircon-type ZrGeO 4 have been investigated by Raman spectroscopy at pressures up to 51.6 GPa using diamond anvil cells. For scheelite-type ZrGeO 4, two reversible phase transitions at 16.2 and 41.2 GPa were identified from the Raman spectral profiles and pressure dependence of the Raman shift upon compression. The first transition can be interpreted as the change of the tetragonal scheelite structure to the monoclinic fergusonite structure. By comparison with a previously reported isomorphic crystal, we infer that the second high pressure phase likely has a monoclinic structure. The zircon-type ZrGeO 4 initially transforms to a scheelite structure at ∼10.1 GPa, while such phase transformation is completed at around 24.6 GPa, and remains stable up to 37.6 GPa. Moreover, the zircon-to-scheelite phase transition is irreversible, and the high pressure scheelite structure cannot be recovered upon decompression. These phase transitions for different starting ZrGeO 4 materials were unambiguously identified for the first time, and their contrasting structural stabilities as well as the transition mechanisms can be understood from the intrinsic characteristics of the crystal lattices. These results contribute to the understanding of the pressure behavior of very sparsely reported germinate compounds in the ABO 4 family.
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".