Acoustic anomalies and central peak in SrBi2Ta2O9 single crystals studied by micro-Brillouin scattering
Bibliographic record
Abstract
Acoustic properties of layered perovskite SrBi2Ta2O9 (SBT) single crystals were investigated by micro-Brillouin scattering. Two elastic stiffness coefficients, c33 and c44, defined within the pseudotetragonal crystallographic axes, and the corresponding sound velocities were determined in the temperature range between 290 and 773 K. The longitudinal sound velocity propagating along the pseudotetragonal c axis was found to be very small, which can be related to the weak interlayer bonding of SBT. The corresponding c33 shows marked softening on approaching the ferroelectric phase transition temperature Tc around 600 K from both high- and low-temperature sides. The hypersonic attenuation increases markedly around Tc, which seems to reflect not only the bilinear coupling between the order parameter and the strain in the ferroelectric phase, but also the electrostrictive coupling in the paraelectric phase. Furthermore, a quasielastic central component was observed near Tc, which is believed to be partly responsible for the change of the low-frequency dielectric permittivity at Tc, besides the contributions from the soft mode and the low-frequency dielectric dispersion.
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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 | 0.000 |
| 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".