Phase transitions and relaxor behavior of lead-free ferroelectric bismuth potassium titanate
Bibliographic record
Abstract
The phase transition behavior of relaxor ferroelectric Bi1/2K1/2TiO3 (BKT) is investigated in ceramic form based on synchrotron radiation x-ray diffraction (SR-XRD) measurements and dielectric measurements as a function of temperature. The BKT ceramics show a spontaneous phase transition from the non-ergodic relaxor (NER) phase to the ferroelectric phase characterized by an abrupt change in relative permittivity around 310 °C. Analyses of the temperature dependence of dielectric properties reveal that, upon cooling from the high-temperature paraelectric phase, a phase transition to the ergodic relaxor phase associated with the formation of polar nanoregions (PNRs) occurs at the Burns temperature (TB) of 584 °C, and the PNRs are frozen at the freezing temperature (Tf) of 364 °C. SR-XRD measurements for the BKT powders show that the crystal structure transforms from the cubic (Pm3¯m) to the tetragonal (P4mm) in the temperature range of 327–347 °C, which is slightly higher than the temperature of the spontaneous relaxor-to-ferroelectric phase transition. These results indicate that the structural transformation from the cubic NER state to the tetragonal NER state may trigger the spontaneous relaxor-to-ferroelectric phase transition. Based on these experimental observations, a temperature phase diagram of BKT is established in terms of average crystal structure and polar order.
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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 | 0.000 | 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".