Lead-free piezoelectric ceramics derived from the K0.5Na0.5NbO3–AgNbO3 solid solution system
Bibliographic record
Abstract
A lead-free solid solution between potassium sodium niobate and silver niobate, (1−x)K0.5Na0.5NbO3–xAgNbO3 (KNN-AN, with x=0–0.36), has been prepared in the form of ceramics by solid state reaction under O2 atmosphere. The crystal chemical study shows that Ag+ ion diffuses into the KNN lattices to form a solid solution of perovskite structure with x up to 0.30. The substitution of Ag+ ion for (K0.5Na0.5)+ ion results in linear decreases in the ferroelectric Curie temperature (TC), from 420°C in KNN down to 325°C in 0.70KNN-0.30AN, and in the tetragonal to orthorhombic phase transition temperature (TT-O), from 190 down to 150°C. The relative density of the KNN-AN ceramics reaches 94%. The optimum piezoelectric properties are found in the ceramics of 0.82KNN-0.18AN, with a piezocoefficient d33=186pC∕N, an electromechanical coupling factor kp=42.5%, and a TC=355°C. For the ceramics with x=0.24, the remanent polarization reaches a maximum value of Pr=20μC∕cm2, with a reduced coercive field Ec=6.4kV∕cm and a TC=340°C. It is shown that the (1−x)KNN-xAN ceramics exhibit piezoelectric properties which are comparable or superior to the hot-pressed KNN ceramics and other KNN-based systems. In particular, the piezoelectric properties exhibit very a good thermal stability up to high temperature, which is a significant improvement from other KNN-based piezoceramics.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".