Orthorhombic-tetragonal phase transition induced by Ta isovalent doping and its effect on fatigue characteristics of KNL-NSTx ceramics
Journal article, Peer reviewed
Accepted version
![Thumbnail](/ntnu-xmlui/bitstream/handle/11250/2598852/Namsar%20et%20al%202018.pdf.jpg?sequence=7&isAllowed=y)
Åpne
Permanent lenke
http://hdl.handle.net/11250/2598852Utgivelsesdato
2018Metadata
Vis full innførselSamlinger
- Institutt for materialteknologi [2549]
- Publikasjoner fra CRIStin - NTNU [38294]
Sammendrag
The effect of Ta addition on the bipolar fatigue characteristics of lead-free KNL-NSTx ceramics (x = 0, 0.04, 0.07 and 0.11 mol%) is studied. Bipolar cycling up to 1 × 106 cycles leads to strong degradation of the polarization in unmodified KNL-NS ceramics. This can be explained by the development of strong domain wall pinning, leading to the build-up of high local stresses and consequently microcracking of the material. The addition of Ta reduces the domain wall pinning effect and improves the bipolar fatigue resistance. In order to understand the fatigue mechanism, a model based on oxygen vacancy accumulation is proposed. This model is expected to guide future fatigue studies that are concerned with novel lead-free KNN-based materials.