Abstract
The microstructural origin of the exceptionally high piezoelectric response of polycrystalline is investigated using in situ transmission electron microscopy, in addition to a wide variety of bulk measurements and first-principles calculations. A direct correlation is established relating a domain wall-free state to the ultrahigh piezoelectric coefficient in this -based composition. The results suggest that the unique single-domain state formed during electrical poling is a result of a structural transition from coexistent rhombohedral and tetragonal phases to an orthorhombic phase that has an anomalously low elastic modulus. First-principles calculations indicate that incorporating and into reduces the differences in structure and energy of the variant perovskite phases, and is identified as unique because the variant phases become almost indistinguishable. The structural instability and elastic softening observed here are responsible for the excellent piezoelectric properties of this lead-free ceramic.
2 More- Received 11 March 2014
- Revised 22 May 2014
DOI:https://doi.org/10.1103/PhysRevB.90.014103
©2014 American Physical Society