Revealing intrinsic and extrinsic piezoelectric contributions in phase coexistence system of PbTiO$_{3}$-BiScO$_{3}$ [揭示相共存体系PbTiO$_{3}$-BiScO$_{3}$中内在和外在压电贡献]

PbTiO3-BiScO3 ceramics possess high piezoelectricity and high Curie temperature simultaneously, presenting a very promising candidate for high-temperature actuators and transducers. Figuring out the underlying piezoelectric mechanisms is of great importance for its application. Herein, we reveal the quantified intrinsic and extrinsic contributions to the high electrostrain of the morphotropic composition with phase coexistence by employing the advanced in situ electrical biasing high-energy synchrotron X-ray diffraction combined with the STRAP (strain, texture, and Rietveld analysis for piezoceramics from diffraction) methodology. An electric field-induced phase transformation is observed between the coexisting tetragonal and rhombohedral phases. It is found that the tetragonal phase contributes most of the domain switching strain, while the predominant lattice strain is from the rhombohedral phase. With phase fraction changes, the quantitative results demonstrate that the field-induced electrostrain is mainly contributed by the intrinsic lattice strain. In contrast, the high irreversible domain switching strain dominates the large remanent strain. It implies that transforming the large remanent strain into reversible strain would be a strategic direction to improve the piezoelectric response. The present results provide a further understanding of the high piezoelectricity and could help to advance the application of PbTiO3-BiScO3.