Polarization Rotation Control Domain Dynamic Response Modulates Piezoelectric Properties of Lead‐Free Thin Films

Domain orientation engineering regulates the polarization direction of thin film and facilitates the enhancement of piezoelectric properties. A change in polarization direction implies a structural change in the piezoelectric thin film. In this work, some unexpected results are obtained by preparing three orientations of Bi0.5Na0.5TiO3-based lead-free piezoelectric thin films to amplify this structural change. In distinction to the conventional perception, the piezoelectric properties decrease with increasing polarization direction. This anomaly is influenced by the concentration of structural defects, and rotation of the polarization direction may induce a change in the electronic structure of the material and hence in the concentration of structural defects. Ultimately, the suppression of the domain dynamics response by increasing structural defects leads to the worst piezoelectric properties for thin films with the traditionally perceived optimal (100) orientation. The revelation of this anomaly has implications for the design of the next generation of high-performance piezoelectric thin films.