Manipulation of defects to achieve fast domain switching and enhance the piezoelectric properties of thin films

High-performance lead-free piezoelectric films play an important role in micro-electromechanical systems (MEMS), and the inevitable defects can affect the performance of the films. In particular, the coupling between defects and domain wall motion can be regarded as a general strategy for regulating the piezoelectric properties of thin films. Here, based on the existing vacancy defects in 0.8Bi0.5Na0.5TiO3-0.2(Sr0.7Bi0.2□0.1)TiO3 system, we control the balance of A-site defects through the introduction of rare earth La ions, release the rapid switching of domain structures and enhance the piezoelectric response of the thin film. The maximum inverse piezoelectric coefficient can reach 425.9 pm V−1. Under the in-situ electric field, a fast response of the domain structure can be observed, which is closely related to the reduction of defect concentration and releasing the pinning effect of domain walls. Also, phase coexistence was observed by TEM, which is attributed to the optimization of MPB by defect regulation. It is hoped that this process of balancing defects can provide a certain reference for the improvement of piezoelectric properties of thin films.