Large Strain and Low Hysteresis in BNT‐based Ceramics via Domain Structure Design and Electrobending Deformation

ABSTRACT

In practical piezoelectric actuators, materials are required to exhibit large electrostrain for substantial displacement output while maintaining low strain hysteresis to ensure high positioning accuracy. However, these two performance metrics are often mutually exclusive. This study employs hierarchical domain structure engineering to synergistically regulate electrobending‐induced strain amplification and domain switching behavior, thereby overcoming the aforementioned trade‐off. Based on phase‐field simulations, a hierarchical domain structure constructed by embedding micron‐scale lamellar domains within a nanodomain matrix is demonstrated to simultaneously optimize strain magnitude and strain hysteresis. Furthermore, the magnitude of the bending response is found to be governed not only by oxygen vacancy concentration but also by the domain structure. Compared with polar nanoregions, lamellar domains are more susceptible to pinning by oxygen vacancies, leading to heterogeneous strain distribution and electrobending deformation. Specifically, the (Bi _0.5 Na _0.5 ) _0.7 Sr _0.3 Ta _0.002 Ti _0.998 O ₃ sample exhibits the optimal overall performance, achieving an apparent strain of ∼0.74%, an apparent large‐signal piezoelectric coefficient of 1067 pm/V, and a low hysteresis rate of ∼21%, demonstrating superior strain–hysteresis synergistic optimization compared with the undoped and excessively Ta‐doped samples. These results demonstrate that hierarchical domain design and electrobending engineering provide a viable strategy for synergistically achieving large strain and low hysteresis, offering a new pathway for high‐performance piezoelectric bending actuators.