Ultrahigh Electrobending Deformation In Poled Sodium Bismuth Titanate-Based Piezoelectric Ceramics by Uneven Defect Distribution

Recent studies have shown that piezoelectric materials containing defects can exhibit significant electrobending, leading to ultrahigh apparent strain and asymmetric strain-electric field curves. The mechanism of electrobending deformation is particularly important and how to achieve electrobending in ferroelectric ceramics is a significant research topic. In this work, sodium bismuth titanate-based (NBT) ceramics, typical lead-free ferroelectrics, are designed to demonstrate the correlation between the poling process and electrobending. It is found that the internal electric field and ultrahigh electrobending properties can be induced by the poling process. The testing modes are further modified to distinguish the electrobending deformation and electrostrain, revealing that poled ceramics exhibit a bent state. High-temperature poling can induce redistribution of defect dipoles on the bottom and top surfaces of the ceramics, resulting in bending. This work demonstrates that high-temperature polarization is a simple and convenient method for inducing electrobending deformation in defect-containing NBT-based piezoelectric ceramics. It also provides valuable insights for future research on the electrobending phenomenon.