Achieving giant electrostrain of above 1% in (Bi,Na)TiO3-based lead-free piezoelectrics via introducing oxygen-defect composition

作者：Luo, Huajie; Liu, Hui; Huang, Houbing; Song, Yu; Tucker, Matthew G.; Sun, Zheng; Yao, Yonghao; Gao, Baitao; Ren, Yang; Tang, Mingxue; Qi, He; Deng, Shiqing; Zhang, Shujun^*; Chen, Jun^*

来源：Science Advances, 2023, 9(5): eade7078.

DOI：10.1126/sciadv.ade7078

• FIELD-INDUCED STRAIN
• FERROELECTRIC DOMAIN-STRUCTURES
• X-RAY-ABSORPTION
• THIN-FILMS
• CERAMICS
• TRANSITION

Piezoelectric ceramics have been extensively used in actuators, where the magnitude of electrostrain is key in-dicator for large-stroke actuation applications. Here, we propose an innovative strategy based on defect chem-istry to form a defect-engineered morphotropic phase boundary and achieve a giant strain of 1.12% in lead-free Bi0.5Na0.5TiO3 (BNT)-based ceramics. The incorporation of the hypothetical perovskite BaAlO2.5 with nominal oxygen defect into BNT will form strongly polarized directional defect dipoles, leading to a strong pinning effect after aging. The large asymmetrical strain is mainly attributed to two factors: The defect dipoles along crystallographic [001] direction destroy the long-range ordering of the ferroelectric and activate a reversible phase transition while promoting polarization rotation when the dipoles are aligned along the applied electric field. Our results not only demonstrate the potential application of BNT-based materials in low-frequency, large -stroke actuators but also provide a general methodology to achieve large strain.

• 单位
  北京科技大学; 北京理工大学