Low electric field-driven giant strain response in 〈001〉 textured BNT-based lead-free piezoelectric materials

The applied electric field to drive intended large strain response in Bi_0.5Na_0.5TiO₃-based piezoelectric ceramics is usually high (mostly with E ≥ 60 kV/cm) and remains a long-standing drawback for actual actuator applications. In this work, we report 〈001〉 oriented (1−x) (0.83Bi_0.5Na_0.5TiO₃–0.17Bi_0.5K_0.5TiO₃)–xBaTiO₃ (BNT–BKT–BT) lead-free piezoelectric ceramics using BT as the template particles to tailor the strain behavior under a low driving field. The strain response exhibited an increasing trend with the increasing grain orientation, and remarkably giant S _max/E _max of 800 pm/V was acquired under a relatively low electric field of 45 kV/cm in the optimized microstructure for textured BNT-BKT–1BT ceramics compared with the reported lead-free Bi-based perovskite ceramics. Furthermore, the achieved textured ceramics showed prominent electric field- and temperature-dependent strain characteristic featured by both a high room-temperature S _max/E _max of 621 pm/V under a very low driving field of 35 kV/cm and an achievable large S _max/E _max of 531 pm/V with almost vanished hysteretic behavior at high temperature. Our work may be helpful for designing BNT-based lead-free materials with promising strain response and thus provides a new approach to resolve this drawback of BNT-based lead-free piezoelectric ceramics.