Novel bismuth ferrite-based lead-free incipient piezoceramics with high electromechanical response

Abstract

Lead-free piezoceramics with high recoverable strain (or d₃₃*, the large-signal piezoelectric coefficient) and a low degree of hysteresis (Hys) are in great demand for next-generation actuator devices to meet the requirement of sustainable development. Herein, we report a large d₃₃* value of 640 pm V⁻¹ and a low degree of strain hysteresis of 33% in a novel (0.67 − x)BiFeO₃–0.33BaTiO₃–x(Ba_0.8Ca_0.2)ZrO₃ system with x = 2 mol% (BCZ2). A large and linear electrostrictive property (Q₃₃ = 0.029 m⁴ C⁻²) was achieved in the BCZ6 composition. Furthermore, the strain and electrostrictive properties present a robust thermal stability. The salient strain performance of BCZ2 can be explained by a reversible field-induced relaxor-ferroelectric phase transition, while the low strain hysteresis is due to a rapid response of forward and backward switching between relaxor and ferroelectric phases facilitated by the weak nonergodicity. The origin of the superior physical properties was systematically elucidated from the micro- and macroscopic views. Our work suggests that the strategy of engineering relaxor dynamics promises to boost the actuating performances, which may pave the way towards exploiting BiFeO₃-based incipient piezoceramics in high-precision sensor and actuator applications.