Large strain and strain memory effect in bismuth ferrite lead-free ceramics

Abstract

An electric-field-induced strain in ferroelectric materials has extensive applications in actuators and sensors. BiFeO₃ (BFO) ceramic is a promising candidate for high-temperature electromechanical coupling applications due to its exceptionally high Curie temperature (T_c ∼ 825 °C). Here, we reported an enhanced electric-field-induced strain in defective BFO ceramics. These defective BFO ceramics exhibit highly asymmetric S–E loops along with a strain memory effect. A large peak-to-peak strain (S_p–p) of 0.66% is achieved in the Bi₂O₃-deficient sample with x = −0.15, which is the largest strain value ever obtained in BFO-based ceramics. A strain shape memory of 0.24% is observed in samples with x = 0.09 due to the presence of defects and the orientation of the defect-dipoles. The combination of large strain and high T_C would make the defective BiFeO₃-based ceramics one of the most important candidates for high-temperature electromechanical coupling applications.