Large electromechanical strain response in BiFeO3–BaTiO3-based ceramics at elevated temperature

An approach of composition modification in (Bi,Na,Ba,Sr)(Ti,Nb,Zr)O3 (BNSTNZ)–modified 0.65Bi1.05FeO3–0.35BaTiO3 (BF35BT) piezoelectric materials was investigated. Introducing BNSTNZ into BF35BT ceramics led from the normal-ferroelectric to relaxor-ferroelectric- phase. At the optimum composition, large dynamic piezoelectric coefficient (d33*) of 583 pm/V under the applied field of 5 kV/mm and relatively high static piezoelectric coefficient (d33) of 135 pC/N with high maximum temperature (Tm ≤ 400 °C) were obtained. The unipolar strain and d33* of BNSTNZ into BF35BT ceramics with x = 0.005 increased up to 0.251% and 718 pm/V at 90 °C. The remarkably enhanced field-induced strain response of BF35BT-based compositions is believed to be attributed to the optimum grain size, high tetragonality and the ferroelectric-relaxor phase coexistence. It is noted that this composition can be a favorable lead-free candidate for high-temperature piezoelectric applications. •Small amount of (Na,Sr) for A-site and (Nb,Zr) for B-site in BFBT induce large lattice distortion with high tetragonality.•Large dynamic piezoelectric coefficient (d33*) of 583 p.m./V under the applied field of 5 kV/mm at room temperature.•The unipolar strain and d33* increased up to 0.251% and 718 p.m./V at 90 °C.•Large piezoelectric response thanks to optimum grain size, high tetragonality, and ferroelectric-relaxor phase coexistence.