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)O-3 (BNSTNZ)-modified 0.65Bi(1.05)FeO(3)-0.35BaTiO(3) (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 (d(33)*) of 583 pm/V under the applied field of 5 kV/mm and relatively high static piezoelectric coefficient (d(33)) of 135 pC/N with high maximum temperature (T-m <= 400 degrees C) were obtained. The unipolar strain and d(33)* of BNSTNZ into BF35BT ceramics with x = 0.005 increased up to 0.251% and 718 pm/V at 90 degrees 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.