Giant electrostrain response and enhanced energy storage performance in Bi(Zn2/3Ta1/3)O3-modified Bi0.5(Na0.8K0.2)0.5TiO3 lead-free piezoceramics

One of the crucial issues in developing lead-free piezoelectric materials for actuator applications lies in how to achieve large strain responses. Herein, a strategy that strengthens the synergistic contribution of reversible phase transition and ferroelectric domain switching via modulating the ferroelectric-to-relaxor transition temperature (TF-R) was proposed to improve the strain level. Following this strategy, an enhanced strain response was attained by introducing Bi(Zn2/3Ta1/3)O-3 (BZT) into Bi-0.5(Na0.8K0.2)(0.5)TiO3 (BNKT) matrix. The enhanced bipolar strain (S-bi) of 0.50% and the unipolar strain (S-uni) of 0.56% were obtained in BNKT-0.025BZT ceramic, respectively, with corresponding normalized strain d(33)* values of 833 and 933 pm/V (@60 kV/cm). Besides, BNKT-0.05BZT ceramic exhibited excellent energy storage behavior with a recoverable energy storage density W-rec of 1.05 J/cm(3) at 90 kV/cm. These findings demonstrate that BNKT-xBZT ceramics are promising material candidates for actuators and energy storage applications.