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 (T_F−R) was proposed to improve the strain level. Following this strategy, an enhanced strain response was attained by introducing Bi(Zn_2/3Ta_1/3)O₃ (BZT) into Bi_0.5(Na_0.8K_0.2)_0.5TiO₃ (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 d₃₃^* 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/cm³ at 90 kV/cm. These findings demonstrate that BNKT-xBZT ceramics are promising material candidates for actuators and energy storage applications. [ABSTRACT FROM AUTHOR]