Large electrostrictive coefficient with high electro‐strain dominated by modified ergodic state in BNT‐based solid solutions

Abstract For ferroelectric electrostrictors, shifting their Curie temperature T C to the ambient temperature is an effective way to enhance their electrostrictive effect. However, the enhanced electrostrictive coefficient Q 33 in this way is often accompanied with an inferior electro‐strain. In this work, by introducing CaZrO 3 /BaZrO 3 as the special kind of solid solution, with an effective regulation on the ergodic state, we simultaneously realize a larger room‐temperature electrostrictive coefficient Q 33 (~0.04337 m 4 /C 2 ) with a superior electro‐strain (~0.41%) in Bi 0.5 Na 0.5 TiO 3 ‐based relaxor ferroelectric ceramics. The ions substitution with larger radius in either A‐site or B‐site of perovskite structure tends to facilitate the evolution from ferroelectric tetragonal phase P4mm to relaxor tetragonal phase P4bm along with the decrease in polarity in crystal, thereby shifting the transition temperature T F‐R below room temperature. As a result of the effective regulation on the ergodic state, a large electro‐strain with low hysteresis, just like electrostrictors, is successfully realized in BNT‐based ferroelectric ceramics. Our investigation provides an effective way to simultaneously enhance the electrostrictive coefficient Q 33 and electro‐strain for practical applications in precisely controlled displacement.