Large electrostrain achieved in BNKT‐based ceramics by the adjustment of phase boundary with Ba(Sn0.70Nb0.24)O3 addition

Abstract In the current study, the incorporation of Ba(Sn 0.70 Nb 0.24 )O 3 (BSN) effectively modifies the phase boundary of the 0.8(Bi 0.50 Na 0.50 )TiO 3 ‐0.2(Bi 0.50 K 0.50 )TiO 3 (BNKT) lead‐free ceramic material, inducing enhanced electrostrain properties at room temperature, particularly results in a “bud‐like” strain profile without negative strain. A comprehensive investigation has been conducted into the microstructure, electrical properties, and electrostrain properties of the above‐mentioned ceramics. The addition of BSN was observed to be well incorporated into the BNKT crystal structure, forming a single perovskite structure according to the X‐ray diffraction pattern. With the increase in BSN solid solution content, the temperature at which the transition from ferroelectric to the relaxor phase occurs shifted from 88.1°C to beneath room temperature (30°C). Specifically, the BNKT‐0.0075BSN ceramic demonstrated a positive strain response of 0.459% along with a large signal piezoelectric coefficient ( d 33 * ) of 643 pm/V. Additionally, the strain hysteresis of the BNKT‐0.0175BSN ceramics was only about 3% at 120°C. These experimental findings suggest that BNKT‐ x BSN ceramics could be strong contenders for actuators and sensors, presenting promising opportunities for lead‐free ceramic actuator applications.