Optimized electrostrain with minimal hysteresis at the MPB in BNT-based ceramics

Abstract

Lead-free (Bi_0.5Na_0.5)TiO₃ (BNT)-based ceramics play a vital role in transducers and sensors, owing to their pronounced electrostrain response under applied electric fields. This work presents a notable electrostrain response of 0.54 % with minimal electrostrain hysteresis (11 %) in the x = 0.30 composition near the morphotropic phase boundary (MPB) within (1–x)BNT-x(Ba_0.15Sr_0.55Ca_0.3)TiO₃ (x = 0.2–0.4, BNT-xBSCT) ceramics. By exploiting the variation in tolerance factor through titanate doping and localized disorder from A-site multiple ion substitution, we achieved enhanced electrostrain response via the evolution of nonergodic relaxor (NR) and ergodic relaxor (ER) phase boundaries. Notably, the x = 0.30 composition exhibits ultrahigh electrostrain (>0.5 %) with remarkable thermal stability above 70 °C. This stability arises from the combined effects of domain flipping in ER/NR mixed phases and reversible electric field-induced relaxor-to-ferroelectric phase transitions. These results hold significant potential for advancing electrostrain performance and thermal stability in lead-free BNT-based ceramics.