Comprehending the potential correlation between strain performances and phase boundary characteristics of BNT-based systems

Bi0.5Na0.5TiO₃ (BNT)-based systems are potential candidates for actuators due to their outstanding strain performances. Despite various doping components having been utilized to regulate their strain performances, the systematical route for designing giant-strain BNT-based materials remains elusive. Herein, we decode the potential correlation between strain performances and phase boundary characteristics and then propose a complete guideline for designing BNT-based materials with the giant strain. Since the polarization rotation is closely correlated to the phase transition process, the morphology phase boundary (MPB) frame of initial BNT matrix can maintain its partial properties for the polarization rotation, when introducing bits of doping components to tailor the transition temperature. The screened K6LT matrix with the optimized MPB frame exhibits a d₃₃ of 260 pC/N, and the (Zr0.5Nb0.5)-modified K6LT matrix (K6LT-ZN1) exhibits a low driving field Eₚₒₗ~38.4 kV/cm and high large-signal piezoelectric coefficient d33@60*_~727 pm/V. This proposed design guideline reveals the significance for BNT matrix screening and could be a feasible method for constructing BNT-based systems with excellent strain performances.