Influence of defect chemistry on the electromechanical strain properties of BNT–ST‐based ternary systems

Abstract

AbstractIn this study, the stabilization of ergodicity and electromechanical strain properties of lead‐free ternary 0.75Na1/2Bi1/2TiO3–0.24SrTiO3–0.01ABO3 piezoceramics (BNT–24ST, ABO3 = BaZrO3 (BZ), CaTiO3 (CT), and BiFeO3 (BF)) were investigated. The relaxor state could be stabilized in BZ‐and BF‐modified BNT–24ST ceramics even at room temperature, whereas pure BNT–24ST and CT‐modified ceramics exhibited ferroelectric (FE) behavior. These phenomena were rationalized by analyzing the temperature‐dependent permittivity; detecting the FE‐relaxor phase transition temperature (TF‐R); and investigating features in strain, polarization, and switching current curves. Furthermore, high‐temperature conductivity data showed that relaxor behavior and realization of large strain properties strongly correlated with the concentration of oxygen vacancies in ABO3‐modified BNT–ST ternary systems.