Large electric-field-induced strain and energy storage properties in Bi_0.5Na_0.5TiO₃-(0.5Ba_0.7Ca_0.3TiO₃-0.5BaTi_0.8Zr_0.2O₃) lead-free relaxor ferroelectric ceramics

Piezoelectric ceramics with high strain can convert electrical energy and mechanical energy into each other for a wide range of applications. (1-x)Bi_0.5Na_0.5TiO₃-x(0.5Ba_0.7Ca_0.3TiO₃-0.5BaTi_0.8Zr_0.2O₃) (BNT-x(BCT-BZT)) lead-free piezoelectric ceramics were prepared through solid-state reaction methods. The structural, dielectric, field-induced strain and energy storage properties of the ceramics were investigated systematically by various characterization techniques. A large field-induced strain of 0.42% with negligible negative strain and large reverse piezoelectric coefficient of 547 pm/V are obtained in BNT-9(BCT-BZT) ceramics. A large recoverable energy storage of 3.49 J/cm³ under 360 kV/cm and high energy storage efficiency of 64.9% are achieved in the BNT-10(BCT-BZT) ceramics. It believes that the large strain with negligible negative strain is mainly due to the crossover of relaxor nonpolar state to ferroelectric polar state. We believe that the BNT-x(BCT-BZT) ceramics are favorable for the practical applications in the mobile electronic devices.