High energy storage density and large strain in Bi(Zn2/3Nb1/3)O3-Doped BiFeO3-BaTiO3 ceramics

High recoverable energy density (Wrec ~ 2.1 J/cm3) was obtained in (0.7-x)BiFeO3-0.3BaTiO3-xBi(Zn2/3Nb1/3)O3 + 0.1wt% Mn2O3 (BF-BT-xBZN, x = 0.05) lead-free ceramics at < 200 kV/cm. Fast discharge speeds (< 0.5 μs), low leakage (~ 10-7 A/cm2) and small temperature variation in Wrec (~ 25% from 23 to 150 °C) confirmed the potential for these BiFeO3 based compositions for use in high energy density capacitors. A core-shell microstructure composed of a BiFeO3-rich core and BaTiO3-rich shell was observed by scanning and transmission electron microscopy which may contribute to the high value of energy density. In addition, for x = 0.005, a large electromechanical strain was observed with Spos = 0.463% and effective d33* ~ 424 pm/V, suggesting that this family of ceramics may also have potential for high strain actuators.