Enhanced piezoelectric properties by reducing leakage current in Co modified 0.7BiFeO3-0.3BaTiO3 ceramics

Co modified lead-free 0.7BiFeO3− 0.3BaTiO3 (0.7BFO-0.3BT-xCo2O3；x = 0, 0.3, 0.6, 0.9 and 1.2) piezoelectric ceramics were prepared by a conventional solid-state reaction. The effect of Co doping on the structural, piezoelectric properties and leakage current was investigated. A greatly reduced leakage current and dramatically improved piezoelectric properties were achieved in x = 0.3 Co doped ceramic. The maximum d33 = 151 pC/N and kp = 0.32 were obtained at x = 0.3 addition due to the co-effect of maximum applied poling electric field and large grain size. The X-ray photoelectron spectroscopy (XPS) analysis and complex impedance data indicated that the greatly reduced leakage current could be attributed to the effect of suppressing Fe2+ ion formation and promoting grain boundary resistance by Co doping. These results strongly suggest that low concentration of Co doping is a good strategy to improve the resistance and piezoelectric properties simultaneously in BFO-based lead-free piezoceramics.