Effects of Dy/Tb Co-Doping on Microstructure and Electrical Properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 Lead-Free Ceramics

[(Ba0.85Ca0.15)(1-x)(Dy0.5Tb0.5)(x)](Zr0.1Ti0.9)O-3 (x mol% Dy/Tb-BCZT, x = 0.1, 0.5, 1 and 3 mol%) lead-free ceramics were prepared by solid state reaction method, in which the effects of Dy/Tb doping amount and sintering temperature on structure and electrical properties were investigated. The optimal sintering temperature for preparing the x mol% Dy/Tb-BCZT ceramics decreases with the increase of Dy/Tb doping amount, and the samples' grain size decreases and relative density increases. All ceramics present pure perovskite structure, in which phase structure and phase proportion are affected by Dy/Tb doping content and sintering temperature, and a small amount of Dy/Tb co-doping enhances the dielectric, ferroelectric and piezoelectric properties significantly. The effects of three different poling methods on the piezoelectric properties of ceramics were compared. The best comprehensive performance is obtained for the x = 0.5 mol% ceramics, in which inverse piezoelectric coefficient d(33)* = 502.3 pm V-1 is obtained by alternating current poling, and piezoelectric constant d(33) = 306 pC/N is obtained by pulse poling. The electrical conductivity at high temperatures of all ceramics is controlled by oxygen vacancy conduction determined by calculating the relevant activation energy. The results show that the 0.5 mol% Dy/Tb co-doped BCZT ceramics have well application prospect in future electronic device materials.