Study on Ce and La Doped 0.85NBT-0.144KBT-0.006BT Lead-free Piezoelectric Ceramics

0.85(Na0.5Bi0.5)TiO3-0.144(K0.5Bi0.5)TiO3-0.006BaTiO(3)(0.85NBT-0.144KBT-0.006BT) lead-free piezoelectric ceramics was prepared by conventional ceramic technique. The influence of La2O3 doping amount and CeO2 doping amount on properties, crystal structure and surface topography of 0.85NBT-0.144KBT-0.006BT ceramics were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and other analytic methods. It shows that all compositions show the characteristics of pure perovskite structure solid states, La2O3 and CeO2 doping only changes crystal cell dimension rather than crystal structure. The piezoelectric strain constant (d(33)) starts increasing and then decreasing, the dielectric constant (epsilon(T)(33)/epsilon(0)) increases, the dielectric loss (tan delta) starts increasing and then decreasing and then increasing while La2O3 doping amount increasing. d(33) and epsilon(T)(33)/epsilon(0) of ceramics starts increasing and then decreasing, tans decreases while CeO2 doping amount increasing. When the La2O3 doping amount is up to 0.4 wt.%, the doped samples show good performances with d(33)=151 pC/N, epsilon(T)(33)/epsilon(0)=1543 and tan delta=4.3%. When the CeO2 doping amount is 0.1 wt.%, the doped samples show good performances with d(33)=156 pC/N, epsilon(T)(33)/epsilon(0)=1364 and tan delta=3.8%. La2O3 doping promotes crystal grain growth, CeO2 doping makes grain crystal size uniform, changes tetragonal into granular structure and restrains crystal grain growth.