Effect of Lanthanum Doping Amounts on Properties ofPb_<sub>(1-2x/3)La_x(Ti_0.99Mn_0.01)O₃ Piezoelectric Ceramics

Pb_<sub>(1-2x/3)La_x(Ti_0.99Mn_0.01)O₃ piezoelectric ceramics were prepared by solid-phase sintering method. The effects of lanthanum doping amount (x=0.005,0.045,0.075,0.150,mole fraction) on the lattice constant, piezoelectric anisotropy, dielectric constant, dielectric loss, Curie temperature and mechanical quality factor of the piezoelectric ceramics were studied. The results show that with increasing lanthanum doping amount, the axial ratio of the lattice (c/a) of the piezoelectric ceramics decreased, the anisotropy and the tetragonal structure was weakened, the dielectric loss was reduced, and the mechanical quality factor increased. The La doping was helpful for the improvement of the piezoelectric property, but resulted in the decrease of the piezoelectric anisotropy and the Curie temperature and the increase of the dielectric constant.