The morphotropic phase boundary and dielectric properties of xPb(Mg1/3Nb2/3)O3 -(1-x)Pb(Zr0.48Ti0.52)O3 piezoelectric ceramics

Piezoelectric ceramics xPb(Mg1/3Nb2/3)O3 -(1-x)Pb(Zr0.48Ti0.52)O3 (PMN-PZT, x = 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, mole fraction) near the morphotropic phase boundary (MPB) were prepared using the columbite precursor method. A single perovskite phase was identified by the X-ray diffraction and Raman spectra results for all specimens. The phase transition from tetragonal to rhombohedra was also observed with increasing PMN mole fraction. The coexistence of the tetragonal and rhombohedral phases is identified near the 0.2PMN-0.8PZT composition, clearly implying that the MPB of this PMN-PZT system lies near the x = 0.2 composition. The grain size is about 1-3 μm judging by the scanning electronic microscope photographs of the fracture face. The temperature dependence of the dielectric constant illustrates that the Curie temperature descends linearly with the content of PMN increases. For x = 0.2, the maximum value of dielectric constant is 16380 at the Curie temperature of 308.8°C, and the piezoelectric constant is 351 pC/N.