Study on structure and properties of Pb(Sc1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 ternary ceramics near morphotropic phase boundary

Abstract

xPb(Sc1/2Nb1/2)O3–yPb(Mg1/3Nb2/3)O3–zPbTiO3 (xPSN–yPMN–zPT, x/y/z=5/61/34, 25/38/37, 45/14/41) ceramics with morphotropic phase boundary (MPB) were prepared by a modified two-step columbite precursor method. The structure and electrical properties of ceramics were investigated. X-ray diffraction shows a pure perovskite structure without any trace of second phase. All of the ceramics exhibit high density and homogeneous microstructure, indicating that the modified two-step columbite precursor method is very feasible to fabricate PSN–PMN–PT ceramics. With increasing the content of PSN, the Curie temperature TC and phase transition temperature of rhombohedral to tetragonal TR–T increased obviously. The optimal properties achieved in 25PSN–38PMN–37PT with piezoelectric coefficient d33=478pC/N, dielectric permittivity εmax=8338, planar electromechanical coupling kp=65.1%, and Curie temperature TC=192.2°C, respectively. Dielectric measurement shows that the PSN–PMN–PT ceramics near MPB display the relaxor-like characteristics.