Effect of Zr/Ti ratio on the properties of PMMN–PZT ceramics near the morphotropic phase boundary

Pb(Mg1/3Nb2/3)O3–Pb(Mn1/3Nb2/3)O3–Pb(ZrxTi1−x)O3 quaternary piezoelectric ceramics with varying Zr/Ti ratio, which locate in the vicinity of the morphotropic phase boundary (MPB), were prepared. The phase structure, the piezoelectric and dielectric properties of the system were investigated. X-ray diffraction patterns indicate that the MPB of the tetragonal and rhombohedral phase lies in the range 0.49<x<0.52. Both the piezoelectric coefficient (d33)/electromechanical coupling factor (Kp) and the dielectric constant (εr) reach the maximum values at x=0.50. The changes of resonant frequency with increasing Zr/Ti ratio are from a positive to a negative value and obtained a minimum value at x=0.50, which reflects the transition from tetragonal phase to rhombohedral phase.