The piezoelectric and dielectric properties of PZT–PMN–PZN

The dielectric and piezoelectric properties of Pb0.96Sr0.04[(Zr1−yTiy)0.74 (Mg1/3Nb2/3)0.20(Zn1/3Nb2/3)0.06]O3 were investigated in the composition range 0.47≤y≤0.57. The piezoelectric ceramic system of PbTiO3–PbZrO3–Pb(Mg1/3Nb2/3)O3–Pb(Zn1/3Nb2/3)O3 with composition close to the morphotropic phase boundary was studied. Results of XRD and piezoelectric measurement indicated that the y=0.51 composition corresponds to morphotropic phase boundary (MPB) between tetragonal and pseudocubic perovskite. Owing to the phase coexistence at the phase boundary, there exists a different symmetry regions (DSR) near the MPB. The DSR boundary motion increases the dielectric permittivity and piezoelectric coefficients. The planar coupling factor and piezoelectric constant are higher for compositions near the MPB, but longitudinal velocity are lowest. The reason for the decrease of the velocity at the phase boundary is considered as the existence of the DSR. Owing to the DSR comprising the tetragonal phase and the pseudocubic phase, the interphase boundaries make the extra scattering of the velocity comparing to other composition. As far as the dielectric constant of poled material is concerned, its maximum in the multicomponent system is displaced into the tetragonal phase and does not coincide with the maximum of planar coupling factor. The variation of the remanent polarization with composition is the same as that of the coupling factor.