Piezoelectric properties of (Pb, Sr) (Zr, Ti, Mn, Zn, Nb)O3 piezoelectric ceramic

Abstract

In this paper, the aim is to study the piezoelectric properties of (Pb, Sr)[(Zr, Ti)(Zn1/3Nb2/3) (Mn1/3Nb2/3)]O3 ceramic with compositions close to the morphotropic phase boundary. The dielectric and piezoelectric properties of this system were investigated by way of changed contents of two main compounds, TiO2 and Mn1/3Nb2/3. There are two phases existing in this system, one tetragonal and the other pseudocubic. With a constant amount of 4 mol% Pb(Mn1/3Nb2/3)O3 and 8 mol% Pb(Zn1/3Nb2/3)O3, the morphotropic phase boundary exists when the amount of PbTiO3 is nearly equal to 44 mol%. The structure is perovskite with pseudocubic symmetry for PbTiO3 less than 44 mol%, but it is tetragonal symmetry for higher PbTiO3 concentrations. The planar coupling factor and piezoelectric constant are higher for compositions near the morphotropic phase boundary, but the mechanical quality factor and longitudinal velocity are lowest. 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 electromechanical quality factor. The variation of remanent polarization with composition is the same as that of the coupling factor. Thus, compositions with the tetragonal phase are “ferroelectrically harder” and those with the pseudocubic phase are “ferroelectrically softer” than compositions close to the morphotropic phase boundary. Besides the influence of Ti, the effect of Mn1/3Nb2/3 is also studied in this paper. The planar coupling factor increases with increasing Mn1/3Nb2/3 and reaches a maximum at 5 mol% Mn1/3Nb2/3, and then decreases for higher Mn1/3Nb2/3 values. The mechanical quality factor increases, but the dielectric constant decreases, with increasing Mn1/3Nb2/3.