New Features of the Morphotropic Phase Boundary in the Pb(Zr1-xTix)O3 System

Recently a new monoclinic phase in the Pb(Zr1-xTix)O3 ceramic system has been reported for a composition of x=0.48. In this work, samples with Ti contents x=0.47 and 0.50, which are both tetragonal below their Curie point, have been investigated. In the sample with x=0.50, the tetragonal phase was found to transform to a monoclinic phase at about 200 K as the temperature was lowered. The sample with x=0.47 showed a complicated region of phase coexistence between ~ 440K-320K, becoming rhombohedral at around 300 K. No further symmetry change was found down to 20K. Dielectric measurements for these two samples are also reported. On the basis of these results, a preliminary phase diagram is presented. Optimum compositional homogeneity is needed to properly characterize the new monoclinic region