Phase Transitions at high-pressure and structural description of the macroscopic ferroelectric properties of the Pb(Zr1−xTix)O3 solid solution

PbZr_1-x Ti_xO₃ (PZT) is an important class of ferroelectrics materials with the ABO₃ perovskite-type structure due to their exceptional dielectric and piezoelectric properties. It is well known that PZT ceramics and thin films are sensitive to the level of stress induced by both external elastic and electric fields which fundamentally modifies their physical properties. In order to improve the understanding of structure-properties relationship, Pb(Zr_1-x Ti_x)O₃ materials were investigated at high-pressure by X-ray and neutron diffraction. Upon increasing pressure a series of low-symmetry structures are identified for both Ti and Zr rich compositions and the high pressure behavior is consistent with a reduction and a rotation of the spontaneous polarization and the onset of octahedral tilting leading to unit cell doubling. To ameliorate the knowledge of the origin of exceptional piezoelectric properties of PZT materials with compositions at the morphotropic phase boundary (MPB), in situ structural picture of the ferroelectric properties as a function of the applied electric field is reported (data were obtained by synchrotron X-ray diffraction). Finally, the ferroelectric fatigue of PZT ceramics with composition close to the MPB was also investigated and the structural contribution to the fatigue was pointed out as a reduced degree of tetragonal-to-monoclinic transformation which accounts for the reduction of the piezoelectric/ferroelectric efficiency.