The morphotropic composition of lead zirconate titanate ͑PZT͒, PbZr 0.52 Ti 0.48 O 3 , was studied as a function of temperature ͑47-310 K͒ and hydrostatic pressure ͑from 0.1 MPa to 7.6 GPa͒ by neutron powder diffraction. Series of monoclinic ͑space groups Cm and Cc͒ and triclinic phases ͑space groups F1 and F1͒ were observed at various points in the P-T phase diagram of PbZr 0.52 Ti 0.48 O 3 . The high-pressure behavior is characterized by two mechanisms, a rotation and reduction of the spontaneous polarization and the onset of octahedral tilting leading to unit cell doubling. The results show that pressure, as in the case of temperature and external electric fields, can induce polarization rotation.

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Fatigue rates in the Pb(Zn1/3Nb2/3)O3–PbTiO3 perovskite solid solution were investigated for different compositions in the rhombohedral and tetragonal phases in a variety of directions, at various field levels. It was found that the fatigue rates depend on both the ferroelectric phase and crystallographic orientation. In the rhombohedral phase when the field is applied along the [001]C direction (where the direction is given in terms of the cubic prototype), excellent fatigue resistance was obtained.