Transition to a cubic phase with symmetry-breaking disorder in PbZr0.52Ti0.48O3 at high pressure

The tetragonal perovskite lead zirconate titanate PbZr0.52Ti0.48O3 ?PZT?, which is an important piezoelectric ceramic material, was found to undergo a phase transition to a cubic phase at close to 5 GPa by x-ray diffraction and Raman spectroscopy. Whereas the x-ray diffraction data indicated no deviation from cubic symmetry above this pressure, a strong Raman signal was present in this phase. The Raman spectrum obtained indicates the presence of symmetry-breaking disorder and is similar to those observed for ferroelectric relaxors. This result is in sharp contrast with the forbidden first-order Raman spectrum, which would be expected for a cubic paraelectric phase such as that observed at high temperature in this material.