High-pressure phases in highly piezoelectric PbZr0.52Ti0.48O3

Two novel room-temperature phase transitions are observed, via synchrotron x-ray diffraction and Raman spectroscopy, in the PbZr0.52Ti0.48O3 alloy under hydrostatic pressures up to 16 GPa. A monoclinic (M)-to-rhombohedral (R-1) phase transition takes place around 2-3 GPa, while this R-1 phase transforms into another rhombohedral phase, R-2, at similar or equal to6-7 GPa. First-principles calculations assign the R3m and R3c symmetry to R-1 and R-2, respectively, and reveal that R-2 acts as a pressure-induced structural bridge between the polar R3m and a predicted antiferrodistortive R (3) over barc phase.