Discovery of microscopic tetragonal crystal structure of <001> oriented PMN-PT after quenching from a poled state

This paper presents evidence of a non-equilibrium phase transition for several PMN-32%PT and PMN-33/34%PT samples. The phase transition is produced by heating the samples to slightly above the rhombohedral-tetragonal transition temperature, TRT, and then rapidly quenching the sample to room temperature. Polarized microscopy results confirm that the elevated temperature and quenched crystal structures are the same, which indicates that the quenched state is tetragonal. This room temperature tetragonal state is indefinitely stable until a sufficiently high bias voltage is applied to the substrate at which point the traditional monoclinic phase is re-established. These room temperature tetragonal and monoclinic states show drastically different impedance resonance and dielectric values. Also, these results are shown to be highly repeatable over a number of samples of different PT composition provided from different manufacturers.