Nanodomain structures with hierarchical inhomogeneities in PMN-PT

Nanometric domain configuration of (1-x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ ((1-x)PMN-xPT) single crystals in the monoclinic phase around a morphotropic phase boundary (MPB) has been examined thoroughly by means of a transmission electron microscopy (TEM). Domain structures with hierarchically inhomogeneous configuration were found in the monoclinic phase near the MPB region around x~0.32, which are characterized as the nanoscaled lamella-type domain structures with the ~10 nm width inside the macroscopic-sized banded domains with the 100~200 nm width. To elucidate formation processes of the domain structures with hierarchically inhomogeneous configuration, an in-situ TEM observation of changes of the domain structures in the temperature window between 298 K and 500 K was carried out. It is revealed that these nanoscaled lamella-type domain structures with the ~10 nm width appear inside the banded domains due to the tetragonal structure and are inherent to the monoclinic phase.