Nanoscale domain structures of 0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 around the morphotropic phase boundary

Abstract

We have investigated nanoscale domain structures of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 ((1-x)PMN-xPT) single crystal with x∼0.32 around a morphotropic phase boundary (MPB) by a transmission electron microscopy (TEM). We found domain structures with multiple inhomogeneities in the so-called monoclinic phase near the MPB region around x∼0.32 at room temperature. In addition to the large banded domains with the 100∼200 nm width, there exist nanoscale lamella-type domain structures with ∼10 nm width inside the large banded domains. In-situ TEM observation revealed that these nanoscale domain structures are inherent to the monoclinic phase. These domain structures with multiple inhomogeneities in the monoclinic phase should be responsible for the giant piezoelectric response to the external electric field.