Abstract
Transmission electron microscopy studies of domain morphology in 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystals reveal complex arrangements of a variety of domains. In addition to mesoscopic domains, there are those that consist of two mutually perpendicular parallel tweeds whose widths are less than 10 nm. The parallel tweeds are separated by shear strain. The superposition of two perpendicular displacements produces the various domain configurations that include sharp tips, right-angle corners and S-shaped domain walls. It appears that the competing rhombohedral and cubic phases result in asymmetrical domains. The transformation from cubic to rhombohedral phase creates a morphotropic phase-boundary material with specific ferroelectric properties. An improper martensitic phase transformation model may be used to explain the observed domain configurations.