X-Ray Topographic Study on Lattice Strain at 180° Domain Wall in Ferroelectric BaTiO3

Lattice strain at 180° domain walls in BaTiO 3 has been studied by X-ray topography for the case of a -plate in which the spontaneous polarization P s is parallel to the surface of the plate. At the 180° domain boundaries which were not parallel to P s , domain walls of 2 ∼3 µm thick with strained lattices were observed. Estimated lattice distortion was the shear strain of x 23 ≃1.6 ×10 -4 . The additional polarization normal to P s was estimated from the shear strain and the resultant polarization became nearly parallel to the boundary. The strained wall was not detected for the wall which was parallel to P s . Moiré fringes observed at the wedge-shaped domain boundary were well explained by the interference between the diffracted X-rays from two antiparallel domains having a strained domain wall between them.