TheX-ray topographic image contrast of ferroelectric domain boundaries in triglycine sulphate crystals

The X-ray topographic image contrast of ferroelectric domain boundaries contained in the interior of a triglycine sulphate crystal of high quality has been investigated. Both stacking-fault fringes and direct image contrast have been observed in the boundary image. It is found that the model of the 180° domain wall previously presented by Malis and Gleiter (1976), in which they propose that there exists both a relative lateral shift between the lattices in the oppositely-polarized regions and a local deformation of the crystal in a volume of substantial thickness near the boundary plane, is found to satisfactorily account for the observed images. The local Bragg angle associated with the boundary deformation is found to have a maximum deviation of ∼2 × 10−6 rad for the 140 planes from the Bragg angle in the perfect crystal.