Contrast of Ferroelastic and Ferroelectric Domains in White-Beam X-ray Topographs

White-beam synchrotron topography has been demonstrated to be well suited for observation of all kinds of ferroelastic and ferroelectric twin domains. It is found that the domains that are misorientated against each other always appear as orientation contrasts in the topographs, while the antiparallel domains with parallel lattices may show different diffraction intensity by the synchrotron-radiation anomalous-scattering effect. Based on the reciprocal-lattice splitting and the diffraction geometry, a general method of determination of the image displacement associated with two misorientated domains is given to explain their orientation contrast. It is also revealed that the anomalous-scattering contrast of antiparallel domains arises from the anomalous-dispersion terms of the noncentrosymmetric atoms in the unit cell of ferroelectric crystals.