Synchrotron white-beam x-ray topography of ferroelectric domains in a BATiO₃single crystal

Ferroelectric domains and strains in a barium titanate (BaTiO₃) single crystal, grown by the top-seeded solution growth technique, have been investigated by synchrotron white-beam X-ray topography (SWBXT) and optical microscopy. Conventional radiation X-ray topography studies in this system had previously been hampered by the presence of internal strain fields which made it difficult to observe the overall domain structures. SWBXT was found to be more suitable for this kind of study, with the overall domain configuration in the (100) crystal plate being readily observed. Also the condition of ΔP*g = 0 is almost obeyed for the 90 a—a walls which are predominant in a thin crystal. The 90° a—c wall satisfied the invisibility criterion, leaving only residual strain images. Some curved images of 90° a-a walls were observed, which could be interpreted as resulting from the interference between the 90° a—a domain walls and the internal strain field.