ANTIPARALLEL FERROELECTRIC DOMAINS IN PHOTOREFRACTIVE BARIUM-TITANATEAND STRONTIUM BARIUM NIOBATE OBSERVED BY HIGH-RESOLUTION X-RAY-DIFFRACTION IMAGING

Antiparallel ferraelectric (180-deg) domains have been observed by hig h-resolution x-ray diffraction imaging in barium titanate and strontiu m barium niobate. This technique permits the imaging of domains in thi ck (1-mm) samples with high spatial resolution (1 mu m). These domains are visible in both Laue and Bragg geometry but only in those diffrac tion images for which the diffraction vector has some component along the [001] axis (optical axis). The origin of the domain contrast is ex plained in terms of the unit cell symmetry and a new coupled-mode view of the dynamical theory of x-ray diffraction. This model also permits determination of domain location relative to the sample surfaces thro ugh the analysis of the domain fringe contrast. (C) 1996 Optical Socie ty of America.