“…X-ray methods for the detection of dislocations in crystals are reviewed by Brummer (32). Observations of locally diffused regions in silicon wafers by the Berg-Barret method are described by Juleff and Wolfson (94) and a study of magnetic domains in terbium iron garnet was made by Basterfield and Prescott (19). High resolution topographic methods were used by Lang (113) to study lattice imperfections in many natural and man-made crystals and lattice imperfections in single crystals were observed directly by means of their contrast effects on an image of the crystal formed by a diffracted x-ray beam by Wallace (173).…”