Studies of Individual Dislocations in Crystals by X-Ray Diffraction Microradiography

Abstract

The distribution of imperfections within the interior of crystals has been studied using ``projection topographs'' which are x‐ray diffraction images showing a projection of a slice of crystal and the imperfections in it. Individual dislocations have been observed in single crystals of diamond, silicon, germanium, lithium fluoride, sodium chloride, silver chloride, magnesium oxide, calcite, quartz, and aluminum. From the variation of dislocation contrast with the orientation of the x‐ray reflecting plane the direction of Burgers vector can be found. Dislocations can be seen with good contrast when the product of linear absorption coefficient μ and slice thickness t is of the order of unity or less. If μt≫1 the contrast is reversed through the Borrmann effect. Stereo pairs of projection topographs can be prepared from the pair of reflections hkl and h̄k̄l̄.