Images of inclusions in synchrotron white-beam back-reflection X-ray topographs appeared as spots of light contrast surrounded by darker rings, resembling images of micropipes, which appeared as distinct white circles surrounded by dark rings. Sectional topographs taken across the centers of micropipes gave vertically displaced 2-tailed images, arising from the helical tilt of the reflecting planes about the micropipes' screw dislocation axes. Section topographs taken across the inclusions exhibited no vertical displacement, only dark bars bracketing a region of depleted contrast, arising from the convex bulge of the reflecting planes lying above the inclusion. The features of the inclusion images could be reproduced in computer simulations based on the elastic displacement function of a spherical inclusion in a semi-infinite solid, and compared with others based on the displacement function of a screw dislocation in an infinite solid.

The contrast of Inclusions Compared with that of Micropipes in Back-Reflection Synchrotron White-Beam Topographs of SiC. W.M.Vetter, M.Dudley: Journal of Applied Crystallography, 2004, 37[2], 200-3