X-RAY TOPOGRAPHIC AND OPTICAL IMAGING STUDIES OF SYNTHETIC DIAMONDS

Large synthetic diamonds grown by the reconstitution method, all exhib iting the growth forms {100}, {111}, {110} and {113}, were studied. Cr ystal perfection was assessed by X-ray topography using a conventional source of Cu K alpha(1), radiation and employing the section, project ion and limited-projection topographic techniques. For the mapping of growth-sector configurations, cathodoluminescence topography, birefrin gence micrography and colouration mapping were also employed. Observat ions on three diamonds are detailed. Each specimen possessed a paralle l pair of mechanically polished surfaces, which had orientations +/-(1 00), +/-(111) and +/-(110), respectively. The overall widths and thick nesses of the three specimens were as follows: the +/-(100) faceted, 3 .2 and 0.76 mm; the +/-(111) faceted, 2.5 and 0.92 mm; the +/-(110) fa ceted, 5 and 0.7 mm. Dislocation densities and trajectories, and the w idths and contrast of individual dislocation images, are described. Th e variation of visibility of dislocation images in birefringence micro graphs and in X-ray topographs as a function of line orientation was i nvestigated. Other topics discussed include structure and contrast in X-ray topographic images of growth-sector boundaries and fine structur e in images of small inclusions and surface indentations.