Transmission double–crystal synchrotron studies of synthetic diamond using the Haruta stereo–pairs technique

Abstract

The Haruta method of obtaining a stereoscopic effect by a small rotation about the diffraction vector was used for the first time in the case of synchrotron X–ray double–crystal topography. Double–crystal experiments were performed on a 1.5 x 4 x 4mm 3 slab cut from a cuboctahedral synthetic diamond in the arrangement where the asymmetric 220 diamond reflection was matched by the 331 reflection from a silicon monochromator selecting 1.0 A radiation. The double–crystal topographs provided intense contrast for dislocations, stacking faults, growth–sector boundaries and other defects, often accompanied by distinct interference fringes. The images were strongly angle dependent and appropriate Haruta pairs were matched from series taken at positions on the rocking curve separated by small increments. The pairs exhibited a good stereoscopic effect for most of the defects, and also for the cases of many interference fringes. The stereoscopic effects were also compared with those obtained in single–crystal Haruta pairs in exactly the same geometry. It was found that some fringes, associated with some growth–sector boundaries and stacking faults, did not, however, produce a good stereoscopic effect, but the fringes appeared visible on the exit surface. These various features were confirmed by simulation of the stereoscopic effects in computer–calculated images of dislocations and stacking faults.