X-RAY TOPO-TOMOGRAPHY OF LARGE HPHT SYNTHETIC DIAMONDS

Extended defects in large synthetic diamonds grown at high pressures and high temperatures (HPHT) using thermal gradient method were studied by X-ray topo-tomography with a laboratory setup. It is shown that temperature and growth rate are the principal factors influencing crystalline quality of the diamonds. Synthesis at high temperatures and low rate allows growth of single crystals with low density of dislocations, stacking faults and microtwin lamellae. Annihilation kinetics of the extended defects during annealing at high pressure implies important role of vacancies diffusion. The annihilation of such defects leads to formation of perfect dislocations.