X-ray topographic images of several dozen of diamonds were recorded before and after their use as anvils in a diamond anvil high-pressure cell. The aim was to understand better, and prevent, the breakage of diamond anvils when they were used in contact with a He sample. Helium was a good hydrostatic medium for very high pressure studies but many anvils were subject to He embrittlement. X-ray topographic observations suggested that He atoms entered the diamond anvil via a diffusion process enhanced by sub-surface strains and/or extended pre-existing defects and non-hydrostatic stress. These atoms then opened cracks during non-hydrostatic loading of the diamond anvil. The diamond anvils could be classified into 3 types, depending upon the nature of the defects. An associated criterion for the selection of stones resistant to He was proposed.

An X-ray Topographic Study of Diamond Anvils - Correlation between Defects and Helium Diffusion. A.Dewaele, P.Loubeyre, R.André, J.Härtwig: Journal of Applied Physics, 2006, 99[10], 104906 (5pp)