The Formation Kinetics of Detonation Nanodiamonds

We report experimental data on small angle X-ray scattering behind the detonation wave front in the high pressure zone, obtained using synchrotron radiation. A series of detonation experiments with ultradisperse diamond in oxygen and oxygen-free media have led us to the conclusion that diamond cannot be produced immediately behind the wave front. We believe that here there is a diamond-free zone and zones of diamond formation. Additional information on this region was derived from the electrical conductivity measurements. It was found that the time (as well as the site) of nanodiamond nucleation coincided with the beginning of unloading. The shock compression initiates the adamantan-diamond transition. These findings indicate that it is the C-H bonds, rather than the C-C bonds, which break up in the adamantan structure and that there is a fast diffusion of hydrogen through adamantan and explosives. A new model of detonation nanodiamond formation is suggested on the basis of our experimental results.