Carbon Condensation During High Explosive Detonations: Traversing the Carbon Phase Diagram by Varying Material and Detonation Geometry*

Explosive detonations produce a variety of different carbon nanomaterials that include detonation nanodiamond, carbon onions and other graphitic or amorphous phases. Understanding how these different nano-polymorphs form has challenged the scientific community. In this study, we varied the high-explosive material and the detonation geometry (i.e., cylindrical charge initiated at one end, vs. initiated at both ends) to change the temperatures and pressures attained during detonation and therefore the carbon nano-condensate phase and morphology. A characterization of these nanoscale phases, during detonation, was performed using synchrotron X-rays, as well as ex-situ TEM imaging and theoretical simulations. Due to the rapid detonation velocities ( ~ 8 mm/μs), the X-ray approach pushes the limits of synchrotron experimentation and requires careful considerations and challenges that are also presented. We compare our results of generated carbon morphologies to the heat of detonation and the detonation geometry of different high-explosive materials.