Shock compression of diamond crystal

Two shock wave experiments employing inclined mirrors have been carried out to determine the Hugoniot elastic limit (HEL), final shock state at 191 and 217 GPa, and the post-shock state of diamond crystal, which is shock-compressed along the intermediate direction between the <111> and <110> crystallographic axes. The HEL wave has a velocity of 19.9 ± 0.3 mm/µsec and an amplitude of 63 ± 28 GPa. An alternate interpretation of the inclined wedge mirror streak record suggests a ramp precursor wave and then another HEL value. The maximum post-shock density achieved upon release from the ∼200 GPa shock state is ∼3.95 Mg/m³, which compares to the initial density 3.52 Mg/m³. This result suggests an elastic unloading effect or shock-induced transition to a denser (possibly metallic) phase.