Femtosecond X-ray Radiography of Shocked Diamond*

Understanding how materials deform at the highest strain rate of shock compression is necessary to accurately model and predict the behavior of materials under extreme conditions. Using the femtosecond-duration pulses generated by the SACLA x-ray free electron laser (XFEL), we performed in-situ x-ray radiography of single crystal diamonds shocked along three different crystal orientations of <100>, <110>, and <111>. By illuminating the sample perpendicular to the shock propagation direction, we visualized elastic and inelastic shock wavefronts propagating in the diamond at different velocities, followed by subsequent deformation bands appearing along the {111} planes. Based on comparison to the known {111} slip and possible phase transition in diamond, we interpret these results indicate the formation of stacking faults initiating the inelastic deformation.