Phase Transition Mechanisms in Cadmium Sulfide from X-ray Diffraction Comparisons of High-pressure Experiments and Molecular Dynamics Simulation*

We use simulated X-ray diffraction (XRD) from atomistic molecular dynamics simulations to interpret recent shock and ramp compression experiments carried out at the Dynamic Compression Sector at the Advanced Photon Source, and the Thor driver at Sandia National Labs.  Cadmium Sulfide (CdS) single crystal is a well-studied material which undergoes a stress-induced solid-solid phase transition from wurtzite to rock salt structures at a few GPa.  The time scales, and perhaps mechanisms, of this transition have been found to depend on the orientation of the compression wave relative to the initial crystal lattice (i.e. a-axis vs c-axis).  We use simulation to help separate XRD pattern contributions from multiple final orientation domains and use these orientations to distinguish between several possible Martensitic phase transition mechanisms.