Shock induced phase transformations in SiC

Although the high-pressure phase diagram of silicon carbide (SiC) is relatively simple, the high-pressure phase transition from the ambient cubic zinc-blende (3C) or hexagonal wurtzite-like (2H, 4H, …) polymorphs to the high-pressure rock-salt B1 phase remains a subject of debate. In particular, there is a disagreement between static and dynamic shock compression experiments, which report a wide range of transition pressures. Therefore, exploring material transformations in the mixed-phase regime remains an outstanding challenge in high-pressure physics. We have developed a new simulation capability, enabled by a quantum-accurate machine learning interatomic potential for SiC, which has allowed us to perform foundational billion-atom molecular dynamics shock simulations of phase transformation in the SiC mixed-phase region. These MD simulations have helped design and execute dynamic compression experiments using the DiPOLE laser facility at EuXFEL. We discuss the atomic-scale mechanisms of phase transformation, which are significantly influenced by concurrent inelastic deformations, as derived from the joint analysis of experimental and simulation results.