Probing the Metastability Limit of Liquid Water under Dynamic Compression

Kinetics can play an important role in the transformation of materials to different high-pressure phases on the short time scales associated with dynamic-compression experiments. The study of phase-transition kinetics has motivated many theoretical and experimental works on the rapid freezing of liquid water into the ice-VII phase. We present measurements of the over-pressurization of the water-ice VII phase transition at 10x higher compression rates than previously studied. Water was ramp compressed to peak pressures of $\sim$15 GPa over $\sim$10 ns at the Omega laser facility. The pressure at which water froze into the ice VII phase is deduced from wave-profile measurements and compared to predictions using a phase-transition-kinetics model recently developed at Lawrence Livermore National Laboratory.