Solidification and crystal growth of highly compressed hydrogen and deuterium: Time-resolved study under ramp compression in dynamic-diamond anvil cell

摘要

Solidification of hydrogen and deuterium has been studied under dynamic compression using dynamic-diamond anvil cell, time-resolved Raman spectroscopy, and fast micro-photography. Liquid H2 or D2 solidifies into a grain boundary free crystal grown from the outer edge of the sample chamber in 1–30 ms depending on the compression rate. The time scale of solidification agrees well with that of the discontinuous Raman shift across the liquid/solid phase boundary, underscoring a compression rate dependence of the solidification process. The crystal growth rates were measured to be 0.12–0.80 cm/s for H2 and 0.13–1.27 cm/s for D2, varying linearly with the compression rate.