Shock growth of ice crystal near equilibrium melting pressure under dynamic compression

Crystal growth and morphological transitions are crucial for fundamental science and wide applications. Nevertheless, their mechanisms under local nonequilibrium growth condition are unclear due to severe interference of thermal and mass transports on the interplay between thermodynamic driving force and interface kinetics. Here, we reveal the origin of the pressure-induced 2D shock growth of ice VI crystal by using dynamic compression, in which a dimensional transition from 3D to 2D is observed. Unlike generally expected, the 2D shock growth occurs from 3D crystal edges rather than from its corners upon fast compression, even near equilibrium growth condition. This is due to similar interface structure to the crystal edge plane facilitating the fast interface kinetics under local nonequilibrium growth.

Crystal growth is governed by an interplay between macroscopic driving force and microscopic interface kinetics at the crystal–liquid interface. Unlike the local equilibrium growth condition, the interplay becomes blurred under local nonequilibrium, which raises many questions about the nature of diverse crystal growth and morphological transitions. Here, we systematically control the growth condition from local equilibrium to local nonequilibrium by using an advanced dynamic diamond anvil cell (dDAC) and generate anomalously fast growth of ice VI phase with a morphological transition from three- to two-dimension (3D to 2D), which is called a shock crystal growth. Unlike expected, the shock growth occurs from the edges of 3D crystal along the (112) crystal plane rather than its corners, which implies that the fast compression yields effectively large overpressure at the crystal–liquid interface, manifesting the local nonequilibrium condition. Molecular dynamics (MD) simulation reproduces the faster growth of the (112) plane than other planes upon applying large overpressure. Moreover, the MD study reveals that the 2D shock crystal growth originates from the similarity of the interface structure between water and the (112) crystal plane under the large overpressure. This study provides insight into crystal growth under dynamic compressions, which makes a bridge for the unknown behaviors of crystal growth between under static and dynamic pressure conditions.