Ice Nucleation in Periodic Arrays of Spherical Nanocages

A silicious material containing massive array of spherical nanocages connected to each other by small micropores was used to study ice nucleation in confined water under conditions of well-defined pore geometry. By purposefully selecting small size of the interconnecting pores below 2 nm, ice nucleation and growth were limited to occur only within the nanocages. By exploitation of nuclear magnetic resonance, ice nucleation rates at different temperatures were accurately measured. These rates were obtained to be substantially higher than those typically observed for micrometer-sized water droplets in air. In addition, the occurrence of correlations between ice nucleation in one nanocage with the phase state in the adjacent cages were observed. These results have important implication for a deeper understanding of ice nucleation, especially in confined geometries.