CALORIMETRIC STUDY OF PRESSURE-AMORPHIZED CUBIC ICE

High pressures can collapse a crystal to an amorphous solid whose properties differ from those of a vitrified solid. Here we report the thermal behavior of a high-density amorphous solid water produced by compression of cubic ice (which has no melting curve) up to 18 kbar. On heating, a rearrangement of H-bonds converts it to a structure with a glass → liquid transition temperature 6 K lower than that of glassy water. These have implications for our understanding of water's structures and are first observations of an amorphous solid transforming back to the same metastable crystal state from which it was prepared. © 1990 American Chemical Society.