The glass–liquid transition of hyperquenched water

Abstract

Non-crystalline solid forms of water prepared by the usual two methods of vapour-deposition on a substrate1,2 and by compression of hexagonal ice in a piston cylinder apparatus at 77 K (refs 3,4) do not seem to undergo a glass–liquid transition on heating2,5–7. Neither of these two, or possibly three, non-crystalline forms seem to be interconvertible by a single thermodynamic path involving only temperature or pressure. Also, their molecular structures are thermodynamically discontinuous8, with the structure of bulk water above 273 K and of emulsified water in the supercooled state near 230 K (see also refs 2 and 9). It has been difficult, therefore, to resolve whether or not water supercools to a glassy state in a thermodynamically reversible manner. We now report the results of a calorimetric study of the glassy state of water obtained by rapid cooling or by hyperquenching, demonstrate the reversibility of its glass–liquid transition in the temperature range 113–148 K, and consider the implication to our understanding of its other non-crystalline solid forms.