Liquid-glass transition of water/salt mixtures

Abstract

Water is known to exhibit a number of anomalous behaviors and to be an exceptionally poor glass-former. However, both features are strongly affected by applying pressure or adding salt. This means that these two parameters have strong influence on physical factors controlling the unusual features of water. By using a water/salt mixture as a model system, we experimentally demonstrate that the glass-forming ability and the fragility of a water/salt mixture are closely related to its equilibrium phase diagram. The key to this link may be frustration between local ordering and global ordering toward the crystal. Relying on the same role of salt as pressure in water anomalies as a breaker of local tetrahedral order, we infer the behavior of water under pressure from that of a water/salt mixture. This scenario not only explains unusual behavior of water-type liquids such as water, Si and Ge under pressure, but also may provide a general explanation on the link between the equilibrium phase diagram, the glass-forming ability, and the fragility of various materials for a wide class of materials.