Dielectric Studies Deny Existence of Ultraviscous Fragile Water

The glass transition, a relaxation phenomenon, sets the low temperature limit to the liquid state. Glassy water that forms only under extreme quenching conditions is unstable against crystallization. Opinions differ on whether the glass transition can be observed at all. Here we measure the dielectric tan⁡δ for easily glassforming waterlike aqueous solutions, H₂O-H₂O₂ and H₂O-N₂H₄, to characterize the behavior of such systems during passage through their glass transitions. All show unambiguous T_g values of 136–140 K, the value generally assigned to pure water. However, the behavior of ε^′′/ε^′ is quite different from that in amorphous water in the same temperature range. Our findings eliminate "ultraviscous fragile liquid" as a possible description of water between 136 K and crystallization, but leave "ultraviscous stong liquid" a possibility to be considered.