Slow dynamics and dielectric relaxation in water/glycerol mixtures

Broadband dielectric spectroscopy (BDS) has been applied for studies of glass forming liquids, such as anhydrous glycerol and its mixtures with water. Usually, glycerol does not undergo crystallization. However, we showed that the BDS with a special protection of water absorption from air to the sample and a special temperature controlling can observe the crystallization while heating of anhydrous glycerol around 263 K and the melting at 293 K. In the case of a sample without the special protection of water absorption, the crystallization and the melting were not observed, and the sample remained in liquid, supercooled liquid or glassy states. These results indicate that very small amount of water absorption can change the dynamic structure of glycerol significantly and disables the crystallization. We also found non-Arrhenius behaviors of dc-conductivity and so called "excess wing" as well as the main relaxation process, and discussed changes of dielectric properties of water/glycerol mixtures with increase of water content.