Effect of Sodium Chloride on Internal Quasi-Liquid Layers in Ice Ih

We consider the effect of sodium chloride on the properties of internal interfaces in ice I-h. For this purpose, we employ molecular dynamics simulations to investigate the role of sodium and chloride ions in the properties of grain boundaries (GB), which are the interfacial regions separating adjacent crystal grains with different orientations. The results show that the presence of the ions significantly affects both the structural and dynamical characteristics of the disordered layers at the GB regions. Compared to pristine ice samples, in addition to reducing the degree of water structure, the ions enhance the mobility of the water molecules in the GB region. Even so, the briny GB regions display quasi-liquid behavior in that both the molecular and the ionic diffusivities are substantially lower than in the corresponding bulk liquid solutions at the same conditions of temperature, pressure, and salinity. Finally, the presence of sodium chloride in the GB regions is found to facilitate the GB sliding process, which is consistent with experimental insight.

Automated summary

The presence of sodium chloride significantly affects the properties of ice crystal grain boundaries by altering water molecule structure, increasing water molecule mobility, and reducing molecular and ionic diffusivities. Additionally, sodium chloride facilitates the grain boundary sliding process.