Abrupt grain boundary melting in ice

TL;DR

This paper investigates how impurities influence grain boundary melting in ice by extending interaction theories to include frequency-dependent forces, revealing conditions for abrupt melting transitions.

Contribution

It introduces a theoretical model incorporating retarded potential effects to explain impurity-dependent abrupt melting in ice grain boundaries.

Findings

Impurities can cause an abrupt reduction in grain boundary film thickness.

At high impurity levels, classical solutal effects dominate melting behavior.

Screening of Coulomb interactions can lead to sudden melting transitions.

Abstract

The effect of impurities on the grain boundary melting of ice is investigated through an extension of Derjaguin-Landau-Verwey-Overbeek theory, in which we include retarded potential effects in a calculation of the full frequency dependent van der Waals and Coulombic interactions within a grain boundary. At high dopant concentrations the classical solutal effect dominates the melting behavior. However, depending on the amount of impurity and the surface charge density, as temperature decreases, the attractive tail of the dispersion force interaction begins to compete effectively with the repulsive screened Coulomb interaction. This leads to a film-thickness/temperature curve that changes depending on the relative strengths of these interactions and exhibits a decrease in the film thickness with increasing impurity level. More striking is the fact that at very large film thicknesses, the repulsive Coulomb interaction can be effectively screened leading to an abrupt reduction to zero film thickness.