Abrupt grain boundary melting in ice.

Area of Science:

• Physical Chemistry
• Materials Science
• Surface Science

Background:

• Grain boundary melting in ice is crucial for understanding its physical properties.
• The influence of impurities on phase transitions in condensed matter is a complex phenomenon.
• Classical theories often do not fully capture the interplay of forces at interfaces.

Purpose of the Study:

• To investigate the effect of impurities on the grain boundary melting of ice.
• To extend the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to include retarded potential effects.
• To analyze the competition between van der Waals and Coulombic interactions within ice grain boundaries.

Main Methods:

• Extension of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory.
• Inclusion of retarded potential effects in interaction calculations.
• Calculation of frequency-dependent van der Waals and Coulombic interactions at grain boundaries.

Main Results:

• At high impurity concentrations, classical solutal effects dominate ice melting.
• Dispersion forces compete with screened Coulombic interactions as temperature decreases, reducing film thickness with increasing impurity levels.
• At large film thicknesses, screened Coulombic repulsion can lead to an abrupt decrease in film thickness to zero.

Conclusions:

• Impurity concentration and surface charge density critically influence ice grain boundary melting behavior.
• The interplay between attractive dispersion forces and repulsive Coulombic interactions dictates melting dynamics.
• The study reveals a mechanism for abrupt melting in ice films due to impurity-induced screening effects.