  When a particle is placed in a material with a lower bulk melting
temperature, intermolecular forces can lead to the existence of a premelted
liquid film of the lower melting temperature material. Despite the system being
below the melting temperatures of both solids, the liquid film is a consequence
of thermodynamic equilibrium, controlled by intermolecular, ionic and other
interactions. An imposed temperature gradient drives the translation of the
particle by a process of melting and refreezing known as thermal regelation. We
calculate the rate of regelation of spherical particles surrounded by premelted
films that contain ionic impurities. The impurities enhance the rate of motion
thereby influencing the dynamics of single particles and distributions of
particles, which we describe in addition to the consequences in natural and
technological settings.
