Homogeneous Crystal Nucleation in Droplets as a Method for Determining Line Tension of a Crystal-Liquid-Vapor Contact

The line tension of a three-phase contact is believed to play an important role in phase transition and phase equilibria in multiphase nanoscale systems, hence the need in developing various methods for its experimental evaluation. In this paper, we suggest an indirect experimental method for determining the line tension of a solid-liquid-vapor contact based on experiments on homogeneous crystallization of droplets. The underlying idea explores our recent finding that the line tension can give rise to an important contribution to the free energy of formation of a crystal nucleus in a surface-stimulated mode when one of its facets forms at the droplet surface and thus represents a “crystal-vapor” interface. The proposed method requires experimental data on the rate of homogeneous crystal nucleation as a function of droplet size. However, it can provide a rough estimate of line tension even if the rate is known only for one droplet size. Using the method to examine experimental data on homogeneous crystal nucleation in droplets of 19, 49, and 60 µm radii at T = 237 K, we evaluated the line tension of ice-(liquid) water-(water) vapor contact to be positive and of the order of 10^-11 N consistent with the current expectations.