Substrate foreign atoms and ice nucleation activity

Abstract

The nucleation capability of a substrate particle depends on many factors like (a) lattice match and symmetry, (b) water solubility, (c) size of the particle, (d) polarizability, (e) hydrophobicity, (f) the surface charge, and (g) the number and strength of surface sites capable of absorbing water molecules. These include sites provided by foreign atoms or ions behaving like hydrophilic centers on a relatively hydrophobic surface. The expression for nucleation rate by a particle suspended in liquid is modified by incorporating the number of such sites. This is applied to the ice-water system and particles of AgI-AgBr-Cul solid solutions. From this the energy required for self-diffusion of water molecules on the water-ice interface is estimated taking into consideration the misfit strain energy also. The dependence of interfacial energy and the shape factor on the number of foreign atoms on the surface is discussed in the light of experimental results.