A generalized classical nucleation theory for rough interfaces: application in the analysis of homogeneous nucleation in silicate liquids

Abstract

Computer simulations as well as a recent in situ small-angle X-ray scattering study of the nucleation process have shown evidences in favor of the presence of atomic scale surface roughness of the nuclei, especially at low temperatures and/or at early stages of their development. In this article we have introduced a generalized version of the classical theory of homogeneous nucleation in order to incorporate the effect of finite surface roughness of the critical nuclei. The surface roughness has been taken into account by treating the surface of the nuclei as a self-similar fractal with a fractal dimension 3⩾ d s⩾2. The energetic consequences of the increased surface area due to its fractal character have been shown to be sufficient to explain the long-standing discrepancy between the experimentally observed temperature dependence of homogeneous nucleation rates and corresponding theoretical predictions based on classical theory. This rough-interface theory has been tested against the literature data on homogeneous nucleation of crystals in a number of glass-forming silicate liquids.