Heterogeneous Nucleation near Metastable First-Order Bulk and Surface Phase Transitions

Abstract

Phase transformations such as freezing typically start with heterogeneous nucleation. Here the variation of the rate of heterogeneous nucleation of a new equilibrium phase is studied. The effect on this rate of crossing metastable bulk and surface first-order phase transitions is determined. There is partial but not complete wetting at the metastable bulk transition. The rate of nucleation of the new equilibrium phase changes discontinuously as the metastable transitions are crossed. These discontinuities can be large enough that on crossing a phase transition, the rate of nucleation can jump from a negligible value to an easily observable value; that is, the transformation from one metastable phase to another can trigger nucleation of the equilibrium phase. These findings are relevant to heterogeneous nucleation in liquid alkanes and possibly to that in solutions of some globular proteins.