Line-tension-induced scenario of heterogeneous nucleation on a spherical substrate and in a spherical cavity

TL;DR

This paper investigates how line tension influences heterogeneous nucleation on spherical substrates and cavities, revealing conditions where nucleation favors spherical shapes or becomes barrier-less, impacting understanding of phase transitions.

Contribution

It introduces a detailed analysis of line tension effects on nucleation free energy, highlighting scenarios where spherical nuclei are favored or nucleation becomes athermal, extending classical nucleation theory.

Findings

Positive large line tension favors spherical nuclei over lens-shaped ones.

Negative large line tension leads to barrier-less, athermal nucleation.

Line tension effects can induce a drying transition in nucleation processes.

Abstract

Line-tension-induced {scenario of heterogeneous nucleation} is studied for a lens-shaped nucleus with a finite contact angle nucleated on a spherical substrate and on the bottom of the wall of a spherical cavity. The effect of line tension on the free energy of a critical nucleus can be separated from the usual volume term. By comparing the free energy of a lens-shaped critical nucleus of a finite contact angle with that of a spherical nucleus, we find that a spherical nucleus may have a lower free energy than a lens-shaped nucleus when the line tension is positive and large, which is similar to the drying transition predicted by Widom [B. Widom, J. Phys. Chem. {\bf 99} 2803 (1995)]. Then, the homogeneous nucleation rather than the heterogeneous nucleation will be favorable. Similarly, the free energy of a lens-shaped nucleus becomes negative when the line tension is negative and large. Then, the barrier-less nucleation with no thermal activation called athermal nucleation will be realized.