Crystal nucleation in a vapor deposited Lennard-Jones mixture

TL;DR

This study investigates vapor-deposited Lennard-Jones mixtures to understand crystallization pathways, revealing unique surface-promoted ordering and growth behaviors compared to quenched and bulk systems, with implications for industry and atmospheric science.

Contribution

It provides the first detailed comparison of nucleation in vapor-deposited, quenched, and bulk Lennard-Jones systems, highlighting surface effects and growth anisotropy.

Findings

Vapor-deposited layers show ordered domains due to faster surface relaxation.

Crystals nucleate homogeneously in a narrow temperature range across systems.

Nuclei grow initially isotropically, then favor basal plane growth.

Abstract

Understanding the pathways to crystallization during the deposition of a vapor phase on a cold solid substrate is of great interest in industry, e.g., for the realization of electronic devices made of crystallites-free glassy materials, as well as in the atmospheric science in relation to ice nucleation and growth in clouds. Here we numerically investigate the nucleation process during the deposition of a glassformer by using a Lennard-Jones mixture, and compare the properties of this nucleation process with both its quenched counterpart and the bulk system. We find that all three systems homogeneously nucleate crystals in a narrow range of temperatures. However, the deposited layer shows a peculiar formation of ordered domains, promoted by the faster relaxation dynamics toward the free surface even in an as-deposited state. In contrast, the formation of such domains in the other systems occurs only when the structures are fully relaxed by quenching. Furthermore, the nucleus initially grows in an isotropic symmetrical manner, but eventually shows sub-3D growth due to its preference to grow along the basal plane, irrespective of the layer production procedure.