Predicting the outcome of the growth of binary solids far from equilibrium

TL;DR

This paper uses simulations to explore how binary solids grow far from equilibrium, revealing kinetic trapping phenomena and a predictable nonequilibrium composition linked to jammed dimer tilings.

Contribution

It introduces a simple lattice model to predict nonequilibrium growth outcomes and connects these to jammed dimer tilings, providing a new theoretical framework.

Findings

Kinetic trapping occurs across various growth conditions.

Nonequilibrium structures have a predictable composition.

Mapping to dimer tilings explains the robust stoichiometry.

Abstract

The growth of multicomponent structures in simulations and experiments often results in kinetically trapped, nonequilibrium objects. In such cases we have no general theoretical framework for predicting the outcome of the growth process. Here we use computer simulations to study the growth of two-component structures within a simple lattice model. We show that kinetic trapping happens for many choices of growth rate and inter-component interaction energies, and that qualitatively distinct kinds of kinetic trapping are found in different regions of parameter space. In a region in which the low-energy structure is an `antiferromagnet' or `checkerboard', we show that the grown nonequilibrium structure displays a component-type stoichiometry that is different to the equilibrium one but is insensitive to growth rate and solution conditions. This robust nonequilibrium stoichiometry can be predicted via a mapping to the jammed random tiling of dimers studied by Flory, a finding that suggests a way of making defined nonequilibrium structures in experiment.