Huge broadening of the crystal-fluid interface for sedimenting colloids

TL;DR

This study uses Brownian dynamics simulations to analyze how the crystal-fluid interface in sedimenting colloids broadens, revealing two distinct broadening mechanisms and a significant peak in interface width at specific gravitational strengths.

Contribution

It uncovers two types of interface broadening in sedimenting colloids and highlights a large, non-equilibrium peak in interface width related to gravitational driving.

Findings

Two types of interface broadening observed

Interface width peaks sharply at certain gravitational strengths

Significant non-equilibrium effects on interface structure

Abstract

For sedimenting colloidal hard spheres, the propagation and broadening of the crystal-fluid interface is studied by Brownian dynamics computer simulations of an initially homogeneous sample. Two different types of interface broadenings are observed: the first occurs during growth and is correlated with the interface velocity, the second is concomitant with the splitting of the crystal-fluid interface into the crystal-amorphous and amorphous-liquid interfaces. The latter width is strongly peaked as a function of the gravitational driving strength with a huge amplitude relative to its equilibrium counterpart.