Depletion induced demixing in polydisperse mixtures of hard spheres

TL;DR

This paper demonstrates that in polydisperse hard sphere mixtures, the fluid phase becomes thermodynamically unstable due to size-dependent density decay, leading to large spheres crystallizing into multiple solid phases.

Contribution

It reveals the conditions under which the fluid phase of polydisperse hard spheres is unstable, highlighting the role of size-dependent density decay in phase separation.

Findings

Fluid phase instability depends on exponential decrease in large sphere density.

Large spheres tend to crystallize into multiple solid phases.

Thermodynamic instability is linked to polydispersity and size distribution.

Abstract

Polydisperse mixtures are those in which components with a whole range of sizes are present. It is shown that the fluid phase of polydisperse hard spheres is thermodynamically unstable unless the density of large spheres decreases at least exponentially as their size increases. The instability is with respect to the large spheres crystallising out into multiple solid phases.