Separation and fractionation of order and disorder in highly polydisperse systems

TL;DR

This study uses Monte Carlo simulations to investigate phase separation in highly polydisperse liquids and colloids, revealing a segregation into crystalline and disordered phases during solidification.

Contribution

It demonstrates the separation of ordered and disordered regions in highly polydisperse systems through large-scale simulations, highlighting the fractionation process.

Findings

Identification of phase separation into crystalline and disordered phases

Evidence of size-dependent segregation in the solid phase

Observation of fractionation during solidification process

Abstract

Microcanonical Monte Carlo simulations of a polydisperse soft-spheres model for liquids and colloids have been performed for very large polydispersity, in the region where a phase-separation is known to occur when the system (or part of it) solidifies. By studying samples of different sizes, from N=256 to N=864, we focus on the nature of the two distinct coexisting phases. Measurements of crystalline order in particles of different size reveal that the solid phase segregates between a crystalline solid with cubic symmetry and a disordered phase. This phenomenon is termed fractionation.