Optimal Percolation of Disordered Segregated Composites

TL;DR

This paper investigates how segregation affects the percolation threshold in composite materials, revealing a non-monotonous relationship with an optimal segregation level that minimizes the critical concentration needed for percolation.

Contribution

It introduces a realistic model for segregated composites and identifies the existence of an optimal segregation level for percolation, which was not previously understood.

Findings

Percolation threshold is non-monotonous with segregation.

An optimal segregation level minimizes the critical concentration.

Competition between volume exclusion and concentration effects explains the phenomenon.

Abstract

We evaluate the percolation threshold values for a realistic model of continuum segregated systems, where random spherical inclusions forbid the percolating objects, modellized by hard-core spherical particles surrounded by penetrable shells, to occupy large regions inside the composite. We find that the percolation threshold is generally a non-monotonous function of segregation, and that an optimal (i. e., minimum) critical concentration exists well before maximum segregation is reached. We interpret this feature as originating from a competition between reduced available volume effects and enhanced concentrations needed to ensure percolation in the highly segregated regime. The relevance with existing segregated materials is discussed.