Structure formation in binary colloids

TL;DR

This paper presents a theoretical analysis of structure formation in binary colloids, highlighting how particle concentration, composition, and dipole moments influence the resulting structures, from fractal aggregates to ordered lattices.

Contribution

It introduces a model considering only dipole-dipole interactions and combines molecular dynamics with analytic calculations to explain observed colloid structures.

Findings

Low concentration leads to fractal aggregation.

Increasing concentration results in lattice structures.

Model matches experimental observations.

Abstract

A theoretical study of the structure formation observed very recently [Phys. Rev. Lett. 90, 128303 (2003)] in binary colloids is presented. In our model solely the dipole-dipole interaction of the particles is considered, electrohidrodynamic effects are excluded. Based on molecular dynamics simulations and analytic calculations we show that the total concentration of the particles, the relative concentration and the relative dipole moment of the components determine the structure of the colloid. At low concentrations the kinetic aggregation of particles results in fractal structures which show a crossover behavior when increasing the concentration. At high concentration various lattice structures are obtained in a good agreement with experiments.