Removing grain boundaries from three-dimensional colloidal crystals using active dopants

TL;DR

This study uses computer simulations to demonstrate that active colloids can effectively remove grain boundaries in 3D colloidal crystals by promoting boundary mobility and recrystallization, leading to larger single crystals.

Contribution

It introduces a novel method of using active dopants to eliminate grain boundaries in colloidal crystals, a process not previously demonstrated.

Findings

Active dopants gather at grain boundaries under sufficient self-propulsion.

Self-propulsion induces phase separation and boundary mobility.

No significant grain growth occurs without phase separation.

Abstract

Using computer simulations we explore how grain boundaries can be removed from three-dimensional colloidal crystals by doping with a small fraction of active colloids. We show that for sufficient self-propulsion, the system is driven into a crystal-fluid coexistence. In this phase separated regime, the active dopants become mobile and spontaneously gather at the grain boundaries. The resulting surface melting and recrystallization of domains result in the motion of the grain boundaries over time and lead to the formation of a large single crystal. However, when the self-propulsion is too low to cause a phase separation, we observe no significant enhancement of grain growth.