Grain refinement and partitioning of impurities in the grain boundaries of a colloidal polycrystal

TL;DR

This study investigates how secondary nanoparticles influence grain boundary formation and impurity partitioning in colloidal polycrystals, revealing that grain size controls nanoparticle segregation efficiency.

Contribution

It demonstrates the ability to tune polycrystal texture via nanoparticle concentration and crystallization rate, and quantifies segregation behavior based on grain size.

Findings

Nanoparticles segregate in grain boundaries of colloidal polycrystals.

Texture tuning achieved by varying nanoparticle volume fraction and crystallization rate.

Segregation efficiency depends solely on grain size.

Abstract

We study the crystallization of a colloidal model system in presence of secondary nanoparticles acting as impurities. Using confocal microscopy, we show that the nanoparticles segregate in the grain boundaries of the colloidal polycrystal. We demonstrate that the texture of the polycrystal can be tuned by varying independently the nanoparticle volume fraction and the crystallization rate, and quantify our findings using standard models for the nucleation and growth of crystalline materials. Remarkably, we find that the efficiency of the segregation of the nanoparticles in the grain-boundaries is determined solely by the typical size of the crystalline grains.