Exclusion of impurity particles in charged colloidal crystals

Uniformly shaped, charged colloidal particles dispersed in water form ordered crystal structures when the interaction between the particles is sufficiently strong. Herein, we report the behavior of impurity particles, whose sizes and/or charge numbers are different from those of the bulk, on addition to the charged colloidal crystals. These impurities were excluded from the crystals during the homogeneous crystallization, crystal grain growth, and unidirectional crystallization processes. Such systems will be useful as models for studying the refinement of materials and crystal defects.