Superlattice formation in binary mixtures of hard-sphere colloids

Abstract

Binary mixtures of suspended hard-sphere colloidal particles, radius ratio ${\mathit{R}}_{\mathit{B}}$/${\mathit{R}}_{\mathit{A}}$=0.58, were observed to undergo entropically driven freezing transitions into both the ${\mathit{AB}}_2$ and the ${\mathit{AB}}_{13}$ superlattice structures at different relative proportions of the two species. The structures were identified by powder light crystallography and by electron microscopy of the dried solid phases. An approximate (constant volume) phase diagram containing three eutectics was determined. The results are compared with earlier work at size ratio 0.62.