The split in the second peak in the structure factor of binary colloidal suspensions: glass-like order

Abstract

Structure factors of dilute binary colloidal suspensions of various compositions, particle diameter ratios and ionic impurity concentrations are investigated using polarised light scattering. For the first time, a split in the second peak of the measured structure factor is observed, suggesting the existence of glass-like order in the binary suspensions. The near-forward-scattered intensity from the colloidal suspension exhibiting a split second peak fluctuates much more slowly than that from the liquid-like ordered phase, corroborating the existence of glass-like order in the binary mixtures. The time evolution of the structure indicates that a liquid-like order continuously evolves into glass-like order as the strength of inter-particle interaction is increased by reducing the impurity concentration. The glass-like order is unstable towards formation of the crystalline state above a critical volume fraction (which depends on the impurity concentration) of the particles.