Experimental Phase Diagram of a Binary Colloidal Hard-Sphere Mixture with a Large Size Ratio

Abstract

We determined the phase diagram of a binary hard-sphere dispersion with size ratio 9.3. Phase separation into a fluid and a crystal of large spheres is observed. The fluid-solid binodal is determined by measurements of compositions of coexisting phases. The results agree qualitatively with recent theories, although the latter strongly overestimate the depletion activity of the smaller spheres. By fluorescent labeling we are able to measure the mobility of both particles separately. We found evidence for a new glassy phase in which only the small spheres are mobile.