Crystallization in settling mixtures of colloidal spheres and plates

The behavior of mixtures of silica spheres and smaller silica-coated gibbsite plates is studied by means of confocal microscopy. Addition of plates slows down the crystallization of the settling spheres. Liquidlike microphases of the plates are found in the sediments of the spheres. It is argued that this is due to simultaneous sedimentation of the plates and spheres as well as depletion interaction between both species. Typical length scales in the sediments, derived from Fourier transforms of the confocal images, suggest there are still specific interactions present.