Thin colloidal crystals : a series of structural transitions

Abstract

We study thin layers of colloidal crystals made of polystyrene balls (1.1 μm diameter) in aqueous suspension. These thin layers are produced by confining colloidal crystals between two glass planes, which act as repulsive and perfectly smooth boundaries at colloidal scales. When the two planes form a wedge, a continuous passage from 2 to 3 dimensions is realized. Direct observation with an optical microscope reveals that this passage is characterized by a series of structural transitions consisting of changes in the number of layers and also in the structure of each layer