In situ observations of the self-assembling process of colloidal crystalline arrays

Growth processes of colloidal crystalline arrays in a fluidic glass cell were observed in situ by confocal laser scanning microscopy. The results showed that the growth direction varied with the growth rate. At an extremely low growth rate, the array grew toward the [112] direction of the face-centered-cubic lattice. At a moderate growth rate, it grew toward the [110] direction. However, an extremely high growth rate induced random arrays of the spheres. Moreover, we were able to visualize the generation and/or annihilation processes of several kinds of defects. The variation of the growth direction with the growth rate is discussed in terms of the difference in water-flow resistance in the crystalline arrays.