Colloidal hard-sphere crystallization kinetics in microgravity and normal gravity

The hard-sphere disorder-order transition serves as the paradigm for crysta llization. We used time-resolved Bragg light scattering from the close-pack ed planes to measure the kinetics of nucleation and growth of colloidal har d-sphere crystals. The effects of gravity are revealed by comparison of the experiments in microgravity and normal gravity. Crystallites grow faster a nd larger in microgravity, and the coarsening between crystallites is suppr essed by gravity. The face-centered-cubic structure was strongly indicated as being the stable structure for hard-sphere crystals. For a sample with a volume fraction of 0.552, the classic nucleation and growth picture is fol lowed. (C) 2001 Optical Society of America.