This thesis presents an in-depth study on the effect of colloidal particle shape and formation mechanism on self-organization and the final crystal symmetries that can be achieved. It demonstrates how state-of-the-art X-ray diffraction techniques can be used to produce detailed characterizations of colloidal crystal structures prepared using different self-assembly techniques, and how smart systems can be used to investigate defect formation and diffusion in-situ. One of the most remarkable phenomena exhibited by concentrated suspensions of colloidal particles is the spontaneous self-organization into structures with long-range spatial and/or orientational orders. The study also reveals the subtle structural variations that arise by changing the particle shape from spherical to that of a rounded cube. In particular, the roundness of the cube corners, when combined with the self-organization pathway, convective assembly or sedimentation, was shown to influence the final crystal symmetries.

This book is a printed edition of the Special Issue "X-Ray Free-Electron Laser" that was published in Applied Sciences

Submicron-sized colloidal particles dispersed in a liquid medium self-assemble to form ordered “crystal” structures in which the particles are regularly arranged in body-centered or face-centered cubic lattice structures. Colloidal crystals have been useful models for studying crystallization in general. They have also attracted considerable attention as novel materials. In this chapter, we describe the physical basis and experimental studies of colloidal crystallization, in particular those of charged colloids. We first present a general introduction to the physical background on the stability and interaction of colloids. Then we report our studies on the crystallization of charged colloids, including charge-induced crystallization, unidirectional crystallization, gel immobilization, and exclusion of impurities. Finally, we review recent research topics in this field, including those on opal crystals and complex structures.