Bridging scales: from classical colloidal crystals to mesocrystals with modern X-ray synchrotron methods

This review explores different colloidal systems and their crystals as well as their special case namely - mesocrystals. First, we highlight recent advances in fabrication methods of colloidal crystals (mesocrystals) and then describe small-angle and ultra-small-angle X-ray scattering (SAXS and USAXS) from colloidal assemblies organized from particles of different shape. Here, we already introduce different types of defects that are present in colloidal crystals. Next, we go to a modern description of angular X-ray cross-correlation analysis (AXCCA) and its applications on colloidal and mesocrystalline materials. After that we discuss phase retrieval techniques, namely coherent X-ray diffraction imaging (CXDI) and ptychography, as emerging tools for structural characterization of colloidal crystals and mesocrystals. We conclude with perspectives on the opportunities that will be provided by the 4th generation synchrotron sources for studying colloidal crystals and mesocrystals.