Kossel line analysis on crystallization in colloidal suspensions

The processes of crystallization in salt-free aqueous suspensions of highly-charged latex particles were observed by laser diffraction experiments for semi-dilute specimens of concentration 0.1–10 vol%. The Kossel diffraction patterns provide accurate three-dimensional information on the suspensions enabling the time evolution of the crystal structure to be recorded in detail. The results showed that the ordering formation evolved by way of the following intermediate processes: two-dimensional hep structure ← random layer structure ← layer structure with one sliding degree of freedom ← stacking disorder structure ← stacking structure with multivariant periodicity ← fcc structure with (111) twin ← normal fcc structure. For less concentrated suspensions (< 2 vol %), the phase transition proceeded further from the normal fcc structure to the normal bcc structure via the bcc twin structure with twin plane (112) or (112).