Crystal growth of organohectorite clay as revealed by atomic force microscopy

Noncontact atomic force microscopy, commonly referred to as ''tapping mode'' AFM, has been used to scan primarily the morphological features of growing hectorite clay crystallites synthesized in the presence of organoammonium cations. The use of such cations allows larger crystals to form in this system, making study by AFM feasible. This is the first time that temporal ''snapshots'' of a clay's nucleation and crystallization processes have been presented. The observed view does not support the perhaps predicted scene of small crystallites slowly ripening into large plates. Instead, larger aggregates appear to coalesce from numerous small crystallites that are closely associated in globular networks similar in appearance to ''strings of pearls'' at the initial stages of crystallization.