Aggregation of binary colloidal suspensions on attractive walls

The adsorption of colloidal particles from a suspension on a solid surface is of fundamental importance to many physical and biological systems. In this work, Brownian Dynamics simulations are performed to study the aggregation in a suspension of oppositely charged colloidal particles in the presence of an attractive wall. For sufficiently strong attractions, the wall alters the microstructure of the aggregates so that B2 (CsCl-type) structures are more likely obtained instead of B1 (NaCl-type) structures. The probability of forming either B1 or B2 crystallites depends also on the inverse interaction range κa . Suspensions with small κa are more likely to form B2 crystals than suspensions with larger κa , even if the energetic stability of the B2 phase decreases with decreasing κa . The mechanisms underlying this aggregation and crystallization behaviour are analyzed in detail. The adsorption of colloidal particles from a suspension on a solid surface is of fundamental importance to many physical and biological systems.