Structures and partial clustering in binary mixtures of colloidal particles interacting via repulsive power law potentials

The hypernetted chain integral equation theory is used to study the structural behavior of two component mixtures of colloidal particles confined to a three dimensional box. The particles of the mixtures interact via a purely repulsive potential which scales as the nth power of the inverse of interparticle separation. We model the particles as point like and consider n to be 3, 5 and 7. It is shown that for all the three cases of n, the fluid phase remains macroscopically homogeneous and no phase separation takes place, but clustering of the smaller particles of the mixture occurs. This clustering of small particles is marked by the emergence of a prepeak which precedes the principal peak of their partial structure factor curve in the reciprocal space. We observe significant changes in the structural features of the mixtures with the variation in their characterizing parameters. The size of the clusters is shown to decrease as the value of n is increased but simultaneously they are becoming sharp having better defined boundaries. (C) 2014 Elsevier B.V. All rights reserved.