REENTRANT PHASE-TRANSITION IN CHARGED COLLOIDAL SUSPENSIONS - A MONTE-CARLO STUDY

Monte Carlo simulations of aqueous charged colloidal suspensions interacting via an effective pair potential are carried out with a view to elucidate the mechanism of the reentrant phase transition reported in these systems. The computed pair-correlation functions show that a weakly interacting homogeneous suspension phase separates into dense and rare phases and thereafter reenters into a homogeneous state with crystalline or liquidlike order when the concentration of the ionic impurities is decreased. The cluster-size distribution indeed shows the existence of dense-phase droplets for the intermediate range of impurity-ion concentrations where the phase separation occurs. Some of the recent experimental results are discussed in the light of the present simulation results.