Phase Transitions in 2:1 and 3:1 Hard-Core Model Electrolytes

Critical temperatures, [Formula presented], densities, [Formula presented], and coexistence curves for 2:1 and 3:1 hard-core model electrolytes have been found by fine-discretization Monte Carlo simulation. The size ratio of [Formula presented] and [Formula presented] ions strongly affects [Formula presented] and [Formula presented]; the trends contradict most current theories. Large multivalent ions screened by small monovalent counterions exhibit normal gas-liquid transitions of direct relevance to phase separation in charge-stabilized colloids. Conversely, extrapolation suggests the absence of such transitions for sufficiently small multivalent ions with large monovalent counterions.