LIQUID-LIKE BEHAVIOR IN COLLOIDAL CRYSTALS

The van der Waals approach to predict liquid-vapor coexistence, become s exact in the limit of weak, long-ranged attractive forces. However, for shorter-ranged am-actions, the liquid range shrinks and eventually disappears altogether. When the width of the attractive well becomes very small (less than 7% of the diameter of particles), an iso-structu ral solid-solid transition, reminiscent of the liquid-vapor transition , appears in the crystalline phase. This transition, that should be ex perimentally observable in certain colloidal suspensions, ends in a cr itical point. In quasi-two-dimensional systems (e.g. confined colloids ), this critical point induces the formation of a stable hexatic phase .