Hard core Yukawa fluid with temperature and density dependent interaction: Phase diagram of the AOT/water/decane microemulsion

A fluid with an interaction potential consisting of a hard core and an attractive Yukawa tail is considered. The strength of the attraction is taken to depend both on density and temperature in order to take into account the state dependence of the effective interaction suggested by the analysis of structural data of several colloidal suspensions, in particular microemulsions of AOT reverse micelles. The thermodynamics of this fluid is investigated starting from the inverse temperature expansion of the free energy in the mean spherical approximation. The temperature and density dependence of the interaction is incorporated in consistent expressions for the pressure, isothermal compressibility, and chemical potential. The phase diagram predicted by this method is in agreement with experimental data on AOT reverse micelles analyzed in the effective one component approach. (C) 1999 American Institute of Physics. [S0021-9606(99)72227-0].