Phase separation of asymmetric binary hard-sphere fluids.

On the basis of thermodynamically self-consistent integral equations for the pair structure it is shown that dense binary mixtures of hard spheres, of diameters ${\mathrm{\ensuremath{\sigma}}}_{1}$ and ${\mathrm{\ensuremath{\sigma}}}_{2}$, phase separate when the size ratio ${\mathrm{\ensuremath{\sigma}}}_{1}$/${\mathrm{\ensuremath{\sigma}}}_{2}$ is less than 0.2, and the partial packing fractions of the two species are comparable.