Demixing in binary mixtures of hard hyperspheres

The phase behavior of binary fluid mixtures of hard hyperspheres in four an d five dimensions is investigated. Spinodal instability is found by using a recent and accurate I,rescription for the equation of state of the mixture that requires the equation of state of the single component fluid as input . The role played by the dimensionality on the possible metastability of th e demixing transition with respect to a fluid-solid transition is discussed . The binodal curves in the pressure-chemical potential representation are seen to lie on a common line, independent of the size ratio.