Structure of Binary Liquid Mixtures. I

An exact solution of the Percus-Yevick equation for the correlation functions Cᵢⱼ(r) appropriate to a binary mixture has been given by Lebowitz. We show that the Fourier transforms Cᵢⱼ(K) lead directly to the structure factors Sᵢⱼ(K), the latter being functions of a total packing parameter η, the ratio of the hardsphere diameters and the concentration parameter x describing the relative amount of each component in the mixture. An expression for the compressibility is also given. The results are applied to a discussion of x-ray scattering from mixtures.