Structural properties of colloidal suspensions

Structural properties of three- and two-dimensional colloids composed by hard spheres and/or by Yukawa particles, which can have different diameters and charges, are studied by solving the Ornstein-Zernike equation, together with Percus-Yevick, hypernetted chain and Rogers-Young approximations. From the partial radial distribution functions gij(r) the partial structure factors Sij(k) are determined, and with them the compressibility structure factor Sx(k), the measured structure factor SM(k) and the Bhatia-Thornton structure factors SNN(k), SNQ(k) and SQQ(k). As an effect of diameter and/or charge polydispersity on the structure of binary mixtures, the position and height of the main peak of SM(k), and its value at k = 0, change non-monotonously with the composition. In the case of binary mixtures of hard and Yukawa spheres the structure is given by two different scales. A liquid-solid phase transition induced by a change in the dimensionality was found for monodisperse systems.