title: Phase behaviour of deionized binary mixtures of charged colloidal spheres.
abstract: We review recent work on the phase behaviour of binary charged sphere mixtures as a function of particle concentration and composition. Both size ratios Γ and charge ratios Λ are varied over a wide range. Unlike the case for hard spheres, the long-ranged Coulomb interaction stabilizes the crystal phase at low particle concentrations and shifts the occurrence of amorphous solids to particle concentrations considerably larger than the freezing concentration. Depending on Γ and Λ, we observe upper azeotrope, spindle, lower azeotrope and eutectic types of phase diagrams, all known well from metal systems. Most solids are of body centred cubic structure. Occasionally stoichiometric compounds are formed at large particle concentrations. For very low Γ, entropic effects dominate and induce a fluid-fluid phase separation. Since for charged spheres the charge ratio Λ is also decisive for the type of phase diagram, future experiments with charge variable silica spheres are suggested.
authors.affiliation: Institut für Physik, Johannes Gutenberg Universität Mainz, Staudinger Weg 7, D-55128 Mainz, Germany.
authors.forename: Nina J
authors.initials: NJ
authors.lastname: Lorenz
authors.forename: Hans Joachim
authors.initials: HJ
authors.lastname: Schöpe
authors.forename: Holger
authors.initials: H
authors.lastname: Reiber
authors.forename: Thomas
authors.initials: T
authors.lastname: Palberg
authors.forename: Patrick
authors.initials: P
authors.lastname: Wette
authors.forename: Ina
authors.initials: I
authors.lastname: Klassen
authors.forename: Dirk
authors.initials: D
authors.lastname: Holland-Moritz
authors.forename: Dieter
authors.initials: D
authors.lastname: Herlach
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Okubo