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 and charge ratios are varied over a wide range. By contrast to 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 size- and charge ratios 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 concen-trations. For very low size ratios entropic effects dominate and induce a fluid-fluid phase separation. As for charged spheres also the charge ratio is decisive for the type of phase behaviour, future experiments with charge variable silica spheres are suggested.

21 pages, 11 figures, 2 tables

References in corpus (3)

• Electrostatic correlations: from Plasma to Biology
• Reentrant glass transition in a colloid-polymer mixture with depletion attractions
• Independent Ion Migration in Suspensions of Strongly Interacting Charged Colloidal Spheres

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• From Nuclei to Micro-Structure in Colloidal Crystallization: Investigating Intermediate Length Scales by Small Angle Laser Light Scattering
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• Peaked bulk crystal nucleation in charged sphere melts from salt concentration dependent crystallization experiments at very low metastability
• Formation of a transient amorphous solid in low density aqueous charged sphere suspensions