Nina J Lorenz et al 2009 J. Phys.: Condens. Matter 21 464116 doi:10.1088/0953-8984/21/46/464116
Nina J Lorenz1, Hans Joachim Schöpe1, Holger Reiber1, Thomas Palberg1, Patrick Wette2, Ina Klassen2, Dirk Holland-Moritz2, Dieter Herlach2 and Tsuneo Okubo3
Show affiliationsWe 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.
Soft matter, liquids and polymers
Issue 46 (18 November 2009)
Received 22 April 2009, in final form 23 July 2009
Published 27 October 2009
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