Oppositely charged colloidal binary mixtures: a colloidal analog of the restricted primitive model

The equilibrium phase diagram of a colloidal system composed of 1:1 mixture of positive and negative particles with equal charge is studied by means of Monte Carlo simulations. The system is the colloidal analog of the restricted primitive model (RPM) for ionic fluids. A liquid-gas transition is fou...

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Published inThe Journal of chemical physics Vol. 121; no. 5; p. 2428
Main Authors Caballero, José B, Puertas, Antonio M, Fernández-Barbero, Antonio, de las Nieves, F Javier
Format Journal Article
LanguageEnglish
Published United States 01.08.2004
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Summary:The equilibrium phase diagram of a colloidal system composed of 1:1 mixture of positive and negative particles with equal charge is studied by means of Monte Carlo simulations. The system is the colloidal analog of the restricted primitive model (RPM) for ionic fluids. A liquid-gas transition is found in the low-temperature-low-density region, similar to the liquid-gas transition in the RPM. The fluid-crystal transition is also studied, and the liquid phase is shown to be stable in a narrow range of temperatures. In the liquid, the pair distribution function shows alternating layers of particles with opposite sign of charge surrounding every particle. In the vapor phase, clusters of particles are observed, again in agreement with the RPM. However, a decreasing distribution of clusters is obtained, instead of the discrimination between charged and neutral clusters found in the RPM.
ISSN:0021-9606
DOI:10.1063/1.1767995