Mesoscopic theory for size- and charge- asymmetric ionic systems. I. Case of extreme asymmetry

Abstract

A mesoscopic theory for the primitive model of ionic systems is developed for arbitrary size, $\lambda ={\sigma }_{+}/{\sigma }_{-}$, and charge, $Z=e_{+}/|e_{-}|$, asymmetry. Our theory is an extension of the theory we developed earlier for the restricted primitive model. The case of extreme asymmetries $\lambda \to \infty$ and $Z\to \infty$ is studied in some detail in a mean-field approximation. The phase diagram and correlation functions are obtained in the asymptotic regime $\lambda \to \infty$ and $Z\to \infty$, and for infinite dilution of the larger ions (volume fraction $n_p\sim 1/Z$ or less). We find a coexistence between a very dilute 'gas' phase and a crystalline phase in which the macroions form a bcc structure with the lattice constant $\approx 3.6{\sigma }_{+}$. Such coexistence was observed experimentally in deionized aqueous solutions of highly charged colloidal particles.

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Cited by in corpus (11)

• Density functional theory for soft matter with mesoscopic length scale fluctuations included within field-theoretic formalism
• Mesoscopic theory for inhomogeneous mixtures
• Field theory for size- and charge asymmetric primitive model of electrolytes. Mean-field stability analysis and pretransitional effects
• Effect of mesoscopic fluctuations on equation of state in cluster-forming systems
• Field-theoretic description of ionic crystallization in the restricted primitive model
• Correct scaling of the correlation length from a theory for concentrated electrolytes
• Correlation functions in ionic liquid at coexistence with ionic crystal. Results of the Brazovskii-type field theory
• Universality class of the critical point in the restricted primitive model of ionic systems
• Spatial inhomogeneities in ionic liquids, charged proteins and charge stabilized colloids from collective variables theory
• Self-consistent theory for inhomogeneous systems with mesoscopic fluctuations
• Correlation functions in mixtures with energetically favoured nearest-neighbours of different kind: a size-asymmetric case