title: Spatial variation of permittivity of an electrolyte solution in contact with a charged metal surface: a mini review.
abstract: Contact between a charged metal surface and an electrolyte implies a particular ion distribution near the charged surface, i.e. the electrical double layer. In this mini review, different mean-field models of relative (effective) permittivity are described within a simple lattice model, where the orientational ordering of water dipoles in the saturation regime is taken into account. The Langevin-Poisson-Boltzmann (LPB) model of spatial variation of the relative permittivity for point-like ions is described and compared to a more general Langevin-Bikerman (LB) model of spatial variation of permittivity for finite-sized ions. The Bikerman model and the Poisson-Boltzmann model are derived as limiting cases. It is shown that near the charged surface, the relative permittivity decreases due to depletion of water molecules (volume-excluded effect) and orientational ordering of water dipoles (saturation effect). At the end, the LPB and LB models are generalised by also taking into account the cavity field.
authors.affiliation: Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: E
authors.initials: E
authors.lastname: Gongadze
authors.forename: U
authors.initials: U
authors.lastname: van Rienen
authors.forename: V
authors.initials: V
authors.lastname: Kralj-Iglič
authors.forename: A
authors.initials: A
authors.lastname: Iglič
mesh_terms: D004560:Electricity; D004573:Electrolytes / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D008956:Models, Chemical; D013499:Surface Properties; D014867:Water
chemical_list: D004573:Electrolytes; D008670:Metals; D014867:Water