Service interruption on Monday 11 July from 12:30 to 13:00: all the sites of the CCSD (HAL, EpiSciences, SciencesConf, AureHAL) will be inaccessible (network hardware connection).
Skip to Main content Skip to Navigation
Journal articles

Dielectric constant of ionic solutions: Combined effects of correlations and excluded volume

Abstract : The dielectric constant of ionic solutions is known to reduce with increasing ionic concentrations. However, the origin of this effect has not been thoroughly explored. In this paper we study two such possible sources: long-range Coulombic correlations and solvent excluded-volume. Correlations originate from fluctuations of the electrostatic potential beyond the mean-field Poisson-Boltzmann theory, evaluated by employing a field-theoretical loop expansion of the free energy. The solvent excluded-volume, on the other hand, stems from the finite ion size, accounted for via a lattice-gas model. We show that both correlations and excluded volume are required in order to capture the important features of the dielectric behavior. For highly polar solvents, such as water, the dielectric constant is given by the product of the solvent volume fraction and a concentration-dependent susceptibility per volume fraction. The available solvent volume decreases as function of ionic strength due the increasing volume fraction of ions. A similar decrease occurs for the susceptibility due to correlations between the ions and solvent, reducing the dielectric response even further. Our predictions for the dielectric constant fit well with experiments for a wide range of concentrations for different salts in different temperatures, using a single fit parameter related to the ion size.
Complete list of metadata

Cited literature [50 references]  Display  Hide  Download
Contributor : Emmanuelle De Laborderie Connect in order to contact the contributor
Submitted on : Thursday, August 27, 2020 - 4:37:11 PM
Last modification on : Tuesday, January 4, 2022 - 4:41:14 AM
Long-term archiving on: : Saturday, November 28, 2020 - 12:53:15 PM


Files produced by the author(s)



Ram M. Adar, Tomer Markovich, Amir Levy, Henri Orland, David Andelman. Dielectric constant of ionic solutions: Combined effects of correlations and excluded volume. Journal of Chemical Physics, American Institute of Physics, 2018, 149 (5), pp.054504. ⟨10.1063/1.5042235⟩. ⟨cea-02924068⟩



Record views


Files downloads