Anomalous temperature behavior in clay swelling due to ion-ion correlations

A. Thuresson, O. Karnland, B. Jönsson

Research output: Contribution to journalArticlepeer-review


We show, experimentally and theoretically, that swelling of both natural and refined clays has an anomalous temperature behavior depending on counterion valency. In an aqueous clay dispersion dominated by monovalent counterions the swelling pressure increases with temperature as expected from entropic arguments. In a clay with predominantly divalent counterions, the opposite behavior is found. The explanation is due to the fact that ion-ion correlations increase with temperature. Ion-ion correlations are important at strong electrostatic coupling and in an aqueous solution the dielectric permittivity, ϵr, drops with increased temperature, T, in such a way that the product ϵrT also decreases. Thus, the net effect is an increased coupling.

Original languageEnglish
Article number38002
JournalEurophysics Letters
Issue number3
Publication statusPublished - 2016 May 1

Subject classification (UKÄ)

  • Materials Chemistry


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