Surface Conductivity and Dielectrical Properties of Montmorillonite Gels*

R. A. Weiler and J. Chaussidon
Center of biological and Colloidal Soil Chemistry, Catholic University of Louvain, Louvain, Belgium
Centre National de la Recherche Agronomique, Versailles, France
* Based on the dissertation submitted by R. A. Weiler for the Ph.D. degree.

Abstract: The surface conductivity of salt free montmorillonite clay gels saturated with lithium, sodium, potassium and cesium has been studied. The theory of the behavior of heterogeneous dielectrics adapted to systems having a surface charge density has been applied to the clay gels. From numerical calculations it became evident that the value of the depolarization factor may be extrapolated to 1 in the direction of the small axis of the platelet, meaning that the field action is zero in this direction. Along the long axis, however, the action is complete and the motion of the charge carriers is essentially tangential to the platelet. The values of the surface conductance are of an order of magnitude of 10−9 Mho.

The investigation of the behavior of the water molecules has been carried out over a wide temperature range (145–320°K). At temperatures below 273°K, the conduction appears to be predominantly protonic; the counterions are considered to be disturbing elements in the water layer structures, thus creating a number of lattice defects able to transport the current. Above 273°K, the conduction is essentially due to the adsorbed cations, their contribution starts during the phase change.

Clays and Clay Minerals; July 1968 v. 16; no. 2; p. 147-155; DOI: 10.1346/CCMN.1968.0160205
© 1968, The Clay Minerals Society
Clay Minerals Society (www.clays.org)