Dielectric relaxation in water adsorbed on ionic crystals

Abstract

At 0·9 Mc./sec., dielectric loss in water adsorbed on CaF₂, MgO, and KCl powders is observed when the coverage exceeds about 0·5. To some extent the isotherms at 0° for these adsorbents conform to the B.E.T. type II classification. With KCl, anomalous behaviour is attributed to surface dissolution during multilayer adsorption. A multilayer phase transition shown by peaks in the variation of loss with temperature is discussed. There is evidence to show that AgI may promote a more ordered multilayer structure. Dielectric loss generally increases with increasing frequency in the range investigated. The nature of the relaxation process is uncertain, although certain features can be interpreted qualitatively in terms of a Maxwell–Wagner mechanisms.