Ionic Conductivity in KCl and Its Dependence on Electrodes

It has been pointed out that the d.c. as well as a.c. conductivity measurements with alkali-halide crystals are liable to be affected by the nature of the electrode employed. In the present study, a number of electrode materials were examined in this regard, especially for use with KCl. Carbon electrodes prepared by vacuum deposition were found to be satisfactory in that (i) contamination from electrodes through thermal diffusion was undetectable at least microscopically, (ii) the measured conductivity showed reproducible changes when the specimen temperaure was varied, and (iii) the d.c. and a.c. conductivity values agreed with each other. Using the carbon electrodes, the dielectric constant of KCl in the kilocycle region was determined in the temperaure range 236°–522°C.