Capacitance and Impedance of Rhenium in Molten Alkali Metal Chlorides

Abstract

The electrode capacitance is determined as a function of potential by measuring the capacitance and the impedance of a rhenium electrode in NaCl, KCl, and CsCl melts at various temperatures and ac signal frequencies, and the impedance parameters are calculated. The capacitance curve is shown to have two minima in these systems and an additional third minimum in sodium and potassium chlorides. This third minimum disappears when temperature increases. The potential of the cathode minimum of capacitance measured at an ac signal frequency of about 10³ Hz coincides with the corresponding minimum of the capacitance of the double electrical layer. The potentials of the central and anode minima of capacitance measured at a frequency of about 1 Hz coincide with the potentials of the minima of adsorption capacitance.