Experimental applications of sodium‐containing alloys in molten alkali halides

Sodium‐bismuth alloys were used as reference electrodes in contact with molten alkali halides to establish sodium activities. Electronic conductivity versus sodium activity was obtained for molten sodium halides using such alloys (ã5 mol% Na) in polarization experiments. Results are presented for molten NaI. Also concentration versus activity data for Na in Na‐Bi alloys were determined as a function of composition (xNa: 0.01–0.15) and temperature (700–900°C) by using a simple coulometric titration technique. Sodium‐lead alloys (ã 8 mol% Na) were used to study the kinetics of the sodium electrode in molten NaCl using ac impedance spectroscopy combined with galvanostatic perturbation. Results from potential measurements between aluminium and a sodium alloy electrode performed in cryolite‐alumina melts to study the effects of electrolyte composition are also presented.