Electromotive Force Measurements in Molten Rb‐Bi Alloys with a Rubidium β″‐Alumina Electrolyte

A Rb‐β″‐alumina solid electrolyte was developed by the exchange of Na‐β″‐alumina in RbCl and was used in concentration cells to measure the activity of Rb in liquid Rb‐Bi alloys. Values of ΔG , Dgr;H , and Dgr;S are reported for the temperature range 600°883 K. All were highly negative, indicating strong interaction between Rb and Bi in the melt. The excess stability was found to have two peaks, one at the 1:1 composition and the second near the stoichiometric 3:1 ratio. Liquidus points on the phase diagram were measured over most of the composition range.