Thermodynamic investigation of the ternary K–Pb–Sn and Rb–Pb–Sn alloys

Abstract

Activity coefficients for alkali metals in the K–Pb–Sn and Rb–Pb–Sn alloys were measured at 606 °C (879 K) for compositions generally less than about 10 at.% alkali metal. An alkali metal concentration cell with a potassium or rubidium substituted β-Al2O3 solid electrolyte was used to perform the experiments. A coulometric titration technique was used to electrochemically generate the alkali metal in the Pb–Sn alloys. The results indicated that, for both potassium and rubidium alloys, as solvent composition is varied from pure tin to pure lead the liquid becomes more associated, suggesting the formation of complex species. Key words: thermodynamics, alkali metals, liquid alloys.