Electromotive force study of lanthanum in liquid bismuth

The thermodynamics of lanthanum (La) dissolved in liquid bismuth (Bi) were determined by means of the electromotive force (EMF) measurement using a galvanic cell consisting of molten chloride and liquid bismuth at the temperature ranging from 723 K to 975 K. A considerable increase of the activity coefficient with temperature was observed for the La-Bi alloy. In addition, the activity coefficient increased slightly with the concentration of La. The values of the molar excess free energy of formation, the excess enthalpy, and the excess entropy of La dissolved in Bi were determined. The heat of formation of liquid La-Bi alloys (ΔHLa-BiM) was deduced from the measured activity coefficient. There is a linear dependence of experimental ΔHLa-BiM on the La concentration.