Thermodynamic properties of liquid silver–antimony alloys determined from emf measurements

Abstract

The thermodynamic properties of the liquid Ag–Sb alloys were determined using solid oxide galvanic cells with zirconia electrolyte. The emfs of the cells: Ag x Sb (1−x), Sb 2 O 3/ O 2−/ air were measured in the temperatures range 950–1100 K in the whole range of the alloy compositions. First, the Gibbs free energy of formation of liquid Sb 2O 3 from pure elements was derived: ΔG° f( Sb 2 O 3) ( J/ mol)=−687100+243.23T. Next, the activities of antimony were measured as a function of the alloy compositions, x. Redlich–Kister polynomial expansion was used to describe the thermodynamic properties of the liquid phase. From the model equations the limiting value of the logarithm of activity coefficient of antimony in silver was obtained as a function of temperature: ln γ Sb 0=−3812.5/T+0.4112. The obtained results were compared with the experimental values reported in the literature.