Thermodynamic properties of silver–palladium alloys determined by a solid state electrochemical method

Silver–palladium alloys have various industrial applications, such as in hydrogen permeation and hydrogen storage materials. The objective of the present study is to determine experimentally the thermodynamic properties of solid state silver–palladium alloys in low temperatures. Thermodynamic measurements of silver–palladium alloys have been performed over a temperature range of 450–750 K by the electromotive force method with superionic conductor AgI as the solid electrolyte. The activity and partial molar Gibbs energy of silver were obtained for Ag–Pd alloys over the whole composition range, and the thermodynamic properties of palladium were calculated using the Gibbs–Duhem equation. The results show that activities of silver exhibit fairly large negative deviations over most of the composition range, and the activities of palladium are characterized by both negative and positive deviations from the ideal Raoultian behavior. The results also show the minimum integral enthalpy of mixing of Ag–Pd alloys to locate at around 60 at.% Ag.