Thermodynamics of reaction of praseodymium with gallium–indium eutectic alloy

Thermodynamic properties of Ga–In eutectic alloys saturated with praseodymium were determined for the first time employing the electromotive force method. The equilibrium potentials of the Pr–In alloys saturated with praseodymium (8.7–12.1 mol.% Pr) and Pr–Ga–In alloys (containing 0.0012–6.71 mol.% Pr) were measured between 573–1073 K. Pr–In alloy containing solid PrIn3 with known thermodynamic properties was used as the reference electrode when measuring the potentials of ternary Pr–In–Ga alloys. Activity, partial and excessive thermodynamic functions of praseodymium in alloys with indium and Ga–In eutectic were calculated. Activity (a), activity coefficients (γ) and solubility (X) of praseodymium in the studied temperature range can be expressed by the following equations:lgaα−Pr(In) = 4.425 − 11965/T ± 0.026.lgаα−Pr(Ga–In) = 5.866 − 14766/T ± 0.190.lgγα−Pr(Ga–In) = 2.351 − 9996/T ± 0.39.lgХPr(Ga–In) = 3.515 − 4770/T ± 0.20.