Molten salt EMF cell measurements on U–Ga alloys

The Gibbs free energies of formation of UGa3, UGa2 and U2Ga3 were determined by using high temperature molten salt galvanic cell measurements. Three cells were assembled and EMFs were measured. The typical cell is as follows: U(s)//UCl3 in LiCl–KCl (eutectic)(l)//U–Ga (two phase alloy), where pure uranium is used as one of the electrodes and the other electrode is a two phase U–Ga alloy. The two phase alloys used as the electrodes in the cells I, II and III were 〈UGa3〉+{Ga},〈UGa3〉+〈UGa2〉 and 〈UGa2〉+〈U2Ga3〉, respectively. The Gibbs free energy of formation of UGa3, UGa2 and U2Ga3 with respect to α-uranium and liquid gallium in the temperature range 644–988, 751–947 and 800–950 K were determined to be −44.1+0.016T, −46.0+0.017T and −46.3+0.017T kJ gatom−1, respectively. The partial molar excess Gibbs free energy of uranium in liquid gallium at 816 K was determined to be −75.5±1.8 kJ gatom−1 and the partial molar enthalpy of uranium in liquid gallium in the saturated solution at 816 K to be −103.2±1.8 kJ gatom−1.