Gibbs energies of formation of the intermetallic compounds of U–Sn system

Gibbs energies of formation of the intermetallic compounds, USn3, U3Sn7, USn2, and USn were determined by using high temperature molten salt galvanic cells: U(s)//UCl3 in LiCl–KCl (eutectic)//U–Sn alloy, where pure uranium was used as one of the electrodes and a two phase alloy of uranium and tin as the other. The two phase alloys used in cells I, II, III and IV as the electrodes were 〈USn3〉 + {Sn}, 〈U3Sn7 + USn3〉,〈USn2 + U3Sn7〉 and 〈USn + USn2〉, respectively. The Gibbs energies of formation (ΔfG0ΔfG0) of USn3, U3Sn7, USn2 and USn with respect to α-U and liquid Sn, in the temperature range 682–905 K, were determined to be given by ΔfG0(USn3)(kJmol-1)=-172.8+0.061T(K),ΔfG0(U3Sn7)(kJmol-1)=-527.8+0.200T(K),ΔfG0(USn2)(kJmol-1)=-174.9+0.073T(K),ΔfG0(USn)(kJmol-1)=-176.9+0.064T(K) The Gibbs energy of formation for U3Sn7, USn2 and USn have been obtained for the first time.

► Gibbs energies of formation of the intermetallic compounds, USn3, U3Sn7, USn2 and USn were determined by using high temperature molten salt galvanic cell electromotive force method. ► The Gibbs energies of formation of USn3, U3Sn7, USn2 and USn with respect to α-U and liquid Sn, in the temperature range 682–905 K were determined to be −172.8 + 0.061 T, −527.8 + 0.200 T, −174.9 + 0.073 T and −176.9 + 0.064 T kJ mol−1, respectively. ► Gibbs energy formation of the U3Sn7, USn2 and USn are being reported for the first time.