Knudsen effusion mass spectrometric studies over (USn 3 +U 3 Sn 7 ) two-phase region of U-Sn system

Abstract Vaporisation studies over (USn 3 +U 3 Sn 7 ) “two-phase” field have been carried out by employing Knudsen effusion mass spectrometry (KEMS) in the temperature range of 1050–1226 K. Sn(g) was the species observed in the mass spectrum of the equilibrium vapour phase over the samples (71.5 at% Sn and 73.0 at% Sn). The partial pressure of Sn(g) was measured as a function of temperature over (USn 3 +U 3 Sn 7 ) “two-phase” field and the p-T relation was derived as log (p Sn /Pa) = ((−14580 ± 91)/(T/K)) + (8.82 ± 0.08) (1050–1226 K). The vaporisation reaction 3USn 3 (s) = U 3 Sn 7 (s) + 2Sn(g) was evaluated by second law method. The Gibbs energy of formation of USn 3 (s) was derived as Δ f G m ° ( U S n 3 , s , T ) (±1.8) = −173.4 + 0.055 T (K) (kJ mol −1 ) (1050–1226 K). The mass spectrometric studies on this system have been carried out for the first time.