Knudsen effusion mass spectrometric studies over (USn3+U3Sn7) two-phase region of U-Sn system

Vaporisation studies over (USn3+U3Sn7) "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 (USn3+U3Sn7) "twophase" field and the p-T relation was derived as log (psn/Pa) = ((-14580 +/- 91)/(T/K)) + (8.82 +/- 0.08) (1050-1226 K). The vaporisation reaction 3USn(3)(s) = U3Sn7(s) + 2Sn(g) was evaluated by second law method. The Gibbs energy of formation of USn3(s) was derived as Delta(f)G degrees(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. (C) 2017 Elsevier B.V. All rights reserved.