Chemical potential of oxygen in (U, Pu) mixed oxide with Pu/(U+Pu) = 0.46

Abstract Chemical potential of oxygen in (U,Pu) mixed oxide with Pu/(U + Pu) = 0.46 was measured for the first time using H 2 /H 2 O gas equilibration combined with solid electrolyte EMF technique at 1073, 1273 and 1473 K covering an oxygen potential range of −525 to −325 kJ mol −1 . The effect of oxygen potential on the oxygen to metal ratio was determined. Increase in oxygen potential increases the O/M. In this study the minimum O/M obtained was 1.985 below which reduction was not possible. Partial molar enthalpy Δ H ¯ O 2 and entropy Δ S ¯ O 2 of oxygen were calculated from the oxygen potential data. The values of −752.36 kJ mol −1 and 0.25 kJ mol −1 were obtained for Δ H ¯ O 2 and Δ S ¯ O 2 respectively.