Oxygen potential measurement of U 0.85 Am 0.15 O 2 at 1473, 1573, and 1673 K

Oxygen potential data of U 0.85 Am 0.15 O 2_ x were measured at 1473, 1573, and 1673 K by thermogravimetry. In U 1_ y An y O 2_ x , where An stands for Pu or Am, and for a given value of " y " and Oxygen/Metal ratio, the oxygen potential of U 1_ y Am y O 2_ x is higher than that of U 1_ y Pu y O 2_ x . The valence of cations in the hypostoichiometric region is similar to that of Nd-doped UO 2 . At the stoichiometric composition, it is estimated to be Am 3 + , U 4 + , and U 5 + (for charge compensation of Am 3 + ) in the stoichiometric composition. The experimental data were analyzed using a defect chemistry model, and a relationship connecting the oxygen-to-metal ratio, the temperature, and the equilibrium oxygen partial pressure was proposed.