Oxygen potential measurements of Am 0.5Pu 0.5O 2−x by EMF method

Abstract

The dependence of the oxygen potentials on oxygen non-stoichiometry and temperature of Am 0.5Pu 0.5O 2− x has been obtained by the electromotive force (EMF) method with the cell: (Pt) air |Zr(Ca)O 2− x | Am 0.5Pu 0.5O 2− x (Pt). The x value of Am 0.5Pu 0.5O 2− x was changed at 1333 K over 0.02 < x ⩽ 0.25 by the coulomb titration method. The temperature dependence of the oxygen potential was also measured over the range of 1173–1333 K. It was found that the oxygen potential decreased from −80 to −360 kJ mol −1 with increasing x from 0.021 to 0.22 at 1333 K and that it remained almost constant at −360 kJmol −1 around x = 0.23. It was concluded that Am 0.5Pu 0.5O 2− x should be composed of the single fluorite-type phase over 0.02 < x ⩽ 0.22 and the mixed phases of fluorite-type and (Am, Pu) 9O 16 at around x = 0.23.