Oxygen potential measurements of Am0.5Pu0.5O2−x by EMF method

A thermodynamic study of the Pu–Am–O system

“…Two oxygen potential measurements are known for the ternary system: on sample with same 9% Am content by thermogravimetric analysis with H 2 O/H 2 gas equilibrium and dilute O 2 gas at 1123, 1273 and 1423 K by Osaka et al [2] and on sample with 50% Am by electromotive force method at 1333 K by Otobe et al [3] using the same experimental system as for the AmO 2Àx study [29]. It was concluded that the effect of Am addition to PuO 2Àx on the phase relation was to increase the miscibility gap temperature [1].…”

“…The aspects of the oxygen potential could be interpreted based on several interactions between Pu and Am and sequentially their valence state changes [2]. Am 0.5 Pu 0.5 O 2Àx should be composed of a single fluorite-type phase over 0.02 < x 6 0.22 and the mixed phases of fluorite type and (Am, Pu) 9 O 16 at x = 0.23 [3]. The discrepancies of this study with the other available data in the binary Am-O system make its reliability questionable.…”

“…The phase relations of PuO 2Àx containing 9% Am were studied by means of X-ray diffraction analysis, ceramography and differential thermal analysis, with different O/M (M = Pu + Am) ranging from 1.90 to 2.00 [1]. In addition, the oxygen potential measurements [2] on the same samples were performed using thermogravimetric analysis with H 2 O/H 2 gas equilibrium and dilute O 2 gas at 1123, 1273 and 1423 K. Recently, oxygen potential measurements were reported for Pu 0.5 Am 0.5 O 2Àx at T = 1333 K using the electromotive force method [3]. Data on the vapour pressure, another important fuel design property, of the mixed Pu/Am oxides are lacking.…”

Thermochemical and thermophysical properties of minor actinide compounds

“…The oxygen potentials of AmO 2Àx [41], (Np,Am)O 2Àx [42] and (Pu,Am)O 2Àx [43] were measured as a function of the oxygen nonstoichiometry x and temperature by the electromotive force method with a zirconia solid-electrolyte. For the measurements disks of the oxides with 3 mm in diameter and 1 mm in thickness were prepared.…”

Determination of Thermodynamic and Transport Properties of Non-Stoichiometric Oxides

“…The reference system is either a gas (pure oxygen, air) or a metal-metal oxide mixture (Fe-FeO, Cu-Cu 2 O, PdPdO, etc.). Examples of measurements on non-stoichiometric oxides are numerous [Mari et al, 1977;Nakamura & Fujino, 1987;Otobe et al, 2009;Porat & Riess, 1994].…”