Abstract
A thermochemical representation of the fluorite structure AmO2-x phase was developed using the compound energy formalism approach assuming constituents of (Am4+)1(O2-)2, (Am4+)1(Va)2, (Am3+)1(O2-)2, and (Am3+)1(Va)2. The Gibbs free energies for the constituents and a set of interaction parameters were determined using reported oxygen potential-temperature-composition data. A good fit to the experimental information was obtained which well-reproduces the behavior. The representation is also in a format that will allow incorporation of other dissolved metals and thus will be useful in generating multi-component compound energy formalism representations for complex oxide nuclear and waste systems. A full assessment relating the fluorite structure phase to the phase equilibria for Am-O, however, must await adequate data for the remainder of the system.
