Analysis of the oxygen potential of Th1−yUyO2+x

Oxygen potentials of UO 2 -ThO 2 solid solutions (Th 1-y U y O 2+x ) were retrieved from the literature and analyzed. For each datapoint the oxygen pressure p O2 , the nonstoichiometry x, the temperature T and the uranium concentration y was specified. The data were analyzed using the valency control model and the thermochemical model of Lindemer and Besmann for UO 2+x which was extended for the analysis of the Th 1-y U y O 2+x data. The solid solution is regarded as an ideal ternary solution of UO 2 , ThO 2 and a hypothetical compound U a O b . The thermodynamic properties of this compound U a O b were determined in two oxygen pressure ranges of the database. In this thermochemical approach ThO 2 is treated as an inert solvent that does not participate in any of the chemical equilibria describing the oxygen potential.