Oxygen potential and defect equilibria in UO

Kato, Masato   ; Watanabe, Masashi  

Uranium di-oxide (UO) is nonstoichiometric compound, and the stoichiometry significantly affects thermal properties. Therefore, oxygen chemical potential is one of important thermodynamic data to evaluate phase stability and to know properties. Many researches have measured oxygen chemical potential as functions of temperature and oxygen-to-uranium (O/U). However, it is difficult to derive correlation equation to represent the oxygen potential because of large uncertainty in measurement data and complicated mechanism. In this report, the oxygen chemical potential was determined by gas equilibrium method, the defect equilibria was evaluated, and the correlation equation was derived.