Oxygen potential and defect equilibria in UO

UOの酸素ポテンシャルと欠陥平衡

加藤 正人   ; 渡部 雅  

Kato, Masato; Watanabe, Masashi

UOの酸素ポテンシャルは、化学的な相安定性や基礎特性を知るために重要な熱力学データである。これまで多くの研究が行われてきたが、大きなバラツキがあり精度の高い評価ができていない。本研究では、定比組成近傍の酸素ポテンシャルの測定を行い、文献値と合わせて欠陥平衡を評価し、酸素ポテンシャルの関係式を導出した。

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.