요 약 우라늄 및 희토류(RE : rare-earth) 산화물의 황화반응에 대한 M-O 2 -S 2 상태도 및 Gibbs 자유에너지 변화(∆G o )와 같은 열역학적 Abstract In order to evaluate the feasibility of selective sulfidization of uranium and rare-earth(RE) oxides, an analysis on thermodynamic data, such as M-O 2 -S 2 phase stability diagram and changes of Gibbs free energy for sulfidization of uranium and rare-earth oxides were carried out. Comparing RE-O 2 -S 2 with U-O 2 -S 2 phase stability diagram at wide range of sulfur potential, UO 2 remains

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... ted, while RE oxides are sulfidized. The Gibbs free energy change(∆G o ) of sulfidization of RE oxides is lower than that of uranium oxides. Thus, the selective formation of RE sulfides is possible during sulfidization of RE and uranium oxides at lower temperature. CS 2 was selected as a sulfidizing agent, because it is a stronger sulfidizing agent than other agents and reacts at lower temperature.