The Korean Journal of Ceramics

The Korean Ceramic Society (한국세라믹학회)
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Nonstoichimetry (x) of Nuclear Materials UO2+x and $(Ce_yU_{1-y})O_{2+x}$ at High Temperatures as a Function of Oxygen Activity$(a_o_2)$

  • Kang, Sun-Ho (School of Materials Science and Engineering, Seoul National University) ;
  • Yoo, Han-Ill (School of Materials Science and Engineering, Seoul National University) ;
  • Kim, Han-Soo (Korea Atomic Energy Research Institute) ;
  • Lee, Young-Woo (Korea Atomic Energy Research Institute)
  • Published : 1998.06.01
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Abstract

The oxygen nonstoichiometry (x) of UO$_{2+x}$ and $(Ce_yU_{1-y})O_{2+x}$ (y=0.05, 0.25) has been measured as a function of oxygen activity (a02) at 100$0^{\circ}C$ by a solid state coulometri titration technique. The results for UO$_{2+x}$ are in a good agreement with literature data and the ao2-dependence of the nonstoichimetry has been well explained with (2:2:2) cluster model. The equilibrium oxygen activity of $(Ce_yU_{1-y})O_{2+x}$ increases with Ce-content (y) for given nonstoichiometry (x), which is ascribed to the fact that Ce is present as Ce$^{3+}\; and\; Ce^{4+}$, and, therefore, the addition of Ce reduces the oxidation capacity of UO$_{2+x}$. From the oxygen activity dependence of x in $(Ce_yU_{1-y})O_{2+x}$ the defect structure of $(Ce_yU_{1-y})O_{2+x}$ is discussed.

Keywords

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