<報文>酸化ウランに関する基礎的研究(第2報) : UO_2,U_4O_9及びU_3O_8間の500-1,200℃に於ける平衡の測定

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Oxidation and reduction equilibria among UO_2,U_4O_9 and U_3O_8 were measured with a flow method up to 1,200℃. It was found from the present results that the knowledge about relation-ship among p_<O_2>, O/U ratio and temperature in the 1st report could be extended to higher temperatures, and a new phase diagram of UO_2-U_3O_8 system was proposed. In this temperature and composition range, there are three uranium oxides ; UO_2,U_4O_9 and U_3O_8. UO_2 increases its oxygen solubility with rising temperature above 580℃, and below this temperature, the solubility increases with lowering temperature. The oxygen rich side of this region is heterogeneous and expressed as UO_<2+x>+U_4O_9. Its upper limit was found to be 1,073℃. The temperature dependence of oxygen potential was given by the following equations : 2U_4O_9=8UO_2 (saturated with O)+O_2,log P_<O_2>=-53,158/T+17.059 logT-0.02713T+17.715. Above 800℃ it may be simplified as follows : logP_<O_2>=-21,884/T+11.265. In the composition range of U_4O_9-U_3O_8,it was found to be homogeneous solid solution up to 1,200℃.
東北大学の論文
1961-02-24