Statistico-Thermodynamical Studies of the Oxidation Equilibria of Uranium Dioxides
Journal Article
·
· Trans. Japan Inst. Metals (Sendai)
The process of oxidation and the oxidation equilibria were investigated on a homegeneous phase of a uranium oxide containing oxygen in stoichiometric excess. The rate of oxidation of UO/sub 2/ was measured in the range from 175 to 360 deg C by means of a spring thermobalance, and it was found that the oxidation in the concentration range of UO/sub 2/ to U/sub 3/O/sub 7/ occurred in a dlfferent process from that in the range of U/sub 3/O/sub 7/ to U/sub 3/O/sub 8/. From the results of measurements of the activation energy for oxidation, the dependence of the lattice constant on oxygen concentration in the range from UO/ sub 2/ to U/sub 3/O/sub 7/, and the observation on the change in density, it was deduced that the oxidation proceeds through the diffusion of oxygen ions which are produced from atmospheric oxygen by the reaction on the surface of the UO/sub 2/ crystal accompanied with the formation of electron deficits among uranium ions in the crystal. On the assumptions that these oxygen ions in stoichiometric excess occupy the interlattice points in the UO/sub 2/ crystal of the fluorite lattice type and the election deficits are randomly distributed among uranium ions in the form of U/sup 6+/ ions, the correlation between the equilibrium oxygen pressure and the oxygen concentration of the UO/sub 2/ crystal containing oxygen in stoichiometric excess was theoretically calculated. (auth)
- Research Organization:
- Tohoku Univ., Sendai
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-15-030684
- OSTI ID:
- 4840501
- Journal Information:
- Trans. Japan Inst. Metals (Sendai), Journal Name: Trans. Japan Inst. Metals (Sendai) Vol. Vol: 1: No. 1
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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