Measurements of O/U ratio and oxygen potential for UO2+x (0.LEQ.x.LEQ.0.1).
- 1 January 1983
- journal article
- Published by Taylor & Francis in Journal of Nuclear Science and Technology
- Vol. 20 (3) , 228-236
- https://doi.org/10.3327/jnst.20.228
Abstract
The 0/U ratios of UO2+x (0≤x≲0.1) were determined at 1,000 and 1,200°C, using a thermobalance in atmospheres of controlled oxygen pressures set by CO/CO2 gases. The oxygen potentials corresponding to the x values were measured in situ with a solid electrolyte oxygen sensor. For x≳0.015 the present δG O 2 data agree well with the previously published data. In the range of 0≤x≲0.015, the increasing disagreement at smaller values of x was indicated; the present δG O 2 values are 2 to 15 kcal/mol more negative than the prior thermogravimetric data. The results also showed that a reverse in δG O 2 at 1,000 and 1,200°C occurs in the range of 2.003≤O/U≤2.015. The maximum in the plot of the partial molar entropy δS O 2 vs. O/U ratio has consequently been found near δS O 2=11 e.u. for O/U = 2.007. This δS O 2 value is considerably high in comparison with Markin & Bones' EMF data, suggesting a characteristic configuration of oxygen in the lattice near UO2.007.Keywords
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