Oxygen potential of hypo-stoichiometric Lu-doped UO2

Oxygen potentials of hypo-stoichiometric Lu-doped UO ₂, (U _0.80Lu _0.20)O _{2− x} , were experimentally investigated by thermogravimetric analysis using H ₂O/H ₂ gas equilibria at 1173, 1273 and 1473 K. The oxygen potentials of (U,Lu)O _{2− x} were higher than those of other forms of rare earth-doped UO ₂, specifically (U,Nd)O _{2 −x}, (U,Gd)O _{2− x}, and (U,Er)O _{2− x} . Slope analyses for plots of oxygen potential versus deviation from stoichiometry indicated that (U _0.80Lu _0.20)O _{2− x} had a similar defect structure to that of the other forms of rare earth-doped UO ₂. A relationship between the effective ionic radii and oxygen potentials was found for the hypo-stoichiometric rare earth-doped UO ₂.