Characterisation of uranium vacancies in hyper stoichiometric uranium dioxide

An experimental method, based on measurements of the expansion of a single crystal as a function of the p(O2) was used to determine the concentration of uranium vacancies in hyperstoichiometric uranium dioxide. The results are consistent with the concentration of electrical carriers measured in the same conditions, they are also in qualitative agreement with a theoretical modelling proposed in the literature. However, an improved interpretation would require to take into account the clusters of oxygen interstitials and vacancies.