Effect of low-dose BaO doping on structure and oxidation of UO2

The effects of different doping amounts of BaO on the structure and oxidation behavior of UO 2 were investigated by a series of methods. The results indicated that the solid solutions (U 1- y Ba y )O 2- y was formed after sintering. With the increase of y value, the lattice parameters of (U 1- y Ba y )O 2- y and oxygen vacancies increased, OOT and MRT gradually rose and O/(U + M) final decreased. The oxidation products were characterized by XRD, SEM and XPS. As y value increased, the average valence state of uranium decreased, the oxidation became incomplete and the average activation energy of (U 1- y Ba y )O 2- y increased from 89.50 to 125.15 kJ/mol. Graphical BaO is dispersed in UO 2 matrix and formed oxygen vacancies. The delayed UO 2 oxidation is more obvious with more BaO doping. And the difference of U valence state is found from the oxidation products at 550 ℃.