Oxygen non-stoichiometries in (Th0.7Ce0.3)O2−x

Oxygen non-stoichiometry in (Th0.7Ce0.3)O2−x oxide solid solutions was investigated from the viewpoint of Ce reduction. The oxygen non-stoichiometry was experimentally determined by means of thermogravimetric analysis as a function of oxygen potential at 1173, 1273 and 1373 K. Features of the isotherms of oxygen non-stoichiometry in (Th0.7Ce0.3)O2−x similar to those in oxygen non-stoichiometric actinide and lanthanide dioxides were observed. The oxygen non-stoichiometry in (Th0.7Ce0.3)O2−x was compared with those of CeO2−x and (U0.7Ce0.3)O2−x. It was concluded that the Ce reduction has some relation to defect forms and their transformations in the solid solutions.