Studies on the kinetics of oxidation of urania–thoria solid solutions in air

The oxidation behaviour of (UyTh1ˇy)O2 powders (ya 0:15; 0:30; 0:72 and 0:77) was studied by means of thermogravimetry. The oxidation was carried out under both isothermal and non-isothermal conditions. The limits of oxygen solubility in terms of O/M ratios of (UyTh1ˇy)O2 solid solutions, derived from the thermogravimetric data, were 2.08, 2.15, 2.35 and 2.36 for ya 0:15; 0:30; 0:72 and 0:77, respectively. A single-step oxidation was observed for (UyTh1ˇy)O2 solid solutions with ya 0:15‐0:77. The activation energy for the oxidation of (UyTh1ˇy)O2 powders with ya 0:15 and 0.30 (the final product is single-phase), was found to be (48.5 a 2.5) kJ mol ˇ1 . The activation energy for the oxidation of (UyTh1ˇy)O2 powders with ya 0:72 and 0.77 (the final product is a bi-phasic mixture) was found to be