Determination of oxygen in ternary uranium oxides by a gravimetric alkaline earth addition method

The applicability of a gravimetric method based on alkaline earth metal addition for the determination of oxygen in ternary uranium oxides of the type M—U—O (M=La, Ce and Th) is described. The oxide sample is mixed with MgO or Ba_2.8UO_5.8 and heated in air under suitable conditions. Because uranium is completely oxidized to the hexavalent state during the reaction, oxygen can be determined from the weight change. Oxygen in La_yU_1-y O_2+x is determined up to y = 0.8 with a standard deviation for x of ±0.006 with MgO. For Th_yU_1-y O_2+x, the value of x is determined with Ba_2.8UO_5.8 with a standard deviation of ±0.01 at y = 0.8. For Ce_yU_1-y O_2+x, the method can be applied only for low cerium concentrations where y = 0–0.2; the value for x with Ba_2.8UO_5.8 at y = 0.2 showed a standard deviation of ±0.002.