Self-radiation damage in 244Cm oxide and aluminate

Self‐radiation from α‐decay of 244 Cm causes lattice swelling, phase transformations, and loss of structure in several Cm compounds. In Cm oxides, the percentage swelling at saturation decreases with decreasing symmetry: Swelling in fluorite (fee) CmO 2 (∼0.3%) is approximately twice that in bee C ‐type Cm 2 O 3 ; monoclinic Cm 2 O 3 does not swell. CmO 2 swells with time according to Δa/α=3.0×10 −3 (1–e −1.7×104λt ), essentially the same relation as for PuO 2 and AmO 2 . The rate of structure loss of Cm oxides decreases with increasing temperature of prior heatings. In CmAlO 3 the metamict state is produced before swelling reaches saturation. Radiation‐induced transformation at room temperature produces metastable phases that normally exist at higher temperatures, e.g. bcc C ‐type Cm 2 O 3 transforms to hexagonal A‐type Cm 2 O 3 , and rhombohedral CmAlO 3 becomes cubic.