Microscopic effects of self-radiation damage in 244Cm-doped LuPO4 crystals

Abstract

Microscopic effects of self-radiation damage in 244Cm-doped LuPO4 crystals were examined with transmission electron microscopy. These LuPO4 crystals had been doped with 1 wt% 244Cm and exposed to a radiation dose as high as 5 × 1016 α-decay events/mg over 18 years. The microscopic analysis revealed dense arrays of individual defect clusters and numerous bubbles. Whereas, the defect clusters may be interpreted as residuals of alpha-recoil tracks, the bubbles likely resulted from the α-particles generated during the decay events. The bubbles were found to coalesce under electron beam irradiation. Despite the high accumulated dose over the 18 years, the samples exhibited sharp diffraction patterns and periodic lattice spacings. This finding indicated that the samples remained largely crystalline and that the radiation-induced lattice damage was recovered at a rate comparable to that of damage production. This high recoverability is discussed with respect of various annealing processes that may have occurred in the samples.