Alpha‐Decay‐Induced Amorphization in Complex Silicate Structures

Alpha decay in Cm‐doped Ca 2 Nd 8 (SiO 4 ) 6 O 2 , Pu‐doped ZrSiO 4 , and natural ZrSiO 4 minerals results in the simultaneous accumulation of point defects and amorphous regions that both contribute to the macroscopic swelling. A composite model for the macroscopic swelling is used to determine the amorphous fraction as a function of cumulative alpha‐decay events. The dependence of the derived amorphous fraction in Ca 2 Nd 8 (SiO 4 ) 6 O 2 on cumulative alpha‐decay events is consistent with amorphization occurring directly within an individual displacement cascade. In ZrSiO 4 , on the other hand, the rate of amorphization is lower and the derived amorphous fraction as a function of cumulative alpha‐decay events is consistent with models for amorphization occurring as a result of the local accumulation of high‐defect concentrations from the multiple overlapping of displacement cascades.