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This study explores the effect of heat treatment and helium (He) bubbles on the structure of SiC and the migration behaviour of silver (Ag) in SiC. Ag ions were implanted into polycrystalline SiC samples (Ag-SiC) at 350 °C and co-implanted with He ions at 350 °C (Ag + He-SiC). The samples were then annealed sequentially from 1000 °C to 1200 °C in steps of 100 °C for 5 hours. The implanted and subsequently annealed samples were characterized using Raman spectroscopy, transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS), and atomic force microscopy (AFM). Annealing the Ag-SiC samples at 1200 °C resulted in in some recovery of the SiC crystal structure and the formation of Ag precipitates along the damaged layer. These precipitates formed due to the segregation of silver, which migrated toward the bulk where radiation damage was less severe, with some silver being lost from the surface. In the case of the Ag + He-SiC sample, annealing at 1200 °C led to the formation of large cavities along the projected range, with bubbles forming at the amorphous-crystalline (a-c) interface. These bubbles appeared as surface blisters, and their exfoliation created holes, resulting in cavities in the highly defective region underneath the surface. The larger cavities caused He out-diffusion, leading to increased loss of He. The cavities also trapped Ag precipitates, resulting in Ag retention within the SiC. Additionally, the formation of bubbles at the a-c interface facilitated the migration of Ag toward the bulk at 1200 °C. These results provide valuable insights into the mechanisms of Ag migration in SiC, which are important for enhancing the safety of nuclear fuels.
