Unraveling interaction mechanisms of Kr cavities with Ag in irradiated silicon carbide under high temperatures

Polycrystalline 3C-SiC was sequentially implanted with 3.0 MeV and 1.2 MeV Kr¹²⁺ ions, followed by annealing at 1500 °C to form a double-layer of nanosized Kr cavities. Subsequently, 2.6 MeV Ag¹⁹⁺ ions were implanted into both the Kr-implanted sample and a pristine 3C-SiC sample, followed by annealing at 1500 °C. Experimental results revealed the formation of a Kr-Ag-Kr sandwich structure in the Kr-implanted 3C-SiC after Ag¹⁹⁺ ion implantation. At 1500 °C, Ag atoms exhibited localized diffusion in 3C-SiC, forming nanoscale clusters. Compared to pristine 3C-SiC, the Kr-implanted 3C-SiC showed smaller Ag clusters with a higher distribution density. The independent existence of Kr cavities and Ag clusters was observed, with Ag atoms preferentially diffusing into regions of higher damage. Enhanced diffusivity of Ag atoms was noted in samples containing Kr cavities. This study provides valuable insights into the diffusion behavior of fission product Ag in the SiC layer of TRISO fuel particles.