Analysis of grain boundary sinks and interstitial diffusion in neutron-irradiated SiC

The widths of the interstitial loop denuded zone (DZ) along grain boundaries were examined for 3C-SiC irradiated at 1010-1380 C by transmission electron microscopy (TEM) in an effort to obtain the activation energy of interstitial migration. Denuded-zone widths as small as 17 nm were observed below 1130 C, indicating that a substantial population of 'TEM invisible' voids of diameter <0.7 significantly contribute to interstitial annihilation. By using the obtained loop DZ width and the matrix sink strength (including the invisible voids), the activation energy of interstitial diffusion was determined to be 1.5 eV for the slower moving Si interstitial of SiC by application of simple reaction-diffusion equations.