MD and TEM evaluation of swift Xe ion induced latent tracks in Si3N4

Abstract

As known silicon nitride ceramics is considered as a candidate material for inert matrix fuel hosts used for transmutation of minor actinides. Unfortunately, by now very limited data is devoted to investigate of its stability under high energy heavy ion irradiation simulating fission fragment impact. Aim of our present study is a comparative analysis of parameters of latent tracks induced with swift Xe ion irradiation in polycrystalline Si₃N₄ using molecular dynamic (MD) simulation and high resolution transmission electron microscopy (TEM). Silicon nitride samples were irradiated with 220 MeV xenon ions at room temperature to fluence 5 × 10 11 cm^-2 that correspond to ion track non overlapping regime and allows to analyze single ion track regions. The calculated MD and experimental TEM values of track diameter for 220 MeV Xe irradiation are found to be in a good agreement and equal about 2 nm, whereas the threshold ionizing energy loss for track formation predicted by MD is lower than threshold value from TEM measurements (11.5 keV/nm vs 15 keV/nm). The averaging of all presented data gives the threshold energy loss level ∼ 13 ± 2 keV/nm