Atomic simulation of ion-solid interaction in ceramics

Understanding dynamic processes during ion irradiation, as well as irradiation-induced microstructural changes, requires fundamental knowledge on defect properties, defect generation in atomic collision processes, multiple ion-solid interactions and defect migration. The multiple scale simulation methods are presented in this paper, and in particular, an application on SiC is discussed in detail. Density functional theory (DFT) has been employed to determine defect energetics and the most favorable interstitial configurations in SiC. Based on DFT calculations, a new empirical potential has been developed in order to carry out large-scale simulations of microstructural evolution. Multimillion atom systems (up to 6 million) have been used to study defect production, defect clustering, multiple ion-solid interactions and structural evolution in SiC. The defect-stimulated growth and coalescence of clusters represents an important mechanism for irradiation-induced crystalline-to-amorphous transformation. The relative disordering and swelling behavior, as well as high-resolution transmission electron microscopy image simulations, based on molecular dynamics results, provide atomic-level interpretations of experimentally observed features in SiC