Influence of high pressure on the threshold displacement energies in silicon carbide : A Car-Parrinello molecular dynamics approach

The threshold displacement energies in silicon carbide under different pressures are determined with ab initio molecular dynamics. The results show that the threshold displacement energies change anisotropically in different crystallographic directions when high pressure is applied. However, the weighted average values for both the C and Si sublattice, which determine the defect production in a material under irradiation, are found to increase significantly with increasing external pressures. Besides, we have observed some new defect structures under high pressures which are not observed at ambient conditions. Our results show that irradiation under high pressures could decrease the production rate of point defects in SiC, thus greatly enhancing its resistivity against radiation damage. The combination of irradiation and high pressure technique hence provides a pathway to obtain new structure materials.