Molecular dynamics simulation of displacement cascades in cubic silicon carbide

Abstract

We use molecular dynamics (MD) methods to study collision cascades in cubic silicon carbide (3C-SiC), which is a candidate for various applications in nuclear industries. One Tersoff potential, which can reproduce the thermal and elastic properties of 3C-SiC, was firstly connected with ZBL potential. Collison cascades were generated by primary knock-on atoms (PKAs) with damage energies ranging between 1 keV and 10 keV at 300–1800 K. It was found that the temperature weakly influences the production of defects in the temperature range (300–1800 K). However, the number of point defects increases significantly as the PKA-energy increases. Carbon defects dominate most of the defects formed in collision cascades, and the dominance becomes less significant with the increase of temperature. Some high-density interstitial point defects were observed in the evolution of the collision cascade. As the PKA-energy increases, more and more defect clusters with larger sizes can be observed. For the current PKA energy range (≤10 keV), clusters with 1–5 vacancies and with 1–4 interstitials can be found, and clusters with a larger size are rare at the end of the quenching stage. The number of these defect clusters with various sizes is temperature independent. In these defect clusters, the carbon content exceeds 50% in most conditions. In addition, the carbon ratio in interstitial clusters is usually higher than the carbon site ratio in vacancy clusters. This work not only enriches the knowledge of the the number, size distribution and compositions of point defects and their clusters induced by neutron irradiation, but also can be input for the long-term simulation methods to understand the evolution of irradiated defects in 3C-SiC. Furthermore, the defect information can be used to study the thermal and elastic properties of 3C-SiC in future work.