Atomistic simulations of a helium bubble in silicon carbide

Large scale molecular dynamics calculations have been carried out to investigate the properties of nanometric helium bubbles in silicon carbide as a function of helium density and temperature. A dedicated interatomic potential has been developed to describe the interactions between helium and SiC atoms. The simulations revealed that the helium density cannot exceed a certain threshold value, which depends on temperature, because of the plastic deformation of the SiC matrix. Both local amorphization at low temperatures, and nucleation and propagation of dislocations at high temperatures, have been identified as activated plasticity mechanisms. This work also predicts that very high pressure, up to 60 GPa could be reached in helium bubbles in silicon carbide.