Atomistic simulations of resistance to amorphization by radiation damage

摘要

We use molecular-dynamics simulations to study processes related to resistance to amorphization by radiation damage. We simulate high-energy radiation events in SiO_2, GeO_2, TiO_2, Al_2O_3, and MgO, and find that simulation results match the experiments. We discuss the difference between the damage that the structures along this series can support. We find that for the same material, activation barriers for damage recovery can strongly depend on the degree of structural damage. We observe that the effect of resistance to amorphization is primarily governed by the relaxation processes at the time scales of several picoseconds. On this time scale, we observe two distinct relaxation processes, reversible elastic deformation around the radiation cascade and recovery of the in-cascade damage of high topological disorder. Finally, we discuss how resistance to amorphization is related to interatomic interactions and to the nature of the chemical bond.