Simulation of defect formation, amorphization and cluster formation processes in nc-TiN/a-Si3N4 nanocomposite under Xe irradiation

摘要

The research of defect formation and clusterization processes by means of a molecular dynamics method both in nc-TiN nanocrystals and amorphous a-Si3N4 matrix, as the constituents of nc-TiN/a-Si3N4 nanocomposite, under exposure to Xe implantation was the aim of the present study. Dependences of the clustered Xe atoms fraction on their concentration and temperature of post-irradiation annealing were analyzed. At defect formation process in nc-TiN nanocrystals, there is a size effect consisting in intensification of the radiation point defects formation with the reduction of nc-TiN nanocrystals size and concurrent predominant formation of the dangling Si- and N-bonds in a-Si3N4 matrix. Accumulation of these defects at the irradiation leads to amorphization of nc-TiN nanocrystals with the size less than 8 nm and to formation of the nanopores in a-Si3N4 matrix. The important role of the radiation defects subsystem in transport processes of implanted Xe both in TiN close-packed lattice as well as in a-Si3N4 amorphous matrix is shown. There is a much higher extent of intensity of xenon atoms clusterization processes in the amorphous matrix. The results of the simulation are compared to existing experimental data. (C) 2017 Elsevier B.V. All rights reserved.