Shyrokorad D. Evolution of free metal clusters under low-energy argon clusters bombardment

The evolution of mono- and bimetallic metastable Janus-like clusters at 5, 100 and 500 ps time intervals after the impacts with Ar1, Ar2 and Ar13 particles with energies up to 1.4 keV is considered. Cu, Cu-Au, Ni-Al and Cu-Bi clusters which consisted of 26 to 390 atoms and had different mixing heat of their components were investigated. The bombardment was carried out with Ar1, Ar2 and Ar13 particles with energies from 1 to 1400 eV. The simulation was performed in the framework of classical molecular dynamics using the potentials of EAM and Akland to describe the interactions between metal atoms with MPI and OpenMP technologies implementation. A significant increase of the sputtering yields, with a change of the mainly sputtered component in some cases, and atoms’ displacement intensities with an increase in the size and energy of the bombarding particle along with strong growth of the potential energy and heating temperature of the clusters was shown. A gradual transition from the cascade-recoil to thermal mixing and sputtering mechanism in the process of the evolution of the bimetal cluster with increased temperature and intermixing of the components supported by the negative mixing heat was traced. Notable synergistic effect for clusters’ sputtering yields growth was found in the case of Ar2 and Ar13 bombardment compared to Ar bombardment. The formation of shell nanostructures with increased number of Cu atoms in the cores and Bi atoms in the closed shell or to a lesser extent increased number of Au atoms in the outer layer under the Ar13 particles bombardment of Cu-Bi and Cu-Au clusters correspondently was investigated. For the case of Ar1 at relatively low temperatures and insignificant sputtering, an incompleteness of the atomic shell in the Cu-Bi cluster and a significant heterogeneity of the components’ mixing in the Cu-Au cluster were observed.