Synthesis of metallic glass nanoparticles by inert gas condensation

Abstract

Inert gas condensation (IGC) is a versatile method for the synthesis of ultrafine nanoparticles. While it has been mostly used in the synthesis of nanocrystalline particles, it has also been employed in the synthesis of metallic glass nanoparticles, which can be further used in the generation of nanostructured metallic glasses, known as nanoglasses. In this work, we use molecular dynamics simulations to investigate the IGC processes leading to the synthesis of $\mathrm{C}{\mathrm{u}}_{64}\mathrm{Z}{\mathrm{r}}_{36}$ amorphous nanoparticles. We investigate the growth of nanoparticles up to 7.3 nm diameter using long simulations of up to 130 ns, under relatively low pressures in the range of 4--10 bars. Results indicate a significant effect of pressure on the final structure of the amorphous nanoparticles, yet no clear influence on the segregation of Cu atoms to its surface. Cu segregation occurring at all pressures results in a thin Cu-rich layer, about 2.5 \AA{} thick, that coats all nanoparticles. Statistics of atomic Voronoi polyhedra shows that the fraction of full icosahedra in the nanoparticles produced at 4 bars is equivalent to that of bulk metallic glasses produced by melt and quench at ${10}^{9}\phantom{\rule{0.16em}{0ex}}\mathrm{K}/\mathrm{s}$. Higher pressures result in a lower fraction of full icosahedra.