Tailoring the shape of vanadium nanoparticles produced by gas aggregation source

Abstract

In this study, we have analyzed experimentally different strategies for controlling the morphology of vanadium nanoparticles produced by means of a magnetron-based gas aggregation source. It is shown that while low magnetron currents and aggregation pressures lead to the formation of cubic vanadium nanoparticles, which is most likely connected with different kinetics growth modes on {100} and {110} surfaces of vanadium, higher magnetron currents and pressures result in the spherical-like but highly irregular morphology of produced NPs. Furthermore, it was found that the size of the nanoparticles may be adjusted by introducing He into the working gas mixture. An increase in the He partial pressure causes a substantial decrease in the size of nanoparticles but has no impact on their shape. This effect is predominately connected with the enhanced nucleation caused by He, which favours the production of a higher number of smaller nanoparticles. Finally, the vanadium nanoparticles, irrespective of their initial shape, may be transformed into fully spherical ones by introducing oxygen into the main deposition chamber, which is connected by their extensive heating during their in-flight oxidation.