Mechanism of catalyst diffusion on magnesium oxide nanowire growth

In nanowire growth using vapor-liquid-solid (VLS) mechanism, controlling catalyst diffusion has been a key issue since VLS growth is essentially no longer feasible in the absence of catalyst on the tip. Here the authors demonstrate the controllability of catalyst diffusion on MgO nanowire growth by ambient pressure and discuss the underlying physical mechanism. Drastic enhancement of oxide nanowire growth was found when increasing the ambient pressure under oxygen atmosphere, and surprisingly even under argon atmosphere. This indicates that the ambient pressure rather than the amount of ambient oxygen dominates the oxide nanowire growth via suppressing the catalyst diffusion.