Control of magnesium oxide nanowire morphologies by ambient temperature

Although controlling morphologies of oxide nanowires formed using vapor-liquid-solid (VLS) mechanism is desired in developing functional oxide-nanowire applications, a comprehensive understanding of the key factors affecting oxide-nanowire VLS growth is still lacking. Here, the authors demonstrate the controllability of magnesium oxide nanowire morphologies by varying the ambient temperature and discuss the underlying mechanism. Decreasing the ambient temperature resulted in shorter, tapered, and square-rod shaped nanowires, whereas increasing the ambient temperature allowed fabricating longer and untapered nanowires. The variation of oxide-nanowire morphologies is interpreted in terms of the competition between the VLS growth and the sidewall growth due to the variation of adatom transport. (c) 2007 American Institute of Physics.