Characterization of Fe nanorods grown directly from submicron-sized iron grains by thermal evaporation

Abstract

Materials with size down to the nanometer scale exhibit melting points lower than that of their bulk form. This may lead to new catalyst-free approaches for fabricating metal/metal oxides nanostructures. In this Brief Report, we report the observation of Fe nanorods grown directly from submicron-sized Fe grains on Si substrates at $\ensuremath{\sim}650\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$, by thermal evaporation. The iron nanorods are single crystalline, several tens of nanometers in diameter, and several hundred nanometers long, and are coated with a thin (several nanometers thick), single-crystalline ${\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ layer. The growth of Fe nanorods by this approach is due to the partial melting and iron droplet formation on submicron-sized grains at temperatures much lower than its melting point. This study opens a new way to fabricate metal/metal oxides nanostructures without catalysts, at relatively low substrate temperatures.