Synthesis of Magnetite Nanorods from the Reduction of Iron Oxy-Hydroxide with Hydrazine

Nanowires and nanorods of magnetite (Fe3O4) are of interest due to their varied biological applications but most importantly for their use as magnetic resonance imaging contrast agents. One-dimensional (1D) structures of magnetite, however, are more challenging to synthesize because the surface energy favors the formation of isotropic structures. Synthetic protocols can be dichotomous, producing either the 1D structure or the magnetite phase but not both. Here, superparamagnetic Fe3O4 nanorods were prepared in solution by the reduction of iron oxy-hydroxide (beta-FeOOH) nanoneedles with hydrazine (N2H4). The amount of hydrazine and the reaction time affected the phase and morphology of the resulting iron oxide nanoparticles. One-dimensional nanostructures of Fe3O4 could be produced consistently from various aspect ratios of beta-FeOOH nanoneedles, although the length of the template was not retained. Fe3O4 nanorods were characterized by transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and SQUID magnetometry.