Growth studies, TEM and XRD investigations of iron-filled carbon nanotubes

The formation mechanism of iron filled carbon nanotubes on oxidized silicon substrates precoated with thin metal layers (Fe, Co) has been studied. These filled structures were aligned perpendicular to the substrate surface. The nanotubes were produced by the thermal decomposition of ferrocene in an argon flow. We have studied the nanotube morphology and geometry (diameter, length) in detail. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and selected area electron diffraction (SAED) were used to analyze the iron nanorods inside the nanotubes. These investigations have revealed a majority fraction of α-Fe and small amounts of γ-Fe and Fe 3C. Moreover only single crystalline iron was found. In summary we conclude that iron filled carbon nanotubes with this CVD route are formed via an open-ended, base growth mechanism.