Metal and alloy nanowires: Iron and invar inside carbon nanotubes

Pyrolysis of hydrocarbons over metal catalysts has proved to be a very efficient and versatile technique for generating metal-filled carbon nanotubes. At reduced pressures Fe-filled nanotubes are formed efficiently from ferrocene and C-60. Recently, alloys such as invar (Fe65Ni35) were successfully introduced in carbon nanotubes by pyrolysing aerosols of nickelocene/ferrocene (CP2Ni/CP2Fe) mixtures dissolved in benzene. With the introduction of Invar in carbon nanotubes it is now possible to study the physico chemical properties of these wires. Furthemore, the alloy formation notably reduces the formation of unwanted by-products such as amorphous carbon, or metal encapsulated particles. The results also confirm that the use of C-60 or Ni/Fe also enhances the growth and crystallinty of the products. The products have been characterised by SEM, HRTEM, EELS, XRD and SQUID. The magnetic properties of metal- and alloy-filled nanotubes may be applied to the fabrication of high density magnetic storage devices, magnetic inks, etc.