Aligned Fe-doped carbon nanotubes (CNTs) have been synthesized via pyrolyzing the ferrocene in 1050 degrees C. The Fedoped CNTs had diameters of 40-80 nm and length up to similar to 7 mu m. Fe particles not only occurred at the tip of the CNTs, acting as the nuclei for CNTs growth, but also were doped on the surface of the CNTs or discontinuously encapsulated in the CNTs. Magnetic measurements showed that Fe-doped CNTs had ferromagnetically ordering temperature above room temperature and coercivities of 940 Oe at 5 K and 348 Oe at room temperature, respectively, which suggested that the aligned Fe-filled CNTs may have potential applications in data storage. Finally, a vapor-liquid-solid (V-L-S) mechanism was proposed for the aligned CNTs growth. (c) 2005 Elsevier B.V. All rights reserved.