Fe-Co and Fe-Ni Nanocluster Wires by Hydrogen Reduction in Nanoporous Alumina Templates

This paper reports the fabrication, formation mechanism, nanostructure and magnetic properties of Fe₅₀Co₅₀, Fe₆₅Co₃₅ and Fe₅₀Ni₅₀ (at.%) nanocluster wires (NCWs) with different aspect ratios fabricated by thermal decomposition of metal nitrates and subsequent hydrogen reduction in nanoporous anodized aluminum oxide (AAO) templates. The as-synthesized NCWs have diameters in the range of 80-360 nm, and lengths in the range of 0.5-10 μm. The NCWs are composed of roughly round-shaped nanoclusters in the range of about 5-50 nm in size and a weighted average size of 14 nm with a mixture of single-crystal and poly-crystalline structures. The Fe-Co NCWs have a bcc structure while the Fe₅₀Ni₅₀ NCWs have an fcc structure. An intrinsic coercivity at room temperature _iH_c of 1.15 kOe was obtained for the Fe₆₅Co₃₅ NCWs. The NCWs exhibit the easy magnetization direction along the length of the nanowires as a result of the shape anisotropy.