Nanotube arrays of Zn/Co/Fe composite oxides assembled in porous anodic alumina and their magnetic properties

Zn/Co/Fe composite oxide nanotubes were successfully synthesized using a 1:2:1 molar precursor solution of Zn(NO₃)₂, Co(NO₃)₂ and Fe(NO₃)₃ and anodic aluminum oxide as the substrate. To obtain the arrays of Zn/Co/Fe oxide nanotubes inside the anodic aluminum oxide templates, the precursor with template was treated in a muffle at 500 °C for 1 h. Characterization of the nanotubes using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) indicated that they are about 10 μm in length, with an outer diameter of about 200 nm and a wall thickness of about 30 nm. The grains that formed the nanotubes were about 10-20 nm in diameter. The products were also characterised by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Magnetization measurement was carried out using a vibrating sample magnetometer (VSM) at room temperature and showed that the coercivity of Zn/Co/Fe oxide nanotubes was small, ∼30 Oe. Therefore, Zn/Co/Fe oxide nanotubes could be easily prepared using this method and might be applied as catalysts, magnetic materials and microwave absorbers.