Fe3O4 nanowire arrays synthesized in AAO templates

Fe₃O₄ nanowire arrays with an average diameter of about 120 nm and lengths up to 8 m were synthesized in anodic aluminum oxide templates through electrodepositing and heat treating a precursor -FeOOH. The nanowires have a polycrystalline spinel structure with a=8.31 Å and each nanowire is composed of fine particles. Influences of the sintering and the reducing temperatures on the products have been demonstrated by Mössbauer spectra and X-ray diffraction. It was found that high-coercivity nanowires can be obtained when the precursor was sintered at 500 °C in air and then reduced at 325 °C in H₂. Hysteresis loops measured at room temperature show a clear perpendicular magnetic anisotropy. PACS 75.75.+a; 81.07.-b