Preparation of Fe-Doped TiO_2 Nanotube Arrays and Their Room-Temperature Ferromagnetic Properties

摘要

Fe-doped titania nanotube arrays (NTs) were fabricated by electrochemical anodization on a Ti foil using Fe(NO_3)_3·2H_2O as iron source. Their morphology, structure and optical properties were investigated by field emission scanning electron microscopy, X-ray diffraction, UV-visible absorption spectroscopy and photoluminescence spectroscopy. The UV-visible reflection spectrum of the Fedoped TiO_2 NTs showed a red shift in wavelength of absorption and greater reflectivity compared with the undoped sample due to the Fe ion incorportion in TiO_2 lattices. The photoluminescence spectrum of the Fe-doped TiO_2 NTs shows two strong new peaks centered at 388 nm and 694 nm, besides the UV emission peak owing to the electronic transition mediated by the defect levels such as oxygen vacancies in the band gap. The magnetic property of the Fe-doped TiO_2 NTs exhibits a room temperature ferromagnetic characteristic with a saturation magnetization (M_s) of 0.146 × 10~(-2) emu/cm~3 and a coercive field of 60 Oe. And the cause of the magnetic properties has been discussed in detail.