Superparamagnetic Magnetite Nanotubes Synthesized by Template-Assisted Sol–Gel Autocombustion

Magnetite nanotubes with an average diameter of about 140 nm were synthesized by an AAO templateassisted sol–gel autocombustion method. The entire synthetic process is convenient, low-cost and nontoxic. The crystalline structure of the magnetite nanotubes was investigated by X-ray diffraction. From the diffraction pattern, we conclude that pure phase magnetite nanotubes were obtained. Tubular morphologies of the products were observed by transmission electron microscope. The as-prepared magnetite nanotubes have a high aspect ratios. The magnetic properties of the nanotubes were measured by a Physical Property Measurement System. The magnetic measurements indicate that the nanotubes have superparamagnetic characteristic at room temperature, and have ferromagnetic characteristic with a coercivity of about 518 Oe at 5 K. The blocking temperature T _B of the nanotubes are measured to be 95 K. The as-prepared magnetite nanotubes may find potential applications in bio-medicine.