Fabrication and properties of Mn0.5Zn0.5Fe2O4 nanofibers

Zn-doped α-FeOOH nanofiber was synthesized by coprecipitation method. Then the α-FeOOH was enwraped by the complex of the Mn²⁺ and citric acid. The morphology of α-FeOOH did not transform after the calcination process and Mn_0.5Zn_0.5Fe₂O₄ nanofiber was successfully prepared. The phase, morphology, particle diameter and the magnetic properties of samples were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The results indicated that Mn_0.5Zn_0.5Fe₂O₄ nanofibers with an aspect ratio over 40 and a diameter of 20 nm were prepared. Compared with the amorphous Mn_0.5Zn_0.5Fe₂O₄, the anisotropy of the Mn_0.5Zn_0.5Fe₂O₄ nanofiber increased, resulting in the higher coercivity and magnetization of the obtained sample. With an increase in the calcination temperature, the diameter and the saturation magnetization of the sample increased, while the aspect ratio and coercivity decreased. The coercivity of the sample obtained at 700 °C was maximal (up to 185.4 Oe). The saturation magnetization of the sample obtained at 900 °C was maximal (up to 65.3 emu/g). The use of citric acid method prevented the presence of Mn(OH)₂, resulting in the decrease of the calcination temperature.