Study of Cu, Co, Mn and La doped NiZn ferrite nanorods synthesized by the coprecipitation method

The Zn- and Ni-doped spicular alpha-FeOOH precursor sample was obtained by coprecipitation-air oxidation method. The Ni0.5Zn5.5Fe2O4 nanorods with an average diameter of 40 nm and an aspect ratio of 20 were prepared after the calcination process for maintaining the morphology of alpha-FeOOH precursor. Cu, Co, Mn and La were doped into Ni0.5Zn0.5Fe2O4 to prepare Ni0.4M0.1Zn0.5Fe2O4(M represents Cu, Co, Mn, La) nanorods. The phase, morphology and particle diameter of the samples were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the aspect ratio of the Ni0.4M0.1Zn0.5Fe2O4 decreased with an increase in the absolute difference of the radius of the dopant ion and Fe2+. Therefore, the aspect ratio of the Ni0.4Cu0.1Zn0.5Fe2O4 nanorods obtained by doping Cu was maximal and the value was higher than 25. The magnetic properties were measured using a vibrating sample magnetometer (VSM), which indicated that the coercivity of the Ni0.4M0.1Zn0.5Fe2O4 sample decreased and the magnetization increased with an increase in the calcination temperature. The higher anisotropy due to the rod-like structure of the ferrites is responsible for the superior magnetic properties obtained in the present work compared to those reported for ferrites with irregular grain shapes. (C) 2010 Elsevier B.V. All rights reserved.