Microemulsion-based synthesis of porous Co-Ni ferrite nanorods and their magnetic properties

Porous Co-Ni ferrite nanorods with a diameter of around 30-200 nm and a length of several micrometers were synthesized by a microemulsion-based method in combination with calcination at different temperatures. The morphologies and structures of the Co-Ni ferrite nanorods and their precursors of Co/Ni/Fe composite oxalate nanorods were characterized using a transmission electron microscopy, field emission scanning electron microscopy and X-ray diffractometer. Magnetization measurement was carried out using a vibrating sample magnetometer at room temperature. It showed that the saturation magnetization of Co_0.5Ni_0.5Fe₂O₄ nanorods obtained at 1000 °C could reach to 51.114 emu/g. The influence of calcination temperatures and compositions of the ferrites on their magnetic properties were also discussed. Therefore, Co-Ni ferrite nanorods could be easily prepared using this method and might be applied as catalysts, magnetic materials and microwave absorbers.