Structural and magnetic properties of nickel ferrite nanoparticles synthesized via a template-assisted sol–gel method

Spinel nickel ferrite (NiFe2O4) nanoparticles with high specific area and excellent magnetic properties were synthesized via a template-assisted sol–gel method. The effects of template type on the structural properties, magnetic properties, and heating rate are investigated. Results of XRD and TEM indicate that the NiFe2O4 particles synthesized using templates exhibit a typical single phase spinel structure in nano size. The sample using sponge or cotton as template presents the best saturation magnetization (66.6 emu/g) and the lowest coercivity (137.7 Oe), respectively, and their specific surface area is enhanced greatly from 20.1 m2/g to 55.7 m2/g. It is found that the calculated hysteresis loss agrees well with the measured radio frequency heating rate.