Microstructure and magnetic properties of nanostructured NiZnCu ferrite powders synthesized by sol-gel process

Nanostructured spinel NiZnCu ferrites were prepared by the sol-gel method from metal nitrate raw materials. Analyses by X-ray diffraction and scanning electron microscopy showed the average particle size of NiZnCu ferrite was under 50 nm. The single phase of NiZnCu ferrites was obtained by firing at 250°C, resulting in nanoparticles exhibiting normal ferrimagnetic behavior. The nanotructured Ni_0.2Zn_0.8-xCu_xFe₂O₄ (x=0.2∼0.6) were found to have the cubic spinel structure. NiZn ferrite phase substituted by Cu was obtained before using the additive but hematite phase partially appeared at x=0.6. On the other hand, the hematite phase in this NiZnCu ferrite disappeared after using the additive of acetyl acetone small amount. The saturation magnetization M_S of Ni_0.2Zn_0.8-xCu_xFe₂O₄ in this work as measured was about 51 emu/g at 77 K and 19 emu/g at room temperature, respectively.