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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/spl deg/C, resulting in nanoparticles exhibiting normal ferrimagnetic behavior. The nanotructured Ni/sub 0.2/Zn/sub 0.8-x/Cu/sub x/Fe/sub 2/O/sub 4/ (x=0.2/spl sim/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/sub S/ of Ni/sub 0.2/Zn/sub 0.8-x/Cu/sub x/Fe/sub 2/O/sub 4/ in this work as measured was about 51 emu/g at 77 K …