Preparation of NiCuZn ferrite nanoparticles from chemical co-precipitation method and the magnetic properties after sintering

NiCuZn ferrite nanoparticles with composition of NixCuyZn1−x−yFe2O4 (where x=0.15–0.5 and y=0–0.35) were prepared by the chemical co-precipitation method at various reaction temperatures with a final pH value of 12. From the analysis of X-ray diffraction patterns, the nanocrystalline NiCuZn ferrite particles could be obtained at pH=12 and reaction temperature between 30 and 90 °C with the reaction time of 6 h. The particle size ranges from 2 to 60 nm by observation of transmission electron microscopy. Uniform size of cubic crystalline particles with particle size of about 30 nm were obtained at reaction temperature of 70 °C. The ferrite powders were compressed and sintered at various temperatures between 800 and 1000 °C for 2 h. According to experimental results, the NiCuZn ferrite powders with high Cu content could be sintered at about 800 °C. The density of the sintered Ni0.18Cu0.31Zn0.51Fe2O4 ferrite was 5.01 g/cm3 after sintering at 900 °C. The initial permeability μ of this sintered sample is about 390 at frequency of 1 MHz. Its Hc value is about 0.7 Oe and Bs≅3100 G. We found that Cu substitution for Ni in NiZn ferrite would enhance the densification of the ferrite and subsequently increases the μ value as well as Bs value, and decreases the Hc value of the sintered ferrite.