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 90degreesC with the reaction time of 6 h. The particle size ranges from 2 to 60 run 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 degreesC. The ferrite powders were compressed and sintered at various temperatures between 800 and 1000degreesC for 2 h. According to experimental results, the NiCuZn ferrite powders with high Cu content could be sintered at about 800degreesC. The density of the sintered Ni0.18CU0.31Zn0.51Fe2O4 ferrite was 5.01 g/cm(3) after sintering at 900degreesC. The initial permeability mu of this sintered sample is about 390 at frequency of 1 MHz. Its H-c value is about 0.7 Oe and B-s congruent to 3100G. We found that Cu substitution for Ni in NiZn ferrite would enhance the densification of the ferrite and subsequently increases the mu value as well as B-s value, and decreases the H-c value of the sintered ferrite. (C) 2004 Elsevier B.V. All rights reserved.