Preparation and magnetic properties of Ni0.25Cu0.25Zn0.5 ferrite from microwave-induced combustion

Ni-Cu-Zn ferrite powders were successfully synthesized by microwave-induced combustion process. The process took only 15 min to obtain as-received Ni-Cu-Zn ferrite powders. The resultant powders annealed at different temperature and were investigated by differential thermal analysis/thermogravimetry, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and vibrating-sample magnetometer. The as-received powders showed the formation of cubic ferrite with a saturation magnetization (M-s) of 63 emu/g. The MS increased to 75 emu/g for the sample annealed at 700 degreesC for 2 h and the intrinsic coercive force (H-c) reached at 290 Oe. The toroidal specimen sintered at 950 degreesC for 4 h presents the optimum initial permeability of 528 and the maximum quality factor of 62. The high initial permeability and large quality factor were closely associated with a higher densification. (C) 2004 Elsevier B.V. All rights reserved.