Characterization of nanocrystalline NiCuZn ferrite powders synthesized by sol–gel auto-combustion method

The ferrite compositions Ni0.8−xCu0.2ZnxFe2O4 with x = 0.5, 0.55 and 0.6, were synthesized through nitrate–citrate gel auto-combustion method. The autocatalytic nature of the combustion process has been studied by thermal analysis (DTA and TG) of the dried gels. The powders were calcined at 700 °C/2 h and then pressed ferrite parts were sintered at 900 °C/4 h. The ferrite was characterized with respect to phase identification, crystallite size and lattice parameter determination using X-ray diffraction. As-burnt powders showed the presence of crystalline cubic spinel ferrite with about 19–22 nm crystallite sizes. The densification characteristic of the powder was investigated using TMA. The sintered ferrite was characterized for permeability, saturation magnetization, relative loss and ac resistivity measurements. The permeability and magnetization were found to increase and magnetic loss, ac resistivity were decreased with Zn substitution for Ni. The powder is suitable for the application in multilayer chip inductor due to its low temperature sinterability, good magnetic properties and low loss at high frequency.