Nanoferrites of nickel doped with cobalt: Influence of Co super(2+) on the structural and magnetic properties

Nanoferrites of nickel substituted with cobalt of composition Ni sub(1-x)Co sub(x)Fe sub(2)O sub(4) (0 [< or =] x [< or =] 0.75), were synthesized by combustion reaction assisted in microwaves. The influence of the substitution of Ni super(2+) by Co super(2+) content and the concentration of Co super(2+) in the structural and magnetic properties was investigated. The powders were prepared by combustion according to the concept of chemical propellants and heated in a microwave oven with a power of 7000 kW. The synthesized powders were characterized by absorption spectroscopy in the infrared region (FTIR), X-ray diffraction (XRD) together with Rietveld refinement, surface area (BET) method, scanning electron microscopy (MEV) and magnetic measurements (MAV). The results indicated that it was possible to obtain nickel ferrite doped with cobalt in all compositions and that an increase of cobalt concentration caused an increase in particle size (9.78-21.63 nm), a reduction in surface area, and reduction in magnetic concentrations greater than 50%.