Evaluation of the Morphology and Magnetic Properties of Cr3+ - Doped Ni-Zn Ferrites

This work involved a morphological, microstructural and magnetic characterization of nanosized powders and sintered samples of Ni-Zn ferrite doped with chromium. The effect of substituting Fe3+ for Cr3+ on the final characteristics of the powders and sintered samples was investigated. The Ni-Zn ferrite powders were prepared by combustion reaction using nitrates and urea as fuel, based on the concepts of propellant chemistry. The samples were uniaxially compacted by dry pressing (385 MPa) and sintered at 1200 degrees C/2h, using a heating rate of 5 degrees C/min. The Ni-Zn powders and compacted samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and the measures of their magnetic properties. The results revealed the formation of the cubic crystalline phase of the inverse spinel of Ni-Zn-Cr ferrite. The average crystallite size was 21 nm and 57 nm while the saturation magnetization was 47.0 and 73.1 emu/g for the powder and the sintered sample, respectively.