Magnetic, electrical, and structural properties of Mg2+-doped nickel-zinc ferrite prepared by sol-gel-SHS method

Magnesium-substituted Ni-Zn ferrite (Ni0.5Zn0.5-xMgxFe2O4, x = 0-0.3, in steps of 0.05) has been successfully synthesized via a sol-gel-SHS (self-propagating high-temperature synthesis) method. The Fourier transform infrared spectra indicate the formation of spinel structure for Ni-Mg-Zn ferrites by sol-gel-SHS method. Thermogravimetric analysis reveals that the lowest decomposition temperature of SHS powder is approximately 400 degrees C. X-ray powder diffraction results signify a single-phase nature of cubic spinel structure for these samples without any detectable impurity phase. Lattice constant gradually decreases as the magnesium content continuously increases, while the average crystallite size increases except for undoped sample. Scanning electron microscopy images demonstrate that the samples consist of regular shaped grains without any phase segregation and agglomeration. Magnetization measurements indicate that all samples display a typical soft ferromagnetic characteristic with an abnormal saturation magnetization peak at x = 0.15. The frequency dependence of dielectric constant of the synthesized Ni-Mg-Zn ferrite exhibits a normal dielectric behavior, while the dielectric loss shows an abnormal peak behavior. The modulation mechanism for magnesium-substituted Ni-Zn ferrite on structure, electrical, and magnetic properties is systematically discussed.