Structural, Magnetic, and Optical Studies of Ni–Mg Ferrites Synthesized by Polyol Method

Magnesium and nickel-substituted ferrites belong to an important class of spinel ferrites with wide variety of applications. Herein, preparation and characterization of pure, single-phase Ni–Mg ferrites using a cost-effective method, which yield high-quality nanosized particles with good chemical homogeneity, are reported. A series of Ni_xMg_(1−x)Fe₂O₄ nanocrystalline powders (x = 1,0.75,0.5,0.25,0) is prepared using polyol method and a detailed investigation on the effect of dopant substitution on microstructural magnetic as well as optical properties is conducted. The as-prepared samples are subsequently characterized using X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Field-emission scanning electron microscope (FESEM), Brunauer, Emmett, and Teller (BET), Mossbauer spectroscopy, Vibrating sample magnetometer (VSM), and UV–visible diffuse reflectance spectroscopy. Rietveld refinement confirms the single-phase cubic structure with Fd-3m (227) space group of Ni_xMg_(1−x)Fe₂O₄ series. The cation distribution can be represented as [Mg_(1−x−y)Fe_(δ)]^A[Mg_(x)Ni_(y)Fe_(2−δ)]^BO₄. FTIR bands at the finger print region of ferrites and Mossbauer analysis confirms the proposed cation distribution from Rietveld refinement. The magnetic nature is confirmed from Mossbauer and VSM analysis. In VSM, the saturation magnetization of the samples exhibits an increasing trend with nickel substitution. The optical studies of the series Ni_xMg_(1−x)Fe₂O₄ are conducted by UV–visible diffuse reflectance spectroscopy.