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

Abstract

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 NixMg(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 NixMg(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 NixMg(1−x)Fe2O4 are conducted by UV–visible diffuse reflectance spectroscopy.

Hematene Nanoflakes: A non-van der Waals material with superior nonlinear optical properties

“…Figures 3(b Additionally, a peak can be observed at 30° which can be attributed to the reflection from the (220) plane suggesting a small amount of γ -Fe2O3 (JCPDS card 39-1346) in the sample. The approximate amount of the γ-phase in the sample is estimated to be 17 % from the XRD pattern using the intensities of the peaks using the equation [47] % 𝑜𝑜𝑜𝑜 𝛾𝛾 − 𝐹𝐹𝐹𝐹 2 𝑂𝑂 3 = 𝑑𝑑 𝛾𝛾 𝑑𝑑 ℎ𝑒𝑒𝑒𝑒 +𝑑𝑑 𝛾𝛾 (5) where 𝐼𝐼 𝛾𝛾 is the intensity of γ -Fe2O3 peak and 𝐼𝐼 ℎ𝑒𝑒𝑒𝑒 is the sum of intensities of all peaks of hematene nanoflakes in the XRD pattern.…”

Dielectric and electrochemical performance of rhombohedral lanthanum manganite perovskite nanostructures

“…32 No other impurity peaks can be seen in the diffractograms, suggesting the high purity of the samples. The average crystallite size ( L ) of the samples was estimated using the Scherrer formula 28 where K is a constant (0.89), λ is the wavelength of the X-ray used (1.54 Å), β is the full-width at half-maximum and θ is the diffraction angle.…”

“…34 The dislocation density ( ρ ) is a microstructural characteristic that results from an imperfection in a crystal associated with inaccurate lattice alignment. It is the reciprocal of the square of the crystallite size as given by the equation 28 The Goldschmidt tolerance factor ( t ) can be used to estimate the crystal structure. It is given by the equation 9 where R A , R B and R O are the ionic radii of the A-site, B-site and oxygen, respectively.…”

“…The Kubelka–Munk function derived from the reflectance data was used to calculate the energy bandgap. Kubelka–Munk function F ( R ) is defined by the equation 28 where R is the reflectance measured. The direct bandgaps of all the samples were calculated from the plots of [ F ( R ) hν ] 2 versus ( hν ).…”

“…They found that the dielectric properties of nanopetals, dendrites and nanorods were better than those of nanospheres. Recently, Lekshmi et al 28 studied the dielectric properties of LaMnO 3 , LaFeO 3 and LaFe 0.9 Mn 0.1 O 3 , and found that among all three samples LaMnO 3 showed a high value of dielectric loss. Although there have been many such studies based on LaMnO 3 nanostructures, only a few studies are on the preparation of the stable rhombohedral phase of this material, which lack detailed investigation and optimisation of the formation of this material that has recently emerged as a potential supercapacitor electrode.…”