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In the present study, Mg_xMn_1–xFe₂O₄ series of ferrites with x = 0.1, 0.3, 0.5, 0.7 and 0.9 were prepared by the citrate precursor technique. One set of samples was subjected to normal and the other to hot-pressed technique. Microstructural properties were studied with the help of X-ray diffraction (XRD) and scanning electron microscopy (SEM) for both sets of samples. Hot pressing of Mg–Mn ferrites results in an improvement of their magnetic and micro-structural properties, as it simultaneously controls grain growth and porosity. Hot pressing of Mg–Mn ferrites, however, results in deterioration of their dc resistivity. The cation distribution has been studied by X-ray analysis and magnetization. The variation of saturation magnetization and Curie temperature with increasing concentration of Mg²⁺ ions can be explained on the basis of cation distribution and Neel two sublattice models. Possible mechanisms, models and theories contributing to these results have been discussed.

La-doped and Cu-doped ZnO nanowires have been prepared to compare the substitution effect on the microstructural and magnetic properties. The XRD patterns of both compositions with single diffraction peak (002) show the same wurtzite hexagonal structure. The growth rate of the ZnO nanowires were enhanced by Cu doping, which were different from the suppression of growth rate by La doping. Room temperature ferromagnetism is observed for all ZnO, Cu-doped ZnO and La-doped ZnO nanowires. The saturation magnetizations are 0.102, 0.232 and 0.04 emu/g for ZnO, Cu-doped ZnO and La-doped ZnO nanowires, respectively. The results showed that the ferromagnetism is restrained by Cu doping, but enhanced by the La doping.

${\mathrm{\text{Ni}}}_{0.65-x}{\mathrm{\text{Mg}}}_x{\mathrm{\text{Zn}}}_{0.35}{\mathrm{\text{Fe}}}_2{\mathrm{\text{O}}}_4$ (x = 0, 0.4, 0.8, 0.10, 0.12 and 0.16) samples have been synthesized by sol–gel method using polyvinyl alcohol (PVA) as chelating agent. The synthesized samples were sintered at 1000${}^{\circ }$C for 1 h. The X-ray diffraction (XRD) confirms single phase spinel structure and scanning electron microscope (SEM) confirms the uniform grain with increasing grain growth with increase concentration of magnesium (Mg) (x). A slight increase in saturation magnetization (VSM) has been observed for low concentrations of magnesium which disappear for higher concentrations of magnesium $(x>0.12)$ in these materials. Decrease in room temperature DC resistivity with magnesium concentration has been attributed to grain growth. The permeability measured for the ferrites exhibits high permeability for increase in the magnesium content. The permeability behavior is understood on the basis of domain wall contribution and grain growth. Frequency dependence of permeability as measured suggests that the suitability of all the samples for high frequency core applications as the operating frequency lies beyond 110 MHz.

This paper studies the fabrication of a novel planar electromagnet consisting of a planar copper coil and a magnetic yoke. CoFeB was used as the magnetic yoke material instead of the traditional permanent magnets. The planar electromagnet was fabricated and optimized to maximize the electromagnetic force, especially with varying CoFeB thickness. The micro-planar electromagnet was fabricated successfully by the traditional micro-electro-mechanical-system (MEMS) techniques and XRD, VSM were used to characterize the performance of the electromagnet. The planar electromagnet exhibits superior perpendicular magnetic anisotropy (PMA) and 0.006 emu of $M_S$ was achieved following 2 min deposition of CoFeB thin film. By integrating with other micro apparatuses, it is anticipated that the planar electromagnet will have potential applications in areas such as biosensors, biological medicine, drug delivery, chemical analysis and environmental monitoring.

In this research, SrFe${}_{12-x}$Ni${}_x$O${}_{19}$ (x$=$ 0 − 1) hexagonal ferrites were prepared by sol-gel auto-combustion method. Effect of Ni substitution on structural, morphological and magnetic properties of nanoparticles was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), respectively. The XRD results confirmed that all samples with x$\le$ 0.5 have single phase M-type strontium ferrite structure, whereas for the SrFe${}_{12-x}$Ni${}_x$O${}_{19}$ samples with x$>$ 0.5, the spinel NiFe₂O₄ phase has also appeared. The lattice parameters and crystallite sizes of the powders were concluded from the XRD data and Williamson–Hall method. Magnetic analyses showed that the coercivity of powders decreased from 5672 Oe to 639 Oe while the saturation magnetization increased from 74 emu/g to 81 emu/g with nickel substitution. The results of this study suggest that the strontium hexaferrites doped with Ni are suitable for applications in high density magnetic recording media as well as microwave devices because of their promising magnetic properties.

Co(5 nm)/Dy(t${}_{\mathrm{\text{Dy}}}$)/Co(20 nm)/S and Ni(5 nm)/Dy(t${}_{\mathrm{\text{Dy}}}$)/Ni(20 nm)/S trilayer films are prepared by electron-beam sputtering to investigate the influence of dysprosium layer thickness (t${}_{\mathrm{\text{Dy}}}$) and thermal annealing on the crystal structure, magnetoresistance (MR) and magnetic properties of thin films. The thickness of Dy layer changed in the range from 1 nm to 20 nm. The samples annealed for 20 min at 700 K. Electron diffraction patterns reveal that the as-deposited and annealed systems Co/Dy/Co and Ni/Dy/Ni had fcc-Co + hcp-Dy and fcc-Ni + hcp-Dy phase state, respectively. It is also shown that at the t${}_{\mathrm{\text{Dy}}}$ = 15 nm the transition from amorphous to crystalline structures of Dy layer is observed. An increase in the Dy layer thickness results in changes in the MR and magnetic properties of the trilayer systems. It is shown that MR is most thermally stable against annealing to 700 K at t${}_{\mathrm{\text{Dy}}}$ = 15 nm for Co/Dy/Co as well as for Ni/Dy/Ni. For t${}_{\mathrm{\text{Dy}}}$ = 15 nm the, value of MR for both system increases by two times compared to those of pure ferromagnetic (FM) samples. The coercivity (B${}_c$), remanent (M${}_r$) and saturation (M${}_s$) magnetization of the in-plain magnetization hysteresis loops are related to the Dy layer thickness too. The coercivity depends on the FM materials type and diffusion processes at the layer boundary. Accordingly, M${}_r$ and M${}_s$ are reduced with t${}_{\mathrm{\text{Dy}}}$ increasing before and after annealing for both trilayer systems.

The magnetic properties of NiAl${}_x$Fe${}_{2-x}$O₄ (NAFO) spinels were studied. Influence of Al doping on magnetic properties of NiFe₂O₄ spinel were examined. The exchange interactions in NAFO were obtained. The general expression of saturation magnetization and the critical temperature were obtained using mean field theory. The high-temperature series expansions combined with the Padé approximant are given to determine the critical temperature of NAFO. The critical exponent associated with the magnetic susceptibility $\gamma$ was also deduced. The obtained results were in good agreement with magnetic measurement.

In this work, Fe₂N magnetic nanocomposite was synthesized via an in-situ reaction method of ball milling. In this method, Fe and h-BN were used as iron source and nitrogen source, respectively. We found that ball milling could increase the surface energy and make the sample to be amorphous, which is the key factor in synthesizing Fe₂N nanocomposite. The as-synthesized nano-sized Fe–N could disperse in the BN matrix uniformly. It is worth noting that we can obtain Fe₂N with different grain sizes by controlling the experimental conditions. The saturation magnetization of Fe₂N was measured and the value is about 0.03 emu/g. The excellent properties of Fe₂N magnetic nanocomposite suggest that Fe₂N magnetic nanocomposite could be widely used in industrial application.

Well-defined ZnO and Sm-doped nanorods have been successfully fabricated by a low temperature hyderthermal process. The XRD patterns of both compositions with single diffraction peak (002) show the same wurtzite hexagonal structure. The radius of Sm-ZnO nanorods observed by FE-SEM is smaller than that of pure ZnO indicating the reduction of growth rate by the doping of Sm. Ferromagnetism is observed from the results of magnetization measurement. The increase of the saturation magnetization and decrease of coercivity reveal an association with the increase of oxygen vacancies induced by the doping of the Sm in the nanorods.

The nano-crystalline iron nitride films with a mixture of γ-Fe₄N, εFe₃N and αFe₂N phases were synthesized on copper substrate by sol–gel technology. The structure, morphology and magnetic properties of the samples were characterized using X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer. The films are ferromagnetic at room temperature. Magnetic properties such as coercive forces and saturation magnetization were found to be 398 Oestered and 32.92 emu/cm³, respectively.

Sol–gel method has been employed to prepare Ni–Zn ferrite with chemical formula Ni${}_{1-x}$Zn_xFe₂O₄ where $x=$ 0, 0.1, 0.2, 0.3, 0.4 and 0.5. The structural Ni–Zn ferrite was studied via the X-ray diffractometer (XRD) pattern. X-ray analysis showed that there is a small shift in peaks towards shorter angles which increases with the concentration of zinc. Experimental values of lattice constant was varied from 8.34 of Ni ferrite to 8.397nm for Ni–Zn ferrite. The crystallite size of Ni ferrite was 83nm which is decreasing with substituted Zn to it and became 43nm at $4x=0.5$. Therefore, the superparamagnetic behavior appears with substitution of Zn to Ni ferrite. The saturation magnetization, remiensis, coersivity, magnetic moment and anisotropy constant were calculated according to hysteresis loop using the result of vibrating sample magnetometer (VSM). The effect of cation distribution appeared clearly through the saturation magnetization value which was 46.8emu/gm for nickel ferrite and increased to an optimum value (59.64emu/gm) at $x=0.3$.

ZnCr_1-xFe_xO₄ system (with x = 0, 0.5, 1, 1.5, and 2) at the nanoscale has been successfully synthesized by a simple combination of milling mixture of Zn, Cr, and Fe oxides precursors. X-ray diffraction and magnetic measurements were carried out on the as-milled powders. XRD pattern clearly shows that the mixed oxides are all nanosized. However, as Fe₂O₃ increases the ZnCrFeO₄ phase becomes the main phase. However, magnetic measurements do not show any significance in saturation magnetization (Ms), only when the content of Fe becomes 50% and 0.75% the Ms increased drastically to 15.4 and 16.7 emu/g respectively. However, with Fe 75% He and Mr reduced abruptly to half of their values, showing a ferromagnetic behaviour with low He.

The particulate composites with general formula (y)Ni_0.85Cd_0.1Cu_0.05Fe₂O₄ + (1 - y)BaTiO₃, (0.0 < y < 1.0) were synthesized by conventional double sintering ceramic technique. The formation of cubic spinel structure in ferrite phase and tetragonal perovskite structure in ferroelectric phase was confirmed by X-ray diffraction (XRD) measurements. The surface morphology with average grain size of the composites was studied by SEM measurements. The study of variation of dielectric constant with frequency (20 Hz to 1 MHz) shows dielectric dispersion behavior in the low frequency region and almost constant at high frequency region. The linear variation in a.c conductivity with frequency shows small polaron type of conduction mechanism in the composites. The vibrating sample magnetometer (VSM) was used to study the magnetic properties such as saturation magnetization and magnetic moment.

This paper analyzes the effects of additives on the properties of Iron oxide. The Iron oxide was synthesized using the co-precipitation method. The X-ray diffraction (XRD) peaks of resultant Iron oxide perfectly matched with JCPDS #860550 ($\alpha$ phase of Iron oxide / Hematite). The additives like Cobalt oxide, Nickel metal, Indium oxide and Tin metal with diverse properties procured in readymade forms were mechanically mixed with Iron oxide in 1:99, 3:97, 5:95 and 7:93 weight ratios, respectively. The XRD peaks for additives were prominent for 7:93 (Additive: Base Material) weight % ratio samples. Therefore, for further studies, only these samples were used. In this study, variations in XRD intensity, lattice parameters, unit cell volume, grain size, micro-strains (W-H analysis), dislocation density and stacking fault probability were analyzed. The specific surface area of particles was calculated by scanning electron microscope analysis. The presence of additives was also confirmed by energy dispersive spectra (EDS). The M-H loops (Vibrating Sample Magnetometer analysis) for samples under investigation showed rare vertical shifts. The weak magnetic behavior of bare Hematite (1.0 emu/gm) sample improved to antiferromagnetic behavior due to the addition of Cobalt oxide (7.89 emu/gm) and Nickel metal (2.76 emu/gm). The addition of Indium oxide (0.65 emu/gm) and Tin metal (0.73 emu/gm) samples showed a decreased magnetic saturation.

In this research, influence of adding Li₂CO₃ (at 0%, 2%, 4%, 6%) on electrical and magnetic properties of ${\text{Ni}}_{0.6}$${\text{Mg}}_{0.4}$Fe₂O₄ (with 60% Ni and 40% Mg) ferrite has been studied. The samples are prepared by solid state reaction method and sintered at 1300^∘C for 6h. X-ray diffraction (XRD) patterns show the samples belong to single-phase cubic structure without any impurity phase. The magnetic properties (saturation magnetization and coercivity) of the samples have been investigated by VSM and found that the higher concentration of Li₂CO₃ reduces the hysteresis loss. DC resistivity increases with Li₂CO₃ contents whereas it decreases initially and then becomes constant at lower value with temperature which indicates that the studied samples are semiconductor. The dielectric dispersion occurs at a low-frequency regime and the loss peaks are formed in a higher frequency regime, which are due to the presence of resonance between applied frequency and hopping frequency of charge carriers. Notably, the loss peaks are shifted to the lower frequency with Li₂CO₃ additions.

In this work, we used the modified Hummers method to synthesize graphene oxide, and the redox reaction of FeCl${}_3\cdot 6$H₂O with the carboxyl group on the surface of acidified graphene was carried out to prepare magnetic nanoparticles modified on the surface of graphene (magnetic graphene nanocomposite). X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Vibrating Sample Magnetometer (VSM) and Brunauer–Emmett–Teller measurement (BET) analyses were used to characterize the nanocomposite properties. SEM and TEM images of the nanocomposite show that the magnetic nanoparticles are distributed on both sides of the graphene, and the magnetic nanoparticles diameter is between 100 and 150nm. The XRD pattern indicates that the magnetic nanoparticles are Fe₃O₄ nanoparticles. Based on the VSM, the nanocomposite exhibits a saturation magnetization value of 14.94$\mathrm{\text{emu}}\cdot {\mathrm{\text{g}}}^{-1}$. By BET measurement, the specific surface area of the nanocomposite is 26.54m${}^2\cdot {\mathrm{\text{g}}}^{-1}$, and the surface of the nanocomposite is highly porous. In the experiment of dyes adsorption, the adsorption efficiency in the solution was close to 100%. It can be applied in biomedical and environmental fields such as water purification owing to its high surface, magnetic attraction properties and good adsorption efficiency.