Saturation Remanence Research Articles

Improved magnetic properties of Sr0.93Sm0.10Fe11.97O19/Fe3O4 composite powders by substitution of Sm and magnetic exchange coupling effect

M-type hexagonal Sr0.93SmxFe12.07−xO19 and Sr0.93Sm0.1Fe11.97O19/Fe3O4 (SSFO/Fe3O4) composites are prepared by the ball-milling-assisted ceramic process and the solvothermal method, respectively. Substitution of Fe3+ ions by Sm3+ ions can significantly enhance the specific saturation magnetization (Ms), remanence (Mr), and coercivity (Hc) of Sr0.93SmxFe12.07−xO19. Increase in coercivity is attributed to an increase in the magnetrocrystalline anisotropy and a reduction in the particle size after substitution of Fe3+ ions by Sm3+ ions. Sr0.93Sm0.10Fe11.97O19 has the highest specific saturation magnetization value (71.16 emu/g). By contrast, 2.91% increase in specific saturation magnetization and 22.86% increase in coercivity for SSFO/Fe3O4 composite with 4:1 mass ratio of hard to soft ferrites are observed, respectively, as compared to the pure SSFO. Besides, SSFO/Fe3O4 composite with 4:1 mass ratio of hard to soft ferrites behaves higher Mr (33.80 emu/g) and Hc (2624.27 Oe) values than theoretically calculated values of 30.60 emu/g and 1722.72 Oe, indicating the presence of strong exchange coupling interaction between the hard SSFO and soft Fe3O4 phases.

Surface Modification of Magnetic Mesoporous Systems with Aminopropyl Groups and Their Properties

Iron oxide silica FexOy-SiO2 composite systems with aminopropyl (AP) groups on the surface have been synthesized via different routes. The surface modified samples have been studied by X-ray diffraction (XRD) analysis and IR spectroscopy. Magnetic phases of iron oxides have been detected after post-synthetic grafting of AP groups onto the surface of these composite systems. Magnetic properties of these samples have been determined. Only insignificant reduction in the material saturation magnetization and remanent magnetization have been registered upon surface grafting procedure. This approach has been considered to be successful as magnetic properties of the substrate were preserved. Amount of aminoalkyl groups grafted onto the silica composite surface has been determined by thermogravimetric analysis. The mass fraction of grafted aminoalkyl groups has been found to be dependent on the textural properties of the composite sample.

Structural and Magnetic Properties of Nickel Ferrite Nanoparticles Prepared by Solution Combustion Method

Nickel ferrite nanoparticles with chemical formula NiFe2O4 were prepared by standard sol-gel auto ignition technique. Citric acid was used as chelating agent and mixed with solution of nickel nitrate and ferric nitrate in 3:1 proportion to balance the oxidizer to reducer ratio. The obtained particles were sintered at 550°C for 4h to remove the water content, impurity and to obtain better crystallinity. The phase purity and structural formation was confirmed through the analysis of X-ray diffraction technique. The results of X-ray diffraction analysis show the single phase cubic spinel nanocrystalline structure. The particles size calculated from FWHM of the strongest peak (311) is 22 nm in the nanometer dimension. The lattice constant, X-ray density and other structural parameters calculated from XRD data are in good agreement with the literature values. The magnetic measurements were taken at room temperature using hysteresis loop technique. Using M-H plot, the different magnetic parameters such as saturation magnetization, coercivity, remanence magnetization and magneton number were deduced.

X-ray Diffraction, Infrared and Magnetic Studies of NiFe2O4 Nanoparticles

Spinel ferrite nanoparticles plays important role in many applications due to their excellent structural, magnetic and electrical properties. Among the spinel ferrite nickel ferrite is a prominent candidate for various applications and is the subject of interest to many researchers. Therefore, attempt is made to synthesize NiFe2O4 nanoparticles and investigate its structural, infrared and magnetic properties for high frequency applications. NiFe2O4 nanoparticles were synthesized by sol-gel auto-ignition technique. Efforts are made to obtain nanopowder of high quality by taking extra care and some modification in synthesis procedure. In order to examine the phase purity and nanocrystalline nature, prepared nanopowder was subjected to X-ray diffraction studies. A close examination of XRD pattern revealed the presence of the reflections belonging only to cubic spinel structure. No extra peak was seen in the XRD pattern. The crystallite size was estimated using Debye-Scherrer’s formula and found to be 22nm. FT-IR spectrum of NiFe2O4 shows the two prominent absorption bands near the frequency range 400 cm−1 and 600 cm−1. The important magnetic property was studied by M–H plot which was recorded using pulse field hysteresis loop tracer at room temperature. Using the M-H plots the values of saturation magnetization, coercivity, and remanence magnetization are recorded as 37.61 emu/g, 177 Oe, and 11.71 emu/g respectively. The obtained data for structural and magnetic properties will be useful for high frequency applications.

Effect of cerium on structural, microstructural, magnetic and humidity sensing properties of Mn–Bi ferrites

In this report novel material Cerium doped Mn–Biferrite nanoparticles were synthesized by adopting a modified solution combustion route. X-ray diffraction patterns confirm the spinel cubic structure with single phase having space group Fd3m. The crystallite size decreases with increase in Ce3+ concentration. The scanning electron microscopy (SEM) micrographs show that the particles are agglomerated. The humidity sensing properties were investigated through resistance measurements, sensing response, recovery time, hysteresis and stability studies measurements. As per investigation the resistance decreases with increase in relative humidity from 11% to 97%. The sensing response values increases with increase in Ce3+ concentration. The response and recovery time study reveals the sample have quick response and recovery time. The magnetic hysteresis curves revealed that synthesized samples exhibits ferrimagnetic nature, the saturation magnetization and remanent magnetization decreases with the increase in Ce3+ concentration. Hence synthesized materials are good candidate for humidity sensor applications.

Nickel-Doped Cobalt Zinc Ferrites Co0.8 – xNixZn0.2Fe2O4 (x = 0.0–0.56) by Solid-State Reaction: Synthesis and Characterization

Cobalt zinc ferrite and Ni-doped cobalt zinc ferrites Co0.8 – xNixZn0.2Fe2O4 (x = 0.0, 0.08, 0.16, 0.24, 0.32, 0.40, 0.48, 0.56) were prepared through low-cost solid-state reaction. The process and products were characterized by TG/DTA, XRD, SEM, FTIR, and VSM. For synthesized ferrites, the values of saturation magnetization, retentivity, coercivity, remanence ratio, and magnetic anisotropy are reported.

Magnetic Properties of Nickel Ferrite Magnetic Nanoparticles Prepared via Glycine Assisted Sol-Gel Auto Combustion Route

The present research paper deals on the synthesis of nickel ferrite (NiFe2O4) nanoparticles using sol-gel auto combustion technique in which glycine was used a chelating agent. The prepared nanoparticles were annealed at 500°C for 4 h. and then used for structural, magnetic and other investigations. The X-ray diffraction technique was used for phase purity and structural determination. Room temperature X-ray diffraction pattern of NiFe2O4 nanoparticles shows all the reflections belonging to cubic spinel structure. The reflections are intense and slightly broader. No extra peak other than cubic spinel structure was observed in the XRD pattern. This indicates the single phase formations of the nickel ferrite nanoparticle. The refinement of XRD data has been carried out by using full proof programmer. The lattice constant was calculated using XRD data as well as Cohen’s least square method, the obtained lattice constant matches with the reported value. The other structural parameters like lattice strain, X-ray density etc. structural parameters were also calculated using standard relations. The crystallite size was determined using Scherrer’s formula in which the most intense peak (311) was considered. The crystallite size was found to be 24 nm which indicates the nanocrystalline nature of the prepared nickel ferrite nanoparticles. The magnetic properties of were investigated using the pulse field hysteresis loop (PFHL) technique at room temperature. The saturation magnetization, coercivity and remanence magnetization shows enhanced values. All the structural and magnetic properties results were compared with the reported data in which other chelating agent like citric acid etc.

Nano‐Magnetite Aggregates in Red Soil on Low Magnetic Bedrock, Their Changes During Source‐Sink Transfer, and Implications for Paleoclimate Studies

AbstractSoil and lake sediments are important paleoclimate archives often forming a source‐sink setting. To better understand magnetic properties in such settings, we studied red soil on low‐magnetic bedrock and subrecent sediments of Caohai Lake (CL) in Heqing Basin, China. Red soil is the only important source material for the CL sediments, it is highly magnetic with susceptibilities (χ) of ~10−5 m3/kg. The red soil is dominated by pedogenic nano‐magnetite (~10–15 nm) arranged in aggregates of ~100 nm, with particle interaction that causes a wide effective grain size distribution in the superparamagnetic (SP) range tailing into stable single‐domain behavior. Transmission electron microscopy and broadband frequency χ(f) suggest partial disintegration of the aggregates and increased alteration of the nanoparticles to hematite during transfer of red soil material to CL. This shifts the domain state behavior to smaller effective magnetic grain sizes, resulting in lower χfd% and χ values, and a characteristic change of χ(f). The SP‐stable single‐domain distribution of the aggregates in red soil could be climate dependent, and the ratio of saturation remanence to χ is a potential bedrock‐specific paleoclimate proxy reflecting it. Magnetic properties of the CL sediments are controlled by an assemblage of nanoparticle aggregates and larger‐sized bedrock‐derived magnetite. The results challenge the validity of the previous paleoclimate interpretation from the 168‐m‐long Core‐HQ (900–30 ka) in Heqing Basin. Disintegration of aggregates could lead to SP behavior with low χfd% without extinction of individual magnetite nanoparticles, and the χfd%‐based assumption of SP magnetite dissolution may be wrong.

Structural, ferromagnetic, electrical, and dielectric relaxor properties of BaTiO3 and CoFe2O4 bulk, nanoparticles, and nanocomposites materials for electronic devices

Barium titanate (BaTiO3, BTO) and cobalt ferrite (CoFe2O4, CFO) nanoparticles, bulk, and nanocomposites samples were synthesized at optimized parameters using the chemical route. Structural studies revealed that all the samples showed a single-phase structure. The value of activation energy in the case of nanocomposites was 975 meV, while it was 1.58 eV and 1.0 eV for BTO and CFO-nanoparticles, respectively. We observed that the saturation magnetization and remanence of the CFO-nano sample were three times greater than the 0.3CFO–0.7BTO nanocomposite. At 10 kHz, the dielectric constants are measured 4500 (BTO-bulk), 1550 (BTO-nano), 820 (CFO-bulk), 275 (CFO-nano), and 375 (BTO–CFO nanocomposites) for a various sample of series. We found at 10 kHz, the transition from ferroelectric to paraelectric in the case of BTO-nano (Tc = 363 °C) and CFO-nano (Tc = 212 °C), while nanocomposite BTO–CFO initial change phases from ferroelectric to anti-ferroelectric (relaxor behavior) at Td = 312 °C and then from anti-ferroelectric to paraelectric (Tm > 400 °C). Similarly, in the case of CFO-bulk, we noticed Tm = 204 °C (ferroelectric to anti-ferroelectric) and Tm = 314 °C (anti-ferroelectric to paraelectric). Overall, we concluded from these studies and data that nanocomposite 0.7BaTiO3–0.3CoFe2O4 and CFO-bulk sample showed relaxor behavior as well along with the transformation change from ferroelectric to paraelectric. While BTO-nano and CFO-nano and BTO-bulk showed their transformation direct from ferroelectric to paraelectric. These simultaneous ferromagnetic and ferroelectric (dielectric) measurements confirmed the presence of multiferroic properties in our nanocomposite as well as CFO-nano and CFO-bulk systems. These proposed materials may be useful for ferroelectric and data storage devices.

Comparative study of tensile properties and magnetic properties for Nb-doped Fe-based wires

Herein, the comparative study of tensile and magnetic properties of Fe-based wires formed by rotated-dipping process before and after Nb-doping has been reported. In which, the phase composition, crystallization temperature, surface and fracture morphology, and magnetic performance are respectively investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and Physical Property Measurement System (PPMS), respectively. Further, the experimental results indicate that the Nb-doped Fe-based wires show an amorphous state, uniform, and continuous, with excellent glass forming ability (GFA) and thermal stability. The saturation magnetization Ms and remanent magnetization Mr decrease owing to Nb-doping, while the coercivity Hc shows an increasing trend with the rising of Nb-doping, reaching 33.0 Oe. The tensile deformation process of Nb-doped Fe-based wires is mainly elastic deformation, reflecting the brittle fracture characteristics. While the Nb-doping can effectively enhance the tensile strength Rm of Fe-based wires, and the Rm of FeSiBNb3 wires exhibits the maximum value of 3.58 GPa. Moreover, the fracture morphology takes on the massive shear bands, and the fracture angles are about 45°, there are also some vein-shaped patterns and molten drops, even the fracture reliability analysis based on the statistical theory of Weibull mechanics indicates that the Nb-doped Fe-based wires possess an obviously improved fracture reliability. Therefore, it can be concluded that the Fe-based wires with improved tensile and magnetic properties as the candidates are adopted for potential electromagnetic and mechanical engineering applications.

Structural, Microstructural, Electrical, and Magnetic Properties of CuFe2-(x+y)EuxScyO4 (where x and y vary from 0 to 0.03) Nanoparticles

In the present work, the CuFe2-(x+y)EuxScyO4 nanoparticles were prepared by solution combustion method for reporting the structural, microstructural, dielectric, and magnetic properties of prepared samples. The XRD (X-ray diffractometer) patterns confirm the spinel cubic structure with space group Fd3m. The average crystallite size was found in the range from 25 to 10 nm for x = y = 0.00, 0.01, 0.02, and 0.03 concentrations. The SEM (scanning electron microscopy) investigations indicate the porous nature and particle agglomeration. The elemental composition of the samples was studied by using energy-dispersive X-ray spectroscopy (EDS). The FTIR (Fourier transform-infrared spectroscopy) investigation shows the two absorption bands around 554.07 cm−1 and 468.98 cm−1 due to stretching vibrations of the Cu⟺O metal-oxygen bond at the A-site and stretching vibrations of Fe⟺O metal-oxygen bond at the B-site, respectively. The real and imaginary parts of dielectric constant, dielectric loss tangent, AC conductivity, and impedance spectroscopy have been recorded by the methods of impedance analyzer from the range 0.1 KHz to 1 MHz. The dielectric constant and dielectric loss show maximum value at smaller frequency region and are decreases with increase in frequency. AC conductivity increases with the increase of frequency. The real and imaginary part of impedance spectra as function of frequency was studied. The Cole-Cole plots drawn from the impedance spectra show one semicircle for each of the samples. The magnetic hysteresis loop reveals the soft ferromagnetic nature. The magnetic parameters such as saturation magnetization, coercivity, and remanence magnetization decrease with the increase of Eu3+ and Sc3+ concentration.

Synthesis, Electric and Magnetic Characterization of Nickel Ferrite/PANI Nano-Composite Prepared by Flash Auto Combustion Method

NiFe2O4/PANI nano-composite with different polyaniline (PANI) content (25%, 50% and 75%) is synthesized. The NiFe2O4 (NF) is prepared by the flash auto combustion method and annealed at 400 °C for 2 h. The PANI is prepared by oxidative polymerization of aniline. The X-ray diffraction (XRD) technique confirmed that the NiFe2O4 particles are successfully dispersed in the PANI matrix with single phase structure. The characteristic absorption bands are observed from infrared (IR) spectra for the pure NF, pure PANI and their nano-composite. The dielectric constant ( $${\varepsilon }^{^{\prime}})$$ behavior of NF/PANI nano-composite at higher PANI content tends to be a polymer behavior. The Curie temperature decreased by increasing the PANI content and it is attributed to the basis of A-B exchange interaction due to the variation of $${Fe}^{3+}$$ content among the octahedral and tetrahedral sites. The values of the saturation magnetization (Ms), remanence magnetization (Mr), coercivity (Hc), area and squareness (Mr/Ms) are measured by using a vibrating sample magnetometer (VSM).

Chemical modification of carboxylated MWCNTs for enhanced electrical conducting and magnetic properties

An electrical conducting and magnetic nanomaterial, [Ni(II)Hyd]-MWCNTs was synthesized via chemical modification of carboxylated MWCNTs (A-MWCNTs). The synthesized material has been studied by FTIR, UV–Visible, XPS, Raman, TGA, powder XRD, TEM and EDAX analysis. Double probe DC conductivity suggested enhanced electrical conductivity of [Ni(II)Hyd]-MWCNTs compared to A-MWCNTs. (RsQ(RctO)) is found to be best fit Randle’s equivalent circuit. The positive slope obtained from Mott-Schottky plot suggested n- type semiconducting behavior of materials. The positive shift in flat-band potential for [Ni(II)Hyd]-MWCNTs is the signature of its more conducting nature than that of A-MWCNTs. The better conductivity of [Ni(II)Hyd]-MWCNTs is also confirmed by optical and electrochemical band gap studies. The field and temperature dependent magnetization revealed intrinsic ferromagnetism in [Ni(II)Hyd]-MWCNTs with enhanced saturation magnetization, remanent magnetization and coercivity values compared to A-MWCNTs. Hence, high electrical conductivity and magnetic properties prompt the [Ni(II)Hyd]-MWCNTs for applicability in spin-based electronic devices and in other application such as EMI shielding, metamaterials, drug delivery, anticorrosion, etc.

Single Phase Oxidation of Ferrimagnetic Grains as a Cause of L-Shaped Arai–Nagata Diagrams

Abstract—The experiments on the determination of paleointensity Banc of the Earth’s magnetic field by Thellier method on basalts of the Berd (Jurassic) and Paravakar (Cretaceous) collections sampled in the northeastern Armenia in 2006 revealed an anomalous behavior of the Arai–Nagata diagrams. The anomaly manifests itself by a sharp drop in the intensity of natural remanent magnetization (NRM) under heating of samples to about 400°C, which is accompanied by a very weak acquisition of partial thermoremanent magnetizations (pTRMs) in this temperature interval. The further increase in temperature leads to the opposite phenomenon—an unexpectedly sharp rise in pTRMs intensity with almost no decrease in NRM, which creates the L-shape of the Arai–Nagata diagram. A similar phenomenon of a steep decline during thermal demagnetization was also established for remanent saturation magnetization Mrs(T). We carried out a number of magnetomineralogical experiments from which we conclude that, consistent with the hypothesis suggested by (Kosterov and Prevot, 1998), the sharp drop in Mrs(T) and NRM(T) curves is caused by the transitions of the domain state from a metastable configuration to a more stable one. These transitions are initiated by the processes of single- and heterophase oxidations of primary titanomagnetites under the laboratory heating of samples to moderate temperatures.

Effect of chromium ions on the structural, magnetic, and optical properties of manganese–zinc ferrite nanoparticles

The present work describes the synthesis of Mn0.5Zn0.5CrxFe2−xO4 (x = 0.1, 0.2, 0.3) ferrite nanoparticles by solution combustion method and their detailed structural, electrical, magnetic, and optical characterizations. X-ray pattern represents the creation of a single spinel structure. In addition to this, the distribution of cations is also approximated from X-ray study which is then authenticated by the magnetization technique also. The crystalline size (23–21 nm) and lattice parameter (8.39–8.30 A) are found to shrink with the rise in chromium ions. A decrease in saturation magnetization (0.80–0.64 emu/g) and remanent magnetization (0.05–0.03 emu/g) is found with the rise in chromium ions, while the coercivity is found to increase (83–123 Oe) through the adding of chromium ions. FTIR predicted the two absorption bands (ν1 and ν2) near 600 and 400 cm−1. Dielectric constant and loss tangent were observed to decrease with an increase in frequency, whereas AC conductivity attains a nearly constant value at a lower frequency and observed to increase at higher frequencies with the addition of dopant.

A Study of Magnetic Properties of Manganite Substituted ZnFe2O4 Composites

Composites of ZnFe2O4/La0.67Sr0.33MnO3 with different weight percentages were synthesized using sol-gel method and their magnetic behavior was investigated. Powder X-ray diffraction studies show spinel structure for zinc ferrite and rhombohedral for La0.67Sr0.33MnO3. An additional minor phase of α −Fe2O3 and ZnO was also noticed in zinc ferrite suggesting non-stoichiometric nature. Fourier transform infrared spectroscopy studies display cohabitation of two phases belonging to ferrite and perovskite phase with varying peak intensities. Field-dependent magnetization measurement at room temperature shows partial variation in saturation magnetization and remanent magnetization values with increase in La0.67Sr0.33MnO3 weight percent in zinc ferrite. Except for zinc ferrite, $\left (\frac {dM}{dH}\right )$ shows single peak with smooth variation, pointing to easy rotation of magnetic dipoles under applied fields.

Effect of amorphous SiO2 matrix on structural and magnetic properties of Cu0.6Co0.4Fe2O4/SiO2 nanocomposites

This study presents the structural and magnetic characterization of αCu0.6Co0.4Fe2O4/(100-α)SiO2 (α = 0, 25, 50, 75 and 100%) nanocomposites prepared by sol-gel method, followed by thermal treatment at 200, 500, 800 and 1200 °C. The SiO2 matrix was found to be amorphous. At low ferrite contents, the obtained Cu–Co ferrite is unpurified by crystalline CoO, while at high ferrite contents single-phase Cu–Co ferrite is obtained. The particle sizes increase from 30 to 120 nm with increasing ferrite content embedded in the SiO2 matrix, while the crystallinity increases at higher thermal treatment temperature. The atomic force microscopy revealed the morphology of the Cu0.6Co0.4Fe2O4/SiO2 nanocomposites. For samples treated at 200 and 500 °C, the specific surface area increases and the crystallinity decreases with increasing SiO2 content. For all samples, the surface area decreases with the increasing annealing temperature. The SiO2 matrix is diamagnetic and does not show hysteresis curve. The saturation magnetization and remanent magnetization improved, while the coercivity and magnetic anisotropy decreased with increasing Cu–Co ferrite content embedded in SiO2 matrix.

Influence of graphene on the magnetic properties of nickel ferrite nanoparticles

Nickel ferrite nanoparticles were subjected to mechanochemical activation for ball milling times ranging from 0 to 12 h. The milling was performed with and without the addition of equimolar concentrations of graphene nanoparticles. Characterization of resulting nano-powders was undertaken by Mӧssbauer spectroscopy and magnetic measurements. The hyperfine magnetic field was studied as function of milling time for octahedral and tetrahedral sites. An additional quadrupole split doublet represented the occurrence of superparamagnetic particles in the as-obtained and milled specimens. A new phase was obtained in the graphene-milled set of samples, which could be assigned to carbon-rich particles. The degree of inversion and canting angle were derived from the Mӧssbauer measurements and studied as function of ball milling time. The degree of inversion was found to decrease with milling time, especially for the set without graphene and evidenced a transition from inverse to normal spinels. The canting angle decreased with time for the graphene milled nanoparticles. The recoilless fraction was determined as function of milling time and was consistent with the observation – for the first time in literature – of a distribution of recoilless fractions in the studied specimens. The saturation magnetization, remanence magnetization and coercive field were derived from the hysteresis loops, recorded at 5 K and 5 T. The zero-field-cooling-field-cooling measurements were obtained in a magnetic field of 200 Oe and the blocking temperature was determined. Our results show new features of the behavior of nickel ferrite nanoparticles under mechanochemical activation with and without graphene.

Enhanced humidity sensing and magnetic properties of bismuth doped copper ferrites for humidity sensor applications

In present investigation, the CuFe(2-x)BixO4 (where, x = 0.00, 0.01, 0.02, 0.03) nanoparticles synthesized by solution combustion technique using mixture of fuels as glucose and carbamide. The refined XRD (X-ray diffraction) patterns of the samples confirms the spinel cubic structure having space group Fd3m. The average crystallite size was found to be in nanometer. The lattice parameter, volume, strain and hopping lengths were estimated. TEM (Transmission Electron Microscopy) micrographs confirm the particles are agglomeration. SAED (Selected Area Electron Diffraction) pattern reveals the polycrystalline nature of the material. The magnetic nature of spinel ferrite can be explained by Neel’s two sub-lattice model. In the present work, the observed decrease in magnetization can be ascribed to occupancy and migration of cations at/from B sites by the substitution of Bi3+ ions. The magnetic parameters such as saturation magnetization, remanent magnetization (Mr), coercivity field (Hc), remanence (S), uniaxial anisotropy (Ku) and cubic anisotropy (Kc) were estimated. The resistance and humidity sensing responses increases with increase of the Bi3+ concentration. The hysteresis curves reveal the desorption process is somewhat slower than the adsorption process. The sensing response time 73 s was recorded when sample was moved from 11% RH to 97% RH and the recovery time 36 s was recorded when sample was moved from 97% RH to 11% RH. The humidity sample shows exceptionally stable response at relative humidity 99% RH and 33% RH.

Enhancement of magnetic properties of Ni–Mg–Co ferrites by Y3+ ions doping

In this study, yttrium ion-doped nickel–magnesium–cobalt ferrite powder was prepared by the sol–gel auto combustions method. The chemical formula is Ni0.2Mg0.1Co0.7Fe2–xYxO4 (where x = 0.00, 0.02, 0.04, 0.06, and 0.08). The structure and magnetic properties were studied by X-ray diffractometer (XRD), Fourier infrared spectroscopy (FTIR), ultraviolet–visible (UV–Vis), scanning electron microscope (SEM), and vibrating sample magnetometer (VSM). XRD measurements show that Ni–Mg–Co ferrite has a good phase formations, and all samples have single-phase cubic spinel structure. As the doping amount of yttrium ions increases, the lattice constant of the samples increases first and then decreases. FTIR measurements also confirm the formations of the cubic spinel structure of ferrite. The UV–Vis optical analysis shows that the bandgap value of optical energy decreases after doping Y3+ ions. SEM confirmed that the sample was spherical spinel with a particle size of 54–60 nm. The saturation magnetizations (Ms) and remanent magnetizations (Mr) increase first and then decrease with the increase of Y3+ ions content at room temperature. This shows that the small amount of Y3+ ions-doped nickel–magnesium–cobalt nanoferrite can optimize the magnetic properties of the ferrite. The coercivity of the samples also showed a downward trend. The comprehensive measurement data show that the sample has the best magnetic properties when x = 0.02. This is also confirmed that the ferrite can be used as magnetic storage material.