Spinel Ferrite Structure Research Articles

Reitveld Refinement and Derivative Spectroscopy of Nanoparticles of Soft Ferrites (MgNiFe)

MgNi ferrite nanoparticles were synthesized using an aqueous sol-gel method for targeted drug delivery and other electronic applications. The nitrates of Mg, Ni and iron were used as precursors and citric acid as fuel in a water based synthesis. The nanoparticles so prepared were characterized using X-ray diffraction technique (XRD), field emission scanning electron microscopy (FESEM); transmission electron microscope (TEM), vibrating sample magnetometer (VSM), FTIR spectroscopy and their respective derivatives. The results of XRD patterns are indicative of formation of ferrite nanoparticles and crystallite sizes were obtained using Williamson-Hall plot. Reitveld refinement was applied to assure about the crystal structure and allied parameters. The magnetic analysis of the prepared samples have been performed by VSM and found that the synthesized nanoparticles exhibited nearly superparamagnetic behaviour having high magnetic saturation (Ms) and negligible coercivity (HC). The FTIR plots confirm the formation of spinel structure of the MgNi ferrites. The formation of spinel ferrite structure is confirmed by absorption bands corresponds to vibration of tetrahedral (A) site and by absorption bands corresponds to the octahedral (B) site. Reitveld refinement and derivative spectroscopic analysis give detailed analysis from XRD, VSM and FTIR studies and helps to conclude detailed and important findings.

Effect of zinc substitution on magnesium ferrite nanoparticles: Structural, electrical, magnetic, and gas-sensing properties

In this study, we fabricated zinc-substituted magnesium ferrite (MgFe2O4) (ZMF) nanoparticles with the general formula ZnxMg1−xFe2O4 (x = 0.00–0.75) using a surfactant-assisted co-precipitation method and evaluated their H2S gas-sensing performance. Fourier-transform infrared and X-ray diffraction analysis results reveal the formation of a cubic spinel ferrite structure. The effect of zinc substitution on the physico-chemical properties of MgFe2O4 was studied and is discussed herein. The polycrystalline ZMF nanoparticles are magnetic and showed advantageous gas-sensing performance, the results of which reveal that they are sensitive to and selective for hydrogen sulfide (H2S) gas. The ZMF gas sensors exhibited good sensing of various test gases/vapors, such as H2S, H2, Cl2, carbon dioxide, liquid petroleum gas, ammonia, and ethanol while working at room temperature to 400 °C. The Zn0.5Mg0.5Fe2O4 composition produced the highest response toward 10 ppm H2S gas at 400 °C operating temperature.

Structural and Magnetic Properties of NiZn Ferrite Nanoparticles Synthesized by a Thermal Decomposition Method

Ni1−xZnxFe2O4 (x = 0.5, 0.6, 0.7) nanoparticles were synthesized by a thermal decomposition method. The synthesized particles were identified as pure spinel ferrite structures by X-ray diffraction analysis, and they were calculated to be 46–51 nm in diameter by the Scherrer equation, depending on the composition. In the FE-SEM image, the ferrite nanoparticles have spherical shapes with slight agglomeration, and the particle size is about 50 nm, which was consistent with the value obtained by the Scherrer equation. The lattice parameter of the ferrite nanoparticles monotonically increased from 8.34 to 8.358 Å as the Zn concentration increased from 0.5 to 0.7. Initially, the saturation magnetization value slowly decreases from 81.44 to 83.97 emu/g, then quickly decreases to 71.84 emu/g as the zinc content increases from x = 0.5, through 0.6, to 0.7. Ni1−xZnxFe2O4 toroidal samples were prepared by sintering ferrite nanoparticles at 1250 °C and exhibited faceted grain morphologies in the FE-SEM images with their grain sizes being around 5 µm regardless of the Zinc content. The real magnetic permeability (μ′) of the toroidal samples measured at 5 MHz was monotonically increased from 106, through 150, to 217 with increasing the Zinc content from x = 0.5, through 0.6, to 0.7. The cutoff frequency of the ferrite toroidal samples was estimated to be about 20 MHz from the broad maximum point in the plot of imaginary magnetic permeability (μ″) vs. frequencies, which seemed to be associated with domain wall resonance.

Influence of Ca2+ Ion Substitution on Structural, Morphological, Optical, Thermal and Magnetic Behaviour of Mg1-xCaxFe2O4 (0 ≤ x ≤ 0.5) Spinel

The microwave combustion process (MCP) is used to synthesize Mg1-xCaxFe2O4 (0 ≤ x ≤ 0.5) spinel nanoparticles using the fuel l-arginine. Synthesized samples were examined by employing techniques such as XRD, HR-SEM, EDX, DRS-UV, TG-DTA and VSM. The XRD corroborated the constitution of the cubic spinel structure and the average crystallite size was valued to lie in the range of 16.09 to 33.10 nm. The morphology of the Mg1-xCaxFe2O4 (0 ≤ x ≤ 0.5) spinel nanoparticles was observed by HR-SEM. EDX studies confirmed the formation of spinel ferrite structure. Further bandgap values were estimated to be in the range of 1.84 eV to 2.00 eV. TG-DTA studies confirmed weight loss and exothermic transitions. The M-H loops exhibited ferromagnetic behaviour.

X-Ray Diffraction and Magnetic Properties of Nd Substituted NiZnFe2O4 Characterized by Rietveld Refinement

Solid-state method developed neodymium-doped Ni-Zn ferrites exhibit additional orthoferrite and α-Fe2O3 phases. The change in magnetic properties and lattice parameters are influenced by above mentioned extra phases other than the Nickel-Zinc ferrite spinel structure. Observations indicate that curie temperature, as well as saturation magnetization, reduce with an increase in Neodymium concentration. At the same time, for Nd = 0.02, initial permeability has been slightly increased. This paper explains the reason for these changes in terms of diluted octahedral sites replaced with Nd ions instead of Fe-ions and the number of additional phases that are present.

Photocatalytic activity of magnetic core-shell CoFe2O4@ZnO nanoparticles for purification of methylene blue

Magnetic core–shell CoFe2O4@ZnO nanoparticles have been successfully synthesized by using coprecipitation method to provide easy separated nanomaterials and high photocatalytic activity performance. Core–shell nanoparticles with various CoFe2O4-to-ZnO molar ratio (1:2, 1:3, 1:4, 1:5) have been investigated over x-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectroscopy, and vibrating sample magnetometer. XRD spectra confirm the cubic spinel ferrite phase structure of CoFe2O4 and the hexagonal wurtzite phase of ZnO. The crystallite size is found within the range of 14.9–20.6 nm. TEM measurement confirms the good crystallinity of the samples. The magnetic hysteresis shows that CoFe2O4@ZnO has high saturation magnetization of about 30 emu g−1 and coercivity of about 300 Oe. Photocatalytic investigation was carried out using methylene blue (MB) under UV irradiation. Our result yields the enhancement of MB degradation as ZnO content increases. The maximum photodegradation achieved by the core–shell nanoparticles is 57.2%, 60.5%, 65.5%, and 78.3% for molar ratio of 1:2, 1:3, 1:4, and 1:5, respectively. The enhancement of MB degradation can be attributed to the formation of internal structure between CoFe2O4 and ZnO in the form of heterojunction structure. The magnetic properties of core–shell lead to the easy separation between the magnetic core–shell nanoparticles and the final degraded solution by permanent magnet.

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.

Neutron diffraction study and magnetic properties of NiFe2-xScxO4

Polycrystalline NiFe2-xScxO4 (x = 0.00, 0.05 and 0.10) compounds were prepared using solid state reaction method. X-ray diffraction measurements revealed that the compounds exhibited cubic inverse spinel phase without any impurity phases. Room temperature neutron diffraction measurements were carried out to determine magnetic structure along with the structural properties. Raman measurements also supported the cubic inverse spinel ferrite structure of the compounds. The gradual shifts in wave numbers of prominent Raman modes indicated that the Sc3+ ions replaced Fe3+ ions at the B-site. A decrease in saturation magnetization (Ms), Curie temperature (Tc) and anisotropy constant of NiFe2-xScxO4 was observed with an increase of the Sc content.

Structural and magnetic properties of Bi substituted nickel ferrite

Abstract Polycrystalline Ni1-xBixFe2O4 (x = 0.00, 0.05 and 0.10) are prepared by a solid state method. The crystal structure, and magnetic properties are investigated using XRD, Raman and VSM magnetometer. The material formed in the cubic inverse spinel phase without any impurity from XRD. A small distortion of the cubic lattice is observed upon the substitution of Ni by Bi in the A site. The lattice parameter (a) changes non monotonically, first increases then decreases with Bi doping content. From Raman measurements, Raman modes match with the typical modes of cubic inverse spinel ferrite structures belonging to the Fd 3 - m space group. The gradual shifts in wave numbers indicate that the Bi3+ substitutes for Ni3+ at the A-site. The Ms Values of the Ni1-xBixFe2O4 compounds are found to decrease with increasing for 5% doped Bi sample and again increase for 10% Bi doped sample. The Curie temperature TC values of Ni1-xBixFe2O4 are 871, 875 and 885 K, for x = 0.0, 0.05 and 0.1 respectively. It is important to note that the TC value increases in Bi -substituted nickel ferrites compared to pure nickel ferrite.

Structural, electrical, optical and dielectric properties of yttrium substituted cadmium ferrites prepared by Co-Precipitation method

The yttrium substituted cadmium ferrites having composition Cd1-xYxFe2O4 (X = 0.00, 0.125, 0.250, 0.375, 0.500) were synthesized by the co-precipitation method and sintered at 1100 °C for 6 h. Structural, morphological, electrical, optical and dielectric characteristics were explored by XRD, SEM, EDS, FTIR, I–V two probes, UV–Vis and LCR techniques.XRD results confirmed the cubic structure of spinel ferrites. A decrease in lattice constants of the prepared samples was observed with the substitution of Y ions and was attributed to the difference in ionic radii of Y3+ (0.95 Å) and Cd2+ (0.97 Å) ions. Cationic distributions, ionic radii of both tetrahedral and octahedral sites, tolerance factor, oxygen positional parameters, bond lengths, interatomic distances, positional parameters and bond length angles were calculated from XRD data. The morphology of the prepared ferrites was studied using SEM and results ratified the XRD results. EDS confirmed the presence of all inserted elements in Cd1-xYxFe2O4 composition. DC resistivity and drift mobility of soft-ferrites were found to be increased from 1.047 × 108–4.822 × 1010 Ω-cm and 5.87 × 10−12 – 1.045 × 10−14 cm2V−1s−1, respectively, at 523 K with yttrium content confirming the behavior of semiconductor materials. The optical band gap energy calculated from the UV–Vis pattern of the Cd1-xYxFe2O4 system was decreased from 3.6011 to 2.8153 eV. DC resistivity and optical band gaps exposed inverse relation. FTIR results revealed lower and upper-frequency absorption bands in the ranges of 419.31–417.01 cm−1 and 540.95–565.70 cm−1, respectively. Dielectric constant and dielectric losses were in decreasing order, while ac conductivity revealed rising behavior with increasing frequency. Results showed the potential of yttrium doped Cd nanoferrites for applications in high-frequency microwave absorbing devices.

Preparation of exchange coupled CoFe2O4/CoFe2 nanopowders

The CoFe2O4 cobalt ferrite nanoparticles were synthesized by the hydrothermal method. At the reaction temperature of 200 °C, the particle sizes were controlled in the range of 22–41 nm by varying the reaction time tr from 2.0 to 15 h and the spontaneous magnetization Ms of samples was increased from 68.6 to 78.2 Am2/kg. The X-ray diffraction diagrams of obtained samples showed their pure ferrite spinel structure. The highest coercivity Hc value of 184.5 kA/m was achieved by tr = 8 h (denoted by CFO). The sample was synthesized with a time reaction of 2 h which was reduced to form CoFe2 (denoted by CF) nanoparticles by H2 flow 300 mL/min at 380 °C. The CFO/CF powders were milled by the high energy mechanical ball milling in a SPEX 8000. After milling for 2 h, the Ms and Hc values of the CFO/CF nanocomposite powders with 10 wt% CoFe2 nanoparticles fraction were 81.5 Am2/kg and 192.4 kA/m, respectively. The microstructure and magnetic properties of all samples are discussed in detail.

Mesoporous Cobalt Ferrite Nanosystems Obtained by Surfactant-Assisted Hydrothermal Method: Tuning Morpho-structural and Magnetic Properties via pH-Variation.

A facile and cheap surfactant-assisted hydrothermal method was used to prepare mesoporous cobalt ferrite nanosystems with BET surface area up to 151 m2/g. These mesostructures with high BET surface areas and pore sizes are made from assemblies of nanoparticles (NPs) with average sizes between 7.8 and 9.6 nm depending on the initial pH conditions. The pH proved to be the key factor for controlling not only NP size, but also the phase purity and the porosity properties of the mesostructures. At pH values lower than 7, a parasite hematite phase begins to form. The sample obtained at pH = 7.3 has magnetization at saturation Ms = 38 emu/g at 300 K (54.3 emu/g at 10 K) and BET surface area SBET = 151 m2/g, whereas the one obtained at pH = 8.3 has Ms = 68 emu/g at 300 K (83.6 emu/g at 10 K) and SBET = 101 m2/g. The magnetic coercive field values at 10 K are high at up to 12,780 Oe, with a maximum coercive field reached for the sample obtained at pH = 8.3. Decreased magnetic performances are obtained at pH values higher than 9. The iron occupancies of the tetrahedral and octahedral sites belonging to the cobalt ferrite spinel structure were extracted through decomposition of the Mössbauer patterns in spectral components. The magnetic anisotropy constants of the investigated NPs were estimated from the temperature dependence of the hyperfine magnetic field. Taking into consideration the high values of BET surface area and the magnetic anisotropy constants as well as the significant magnetizations for saturation at ambient temperature, and the fact that all parameters can be adjusted through the initial pH conditions, these materials are very promising as recyclable anti-polluting agents, magnetically separable catalysts, and targeted drug delivery vehicles.

Magnetic transformation of Zn-substituted Mg-Co ferrite nanoparticles: Hard magnetism → soft magnetism

Zinc substituted magnesium-cobalt ferrite nanoparticles having the basic composition Mg0.2Co0.8−xZnxFe2O4 (x = 0.0, 0.2, 0.4, 0.6 and 0.8) were successfully synthesized using sol–gel auto combustion method. The results show that the doping amount of Zn2+ ions has a great influence on its structure and magnetic properties. X-ray diffraction (XRD) measurements show that Mg0.2Co0.8−xZnxFe2O4 has a good phase formation, and all samples have single-phase cubic spinel structure. The average crystallite size is calculated from Scheller's formula to be between 49 and 54 nm. And the lattice constant increases from 8.38 to 8.43 Å with the increase of Zn2+ ions content. Fourier transform infrared (FTIR) measurements also confirm the formation of the cubic spinel structure of ferrite. The ferrite samples were observed by scanning electron microscopy (SEM) to be spherical nanoparticles. The magnetic properties of the samples have been determined at room temperature by vibrating sample magnetometer (VSM). The results show that the magnetic properties of Mg-Co ferrite are significantly affected by the doping amount of Zn2+ ions. For Zn-substituted Mg-Co ferrites, the magnetic properties decrease obviously with the increase of Zn content. This rapid decrease of magnetic properties reveals that the magnetic properties of Zn-substituted magnesium-cobalt ferrite have realized the transition from hard magnetic to soft magnetic. Meanwhile, the coercivity is Hc = 21.26 Oe, the saturation magnetization is 4.56 emu/g and the remanent magnetization is 0.03 emu/g for Mg0.2Zn0.8Fe2O4 sample. This also indicates that the ferrite samples prepared have a transition from ferromagnetic behavior to superparamagnetic behavior. The smaller coercivity value confirms that soft ferrite has been obtained. Meanwhile, this transition from hard magnetism to soft magnetism can be used as a potential high frequency soft magnetic material.

Impact of Defects on Magnetic Properties of Spinel Zinc Ferrite Thin Films

The recent developments in the study of magnetic properties in the spinel zinc ferrite system are explored. Engineering of ionic valence and site distribution allows tailoring of magnetic interactions. Recent literature is reviewed, and own investigations are presented for a conclusive understanding of the mechanisms responsible for the magnetic behavior in this material system. By varying the Zn‐to‐Fe ratio, the deposition, as well as thermal annealing conditions, ZnFe2O4 thin films with a wide range of crystalline quality are produced. In particular, the focus is on the magnetic structure in relation to spectroscopic properties of disordered ZnFe2O4 thin films. Comparing the cation distribution in film bulk (optical transitions in the dielectric function) and near‐surface region (X‐ray absorption), it is found that an inhomogeneous cation distribution leads to a weaker magnetic response in films of inverse configuration, whereas defects in the normal spinel are likely to be found at the film surface. The results show that it is possible to engineer the defect distribution in the magnetic spinel ferrite film structure and tailor their magnetic properties on demand. It is demonstrated that these properties can be read out optically, which allows controlled growth of the material and applications in future magneto‐optical devices.

Magnetic, Structural, and Optical Properties of Gadolinium-Substituted Co0.5Ni0.5Fe2O4 Spinel Ferrite Nanostructures

Gadolinium-substituted cobalt–nickel ferrite Co0.5Ni0.5GdxFe2-xO4 (0 ≤ x ≤ 1.0) nanostructures have been synthesized by hydrothermal approach which results more hydrophilic surface properties important for biomedical applications. Structural analysis by X-ray diffraction revealed the formation of a single-phase spinel ferrite for all samples and crystallite size is ranging from 13 to 28 nm. Lattice constant decreases with increasing Gd3+ ion concentration due to differences between ionic radii of Gd3+ and Fe3+. Morphological analysis by scanning and transmission electron microscopy indicated the shape transformed from agglomerated particles into rod-shaped with increasing Gd content. Fourier transform infrared analysis also correlated the presence of the spinel ferrite structure. Optical band gap measurement implied that band gap decreases with increasing Gd content. In order to determine magnetic properties of cobalt–nickel spinel ferrite nanostructures, isothermal magnetization measurements have been obtained at 300 and 15 K using vibrating sample magnetometer. Magnetic properties are strongly depending on Gd substitution ratio, which alters the crystallite size, cation distribution, and exchange interactions between octahedral and tetrahedral sites of nanostructures. Saturation magnetizations decreased with increasing Gd substitution at both temperatures since cation distribution at different sites and large lattice distortion caused by Gd3+ ion substitution. Due to complex relations between the shape anisotropy, crystallite size, grain boundaries, secondary phases, and increasing Gd content observed in Co0.5Ni0.5GdxFe2-xO4 nanostructures, coercivity results in different magnetocrystalline anisotropy behavior.

Effects of structure and electronic properties of spinel ferrites on their emissivity in middle and short wavebands

In this study, the samples of a series of spinel ferrites (Fe3O4, NiFe2O4, and CuFe2O4) were prepared to investigate their emissivity performance in the middle and short wavebands. The emissivity of the samples was measured in the temperature range of 27–500 ​°C. The results show that Fe3O4 had the highest average emissivity values of 0.98 in 8–14 ​μm waveband and 0.97 in 3–5 ​μm waveband. In addition, CuFe2O4 had the second-highest values of 0.95 in 8–14 ​μm waveband and 0.92 in 3–5 ​μm waveband. Finally, NiFe2O4 had the lowest values of 0.94 in 8–14 ​μm waveband and 0.59 in 3–5 ​μm waveband. Given that the force constant KO has an effect on the lattice distortion, which, in turn, is an important factor influencing the emissivity performance in 8–14 ​μm waveband, infrared spectrum measurements and an X-ray diffraction refinement of the spinel ferrites were performed for the calculation of KO. The results show that Fe3O4 had a smaller KO value (94.64×103) than NiFe2O4 (95.37×103) and CuFe2O4 (94.72×103), which confirms that KO has an inverse relationship with the emissivity in 8–14 ​μm waveband for the studied series of spinel ferrites. Furthermore, the first principle calculations were used to discuss the effect of electronic transition on the emissivity in 3–5 ​μm waveband. The calculation results show that, for Fe3O4, the O 2p orbitals pass through the Fermi level, resulting in the electronic transition near the Fermi level needs less energy to overcome the band gap than that for NiFe2O4 and CuFe2O4, which indicates that the electronic transition for Fe3O4 is easier. This implies that Fe3O4 would have higher emissivity in 3–5 ​μm waveband than NiFe2O4 and CuFe2O4 do. The band gap values of the series of spinel ferrite samples were measured by UV–Vis diffuse reflectance spectroscopy, and the variation trend of the band gap values is opposite to that of the 3–5 ​μm band emissivity. This study implies that the development of high-infrared-radiation materials with a ferrite spinel structure should aim at reducing the force constant KO and band gap, which is a possible direction for future research.

Magnetic transformation of Zn‑substituted Ni–Co ferrite nanoparticles

A series of ferrite samples with the compositional formula, Ni0.2ZnxCo0.8−xFe2O4 (x = 0.0, 0.2, 0.4, 0.6 and 0.8), was prepared using the citrate-based sol–gel method for the better understanding of zinc doping on the structural and magnetic properties. X-ray diffraction (XRD) studies of the samples showed single-phase ferrite cubic structure without any secondary phases, with the average crystallite size D = 103–130 nm for the samples heat-treated at 950 °C. TEM micrograph shows nearly sphere-shaped particles with particle size consistent with the XRD results. The lattice parameter increased linearly with increasing Zn2+ ion content. Fourier transform infrared (FT-IR) measurements also confirm the formation of the cubic spinel structure of ferrite. The ferrite samples were observed by scanning electron microscopy (SEM) to be spherical nanoparticles. The surface morphology and stoichiometric ratio of the compositional elements were analyzed by scanning electron microscopy equipped with energy-dispersive spectroscopy (EDS). EDS showed that the elemental ratios were stoichiometric. The static magnetism of the magnetometer was studied by using a vibrating sample magnetometer (VSM). An examination of the magnetic properties revealed an increase in saturation magnetization with increasing Zn concentration up to x = 0.2 and a decrease thereafter. These results could be explained using Neel’s collinear two-sub-lattice model and three-sub-lattice non-collinear model suggested by Yafet and Kittel. The magnetic cubic anisotropy constant determined by the law of approach to saturation decreased with increasing Zn content. For Zn-substituted Ni–Co ferrites, the magnetic properties decrease obviously with the increase in Zn2+ ion content. This rapid decrease in magnetic properties reveals that the magnetic properties of Zn-substituted nickel–cobalt ferrite have realized the transition from hard magnetism to soft magnetism. The smaller coercivity value confirms that soft ferrite has been obtained. Meanwhile, this transition from hard magnetism to soft magnetism can be used as a potential high-frequency soft magnetic material.

Effects of Ni2+-Substitution on Structural, Magnetic and Electrical Properties of Cadmium Spinel Ferrite Nanoparticles via Chemical Route

Ni2+ substituted spinel ferrites with formula CdxNi1-xFe2O4 were prepared by microwave Sol-gel method. The XRD analysis of the synthesized ferrite confirms the formation of cubic spinel structure of ferrite. Rietveld refined XRD patterns revealed the cubic spinel phase with Fd-3m space group. The oxygen position and the cation distribution are determined by means of Rietveld analysis, indicating the existence of mixed ferrites in each sample. The magnetic properties of all ferrites were studied by using a vibration sample magnetometer. The fast synthesis of spinel ferrites is yielded due to use of the microwave sintering technique.

Effect of matrix type on the mechanical and magnetic properties of ferrite based natural and nitrile rubber nanocomposites

Copper doped nickel ferrite particles were prepared using co-precipitation method. The prepared particles were analysed using FTIR, XRD and SEM to confirm the formation of spinel ferrite structures, particle size and distribution. These ferrite nanoparticles are then embedded in natural and nitrile rubber at different loadings to compare the effect of matrix type on the mechanical and magnetic properties of composite samples. Nitrile rubber (NBR) composites show excellent magnetic properties than natural rubber (NR) composites. Saturation magnetisation, magnetic coercivity and magnetic retentivity values of NBR composites are superior to NR composites. In contrast mechanical properties are found to be inferior for NBR composites.

Role of doped nitrogen and sulphur in cobalt/cobalt-zirconium nanoferrites synthesized by facile methods

Nitrogen/sulphur doped cobalt and cobalt zirconium mixed nanoparticles were synthesised by coprecipitation/wet impregnation methods. X-ray diffraction and X-ray fluorescence spectroscopic studies reveal the formation of monophasic cubic spinel structure with expected stoichiometries. Average crystallite sizes vary in the range of 17–26 nm. X-ray photoelectron and energy dispersive X-ray spectroscopic studies indicate the successful incorporation of non-metal elements into the ferrite lattice. Fourier-Transform infrared and Raman spectroscopic studies confirm the presence of stable cubic spinel ferrite structure of cobalt ferrite after doping. Evidences point towards the insertion of sulphur and nitrogen as cations, contrary to other metal oxides like titania. Thermal stability studies prove that ferrite formation is a continuous process producing stable crystalline spinel nanoparticles around 700 °C. Magnetic measurements at room temperature indicate decrease in saturation magnetisation with doping whereas coercivity increases with reduction in the particle size. DC resistivity measurements in the range of 30–400 °C show decrease in resistivity with increase in temperature, indicating semiconducting behaviour. The results of microstructural, magnetic and dielectric properties suggest that the prepared nanoparticles are suitable for catalysis, adsorption recycle, high frequency devices, inductors and biomedical applications.