Fe2O4 Ferrites Research Articles

Correlation between the composition, structural parameters and magnetic properties of spinel-based functional nanocomposites

The “soft/soft” (CoFe 2O4)x/Ni0.4Cu0.2Zn0.4Fe2O4)y nanocomposites (NCs), as a function of the phase ratio, have been synthesized via the green sol–gel method using 6 dates. The correlation between chemical composition, structural parameters and magnetic properties was investigated. The average crystallite size (Dmax) of the products was found to be within the range of 24.6-41.1 nm. It was observed that an increase in the CoFe 2O4 content leads to an increase in the most probable size of the coarse fraction and a decrease in the most probable grain size of the fine fraction. As the (Ni0.4Cu0.2Zn0.4)Fe2O4 content increases, the average size of the fine and coarse fractions decreases. The magnetic properties were investigated in a wide magnetic field range (80 kOe) at 300 and 10 K. The maximum magnetization saturation or Ms (∼124.3 emu/g at 10 K and ∼81.2 emu/g at 300 K) was observed for the sample with the ratio 1/2 that was ∼30% higher than Ms for the pure (Ni0.4Cu0.2Zn0.4)Fe2O4 ferrite at 10 K (∼86.9 emu/g) and ∼35% higher than at 300 K (∼52.8 emu/g). This fact clearly demonstrates the presence of a synergetic effect in the NCs. The dominance of low-temperature Ms values was explained by the lack of thermal energy of the disordered spin. The presence of a synergetic effect in the (CoFe 2O4)x/Ni0.4Cu0.2Zn0.4Fe2O4)y NCs can be observed due to a strong coupling between the two magnetic phases, according to careful analysis of the correlation between the chemical composition, structural parameters and magnetic properties.

Effect of sintering temperature on structural, morphological, magnetic, and electrochemical properties of Mn0.3Co0.2Zn0.5Fe2O4 Ferrite

Effect of sintering temperature on structural, morphological, magnetic, and electrochemical properties of Mn0.3Co0.2Zn0.5Fe2O4 Ferrite

Effect of Sintering condition on Magnetization and Microstructure of CuxCo(1-x)Fe2O4 Ferrites

Effect of Sintering condition on Magnetization and Microstructure of CuxCo(1-x)Fe2O4 Ferrites

Effect of rare earth doping on magnetic and dielectric properties of NiZnMn ferrites

In present work, RE0.01Ni0.3Zn0.4Mn0.3Fe2O4 (RE=Fe, La, Nd, Sm, Gd, Dy, Yb) ferrites with strictly controlled main composition were prepared. X-ray diffraction analysis shows that the lattice constant decreases with the increase of atomic number of rare earth. The infrared spectra demonstrate the changes of tetrahedral and octahedral bonds. The saturation magnetization is about 74 emu/g and initial permeability is about 120 for undoped ferrite. They decrease slightly after rare earth doping, but the impact of different rare earth on Ms is same. The Curie temperature of almost all samples is 262 ℃. Zero field cooling-field cooling curves demonstrate the existence of spin glass state or superparamagnetism at high temperature. Sm, Gd and Dy doped ferrites have special dielectric properties with more relaxation processes. Appropriate rare earth doping greatly improve the cut-off frequency, dielectric constant for MHz device materials and dielectric loss for GHz electromagnetic wave absorption materials.

The effect of sintering conditions on thermal stability and magnetic properties of Ni0.4Zn0.2Mn0.4Fe2O4 ferrites

The effect of sintering conditions on thermal stability and magnetic properties of Ni0.4Zn0.2Mn0.4Fe2O4 ferrites

Effects of sintering temperature on structural, magnetic and microwave absorption properties of Ni0.5Zn0.5Fe2O4 ferrites

Ni0.5Zn0.5Fe2O4 ferrites were prepared by the sol–gel auto-combustion method and sintered at 1150 °C, 1250 °C, 1350 °C and 1450 °C. Structural, magnetic, and microwave absorption properties were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectra, Vibrating sample magnetometer and vector network analyzer, respectively. Sintering temperature has a remarkable effect on the concentration of both Fe2+ and oxygen vacancies and further influence the permittivity and permeability. The excellent microwave absorption properties are obtained at the sintering temperature of 1350 °C, and its effective absorption bandwidth reaches 9.55 GHz from 3.67 to 13.22 GHz at a thin thickness of 2.5 mm. It is notable that the two reflection loss peaks of Ni0.5Zn0.5Fe2O4 ferrites appeared at both low and high frequency regions. The peak at low frequency is associated with the great magnetic loss tangent (greater than1) and the peak at high frequency satisfies the quarter-wavelength matching model. The microwave absorption performance of Ni0.5Zn0.5Fe2O4 ferrites was attributed to both dielectric and magnetic mechanisms while the magnetic part dominates.

Impact of Mn2+-Si4+ co-substitution on the electronic structure of Zn0.3Mn0.7Fe2O4 ferrites studied by X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) has been employed to explore the electronic structure of Zn0.3Mn0.7+xSixFe2-2xO4 (x = 0.0–0.3) ferrite series. The Si2p XPS spectra insinuated the presence of Si ions in the +4 valence state. The elemental Si0 and suboxide SiOx are present in the system, the former showing an increase and the latter a decrease in atomic percentage upon Mn–Si substitution. It is also inferred that a fraction of Si0 might be residing at the grain boundaries; however, more studies are required to substantiate this. The Fe2p XPS spectra stipulate that ferrous and ferric ions co-occur in the system. The ferrous ions occupy the octahedral sites while the ferric ions dwell on both the octahedral and the tetrahedral sites. The O1s spectra indicate a remarkable increase in the oxygen defects with increasing Mn–Si substitution (x). The Mn2p XPS data indicate that the Mn+2 states show an overall increasing tendency with increasing Mn–Si concentration. Also, the Mn+4/Mn+3 ratio shows an increment with an increase in Mn–Si substitution.

Magnetodielectric and low-frequency microwave absorption properties of entropy stabilised ferrites and 3D printed composites

High-entropy ferrites (HEFs) are a new group of high-entropy oxides with unique magnetodielectric properties that offer a wide array of possibilities for high-frequency applications. Various ions were introduced at octahedral sites in the spinel structure to test the role of the high-entropy structure's formation on its properties. The structural analysis confirmed the formation of single-phase spinel structure even for (FeCoNiMg)(FeCr)2O4 HEF. Dielectric studies showed that introducing Mg2+ and Cr3+ ions increased electrical conductivity and dielectric losses over a wide frequency range. Low frequency (from 0.8 to 1.5 GHz) studies showed that for (FeCo)Fe2O4 and (FeCoNi)Fe2O4 ferrites reflection losses (RL) are negligible, while for both (FeCoNiMg)Fe2O4 and (FeCoNiMg)(FeCr)2O4 ferrites RL higher than 90% were observed. The temperature dependence on the absorption properties was confirmed for (FeCoNiMg)(FeCr)2O4 HEF. The highest absorption window was observed for 343 K, for which RL higher than 90% appears from 1.25 to 1.5 GHz. The possibility of the 3D printing of microwave absorption composites from HEFs was also tested. It was confirmed that the addition of (FeCoNiMg)(FeCr)2O4 HEF drastically increases the absorption properties up to 85.5% at 2.72 GHz for the absorber with the same thickness as made from the pure acrylonitrile butadiene styrene (ABS). Interestingly, the EMI shielding properties of these composites are mainly related to the dielectric losses improved by the addition of entropy stabilised ferrites in 3D printed composites with various ferrite concentrations.

Investigations on the magnetocaloric effect and critical behavior of CoGa1.2Fe0.8O4 spinel ferrite

The critical behavior of (NixZn1-x)Fe2O4 ferrites doped with Mg, Cu and Gd at Ni and Zn sites has been widely reported before. Among them, the types of magnetic interaction in these ferrites are observed between the 3D-Heisenberg and mean-field models, satisfying the triple critical mean-field model and the 3D-Heisenberg model, and beyond any theoretical models in some cases. In this work, the critical behavior of CoGa1.2Fe0.8O4 with Ga-doped at the Fe-sites has been studied. The main results are as follows: the sample has a second-order magnetic phase transition at a temperature of Tc ​= ​210 ​K. The Rhodes-Wolfarth ratio RWR ≈1 means that the magnetization is due to the contribution of local magnetic moments. The critical parameters obtained by the modified Arrott method (and the Kouvel-Fisher one) were β ​= ​0.498 (0.509), γ ​= ​1.005 (0.924) and δ ​= ​3.018 (2.815). The critical exponents together with the exchange distance J(r) ∝ r−4.5082 confirm that the magnetic interaction in CoGa1.2Fe0.8O4 belongs to the mean-field model (β ​= ​0.5, γ ​= ​1 and δ ​= ​3), indicating that CoGa1.2Fe0.8O4 has a long-range ferromagnetic interaction, which is different from the magnetic interaction in the (NixZn1－x)Fe2O4 ferrites doped at Ni and Zn sites.

Magnetic and microwave absorption properties of Ni0.6Zn0.4Fe2O4 /SrFe12O19 composites

In this work, pure Ni0.6Zn0.4Fe2O4 (NZFO) and Ni0.6Zn0.4Fe2O4/SrFe12O19 (NZFO/SFO) composites have been prepared by solid-state reaction method, their microwave absorbing and magnetic properties have been systematically investigated. The samples were characterized by XRD, FTIR, SEM, SQUID and VNA. The results show that the maximum reflection loss and bandwidth (RL < −10dB) of Ni0.6Zn0.4Fe2O4 ferrite are −36.25 dB and 5.5 GHz, but the bandwidth below −10dB is divided into two parts. In order to obtain a continuous bandwidth below −10dB for Ni0.6Zn0.4Fe2O4 ferrite, strontium ferrite is added to adjust the microwave absorption performance. When the mass ratio of Ni0.6Zn0.4Fe2O4 ferrite and SrFe12O19 ferrite is 1:2 and the thickness is only 1.8 mm, NZFO/SFO composite exhibits excellent microwave absorbing properties. The maximum reflection loss is −25.9 dB, and the absorption bandwidth for RL < −10dB was 6.4 GHz in the frequency range from 11.6 GHz to 18 GHz, covering the entire x-band. The results show that the improvement of the microwave absorption performance of NZFO/SFO composites is related to the parameters such as interface polarization, dipole polarization, natural resonance, eddy current loss, conduction loss and impedance matching. The ideal experimental results show that the NZFO/SFO absorbent has the characteristics of strong absorption, wide bandwidth, and thin layer, and has broad application prospects in civilian and military fields.

Tuning the structural, optical and magnetic properties of NiCuZn (Ni0.4Cu0.3Zn0.3Fe2O4) spinel ferrites by Nb2O5 additive

Ni0.4Cu0.3Zn0.3Fe2O4 ferrites with various compositions (0–5 wt. %) of Nb2O5 additive were synthesized by the sol-gel method with an aim to investigate their physical properties. The analysis of Rietveld refined X-ray diffractograms confirms formation of ferrites with a single-phase spinel structure having space group Fd3m. The result indicates that there is an enhancement in the lattice parameter values with increasing Nb2O5 content. The nanoparticles in the shapes of spheres and cubes with few agglomerations were evident from field emission scanning electron microscope images of ferrites. The elemental analysis from energy dispersive X-ray spectrum confirms the stoichiometric occurrence of constituent elements within the prepared samples. The Raman spectra confirm the cubic spinel structure of the prepared ferrite samples. The Fourier transform infra-red spectra confirm the superseding of Nb5+ ions in the unit cell of NiCuZn ferrite. Oxidation states of the elements within the ferrite were confirmed by means of X-ray photoelectron spectroscopy. The UV–Visible diffused reflectance spectroscopy results show that the band gap energy values were reduced with the increasing wt.% of Nb2O5 additive in the ferrite. The Nb2O5 additive reduces the saturation magnetization and coercivity of all the ferrite samples. The study reveals that the controlled amount of Nb2O5 additive in NiCuZn ferrite can tune the soft magnetic behavior and optical parameters of the ferrite at room temperature.

Spinel M0.5Zn0.5Fe2O4 (M = Ni, Co, and Cu) ferrites for energy storage applications: Dielectric, magnetic and electrochemical properties

Spinel structured M0.5Zn0.5Fe2O4 (M = Ni, Co, Cu) were synthesized through a solid state route. Phase analysis of the samples showed the formation of a single phase spinel structure. Fourier transform infrared spectroscopy also confirm the presence of tetrahedral and octahedral sites belonging to spinel structure. The microstructural analysis of the samples revealed a grain size ranging from 0.5 to 3.7 μm. The photoluminescence spectroscopy indicated the generation of oxygen vacancies and structural defects in the lattice of the samples. The obtained dielectric constant and loss values (at 1 MHz) varied between 11 and 35, and 0.006 to 1.2, respectively. The variation in dielectric properties was dependent on polarization species, crystallite size, defects and oxidation states. The samples showed a ferromagnetic behavior at room temperature. The electrochemical performance of Cu0.5Zn0.5Fe2O4 showed the most favorable results such as the lowest overpotential of 490 mV, the highest specific capacitance of 462 F/g, and the lowest charge-transfer resistance of 876 Ω, suggesting its potential for energy storage applications.

Investigation of the structural, optical, electrical and dielectric proprieties of LiCd0.5Fe2O4 spinel ferrite

The spinel ferrite material families are subjected to diverse studies according to their wide field application. In this work, the LiCd0.5Fe2O4 ferrite was successfully synthesized by a conventional solid-state method. The structural, optical, electrical and dielectric characterizations were treated. The Rietveld refinement method explored cubic spinel structure (Fd3‾m space group) with a lattice parameter: a = 8.628 Å, α = 90°. Besides, the surface micrograph shows a strong agglomeration of the grains. Optical results were calculated using diffuse reflectance data and Kubelka Munk theory. They show the semiconductor nature with a band gap around 2.9 eV and Urbach energy around 0.14 eV.The electrical measurements were studied over a range of frequency (40 Hz–1 MHz) and through large temperature scale (200 K–380 K) using the complex impedance spectroscopy technique. The AC conductivity behavior was described by the jump relaxation model, which obeys to the Jonscher's law. The complex impedance analysis has suggested the presence of the contribution of the grains, the grain boundaries and interface in the conduction mechanism. A reduction in real part Z′ was observed as a function of temperature and frequency, which indicates an increase in ac conductivity and a negative temperature coefficient of resistance. Hence, the complex modulus plots have affirmed the presence of grain boundaries contribution in the material. Both the complex modulus and impedance investigations have confirmed that the synthesized material exhibits a non-Debye type of relaxation. Finally, the dielectric behavior of the studied sample shows a polarization effect and the permittivity graphs are fitted theoretically with the Cole-Cole model.

The recycle of spent Zn–C batteries and the synthesis of magnetic nanocomposite from graphene nanosheets and ferrite and its application for environmental remediation

In this research work, the well-known manganese zinc ferrite Mn0.8Zn0.2Fe2O4 (MZF) magnetic material ferrite was prepared using an eco-friendly method from spent Zn–C batteries (SZCBs) and doped with the high surface area graphene oxide (GO) nanosheets to form MZF/GO magnetic nanocomposite. The prepared MZF/GO magnetic nanocomposite was characterized using DTA-TG, XRD, FT-IR, TEM, and VSM techniques for examining the morphological structure, functional groups, and magnetic properties of the prepared nanocomposite. The characterization results indicated the formation of the Mn0.8Zn0.2Fe2O4 ferrite, and GO, and the homogenous distribution of the ferrite on the GO nanosheets. MZF/GO magnetic nanocomposite was then used as a solid adsorbent for removing Acid Red (AR) dye from water. The results presented the suitability of the pseudo-second-order kinetic model, exothermic, electrostatic, and the physical nature adsorption process, with a removal capacity of 49.9 mg AR dye per g MZF/GO magnetic nanocomposite. The thermodynamics of the adsorption process showed the spontaneity of the process, with a negative entropy change value of −63.7 J/mol.K, negative enthalpy change value of −34.5 kJ/mol, and negative Gibbs free energy change value of −17.5 kJ/mol, indicating that the adsorption of the AR dye by MZF/GO magnetic nanocomposite is enthalpy-driven-process. Moreover, MZF/GO magnetic nanocomposite could be used for the remediation of real environmental water polluted with AR dye, and also could be used for five consecutive cycles with high efficacy for times for the adsorption/removal of AR dye.

Cadmium Substitution Effect on Microstructure and Magnetic Properties of Mg-Cu-Zn Ferrites

The microstructure, optical, and magnetic properties of CdxMg0.3-xCu0.2Zn0.5Fe2O4 ferrites prepared by the citrate auto-combustion method were investigated. The samples were analyzed by X-ray diffraction, scanning electron microscopy, UV-Vis spectroscopy, https://soh.iums.ac.ir/uploads/uv-vis_-_2.pptx X-ray energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, and vibrating sample magnetometer. Rietveld refinement of XRD patterns shows a single-phase cubic structure (space group Fd3¯m) for the samples with x up to 0.20, while the impurity phase of CdO is observed in the samples with x = 0.25, 0.30. As the substitution content increases, the presence of non-magnetic Cd2+ ions in the octahedral site and the migration of Fe3+ions from the octahedral site to the tetrahedral site decreases the saturation magnetization of the samples. Comparison of the bandgap energy of the samples shows an increasing trend with Cd substitution for x up to 0.20 and then decreases, which can be interpreted in terms of changes in the electronic structure of the samples. Improvement in dielectric properties of the samples with increase of Cd2+ content for x up to 0.20 may be attributed to easier transfer and electron exchange between Fe3+and M2+ ions.

Synthesis and investigation on the microstructural and electrical proprieties of Ni0.1Co0.5Cu0.4Fe2O4 ferrite prepared using sol-gel route

In this work, the new polycrystalline spinel-type Ni0.1Co0.5Cu0.4Fe2O4 (NCCF) ferrite has been prepared via sol-gel method and analyzed using X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively for structural, morphological, and elemental analysis. The refinement of X-ray pattern via the Rietveld technique asserts that the prepared sample exhibits the formation of a mono-phase cubic spinel structure with a Fd3¯m space group. The modified Scherrer and Williamson Hall (W–H) equations were used to evaluate the average crystallite size in the NCCF. Dielectric and complex impedance properties have been investigated in frequency range 102 ≤ f ​≤ ​106 ​Hz and in temperature range 300 ​≤ ​T ​≤ ​400 ​K using spectroscopy impedance. The ac conductivity was modeled using Jonscher's power law from 300 ​K to 340 ​K and Jonscher's augmented equation from 350 ​K to 400 ​K. Moreover, the temperature dependence of the dc conductivity revealed a semiconductor-metal transition occurring in our sample at TSM ​= ​370 ​K. The dielectric constant was exhaustively investigated vs. frequency and temperature and was obtained according to Maxwell-Wagner polarization. Col-Col plot of impedance data was used to evaluate the grain and grain boundary contributions in the NCCF sample.

Effect of Zr/Co Co-substitution on structural, electrical and magnetic properties of Ni0.75Zn0.25Fe2O4 ferrites by sol–gel auto-combustion method

Effect of Zr/Co Co-substitution on structural, electrical and magnetic properties of Ni0.75Zn0.25Fe2O4 ferrites by sol–gel auto-combustion method

Effects of Sintering Temperature on Structural, Magnetic and Microwave Absorption Properties of Ni0.5zn0.5fe2o4 Ferrites

Effects of Sintering Temperature on Structural, Magnetic and Microwave Absorption Properties of Ni0.5zn0.5fe2o4 Ferrites

Mn doped Ni-Zn ferrite thick film as a highly selective and sensitive gas sensor for Cl2 gas with quick response and recovery time

The Ni0.7-xMnxZn0.3Fe2O4 (x = 0.1–0.4) ferrites were characterized by X-ray diffraction, Transmission electron microscopy, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy. The thick films of these ferrites were fabricated on a glass substrate to use as a Cl2 sensor. The ferrite thick film with composition x = 0.3 showed a selectively high response towards Cl2 gas at an operating temperature of 100 °C. The response varied from 115 to 212% for 20–300 ppm of Cl2 gas. The response time was found to be within 10 s while the recovery time was less than 15 s. The results were quite reproducible thus making this material a good sensor for Cl2 gas.

Sol-gel synthesis of mixed ferrites for biomedical applications

The effect of mixed ferrites nature and that of several coatings on the magnetic properties and thus, on the heating ability of nanoparticles, was studied. The Mg0.4Ca0.6Fe2O4 and Mn0.5Ga0.5Fe2O4 ferrites, synthesized by sol-gel method, followed by heat treatment, were coated with oleic acid + Pluronic® F-127, carboxymethyl-dextran sodium or polyvinylpyrrolidone. An average particle size of 12 and 15 nm was obtained for the Mg-Ca and Mn-Ga ferrites, respectively. Samples, before and after coating, revealed a heating capacity over 42°C and a superparamagnetic behaviour. The compounds accomplished the requirements of heating ability and specific absorption rate for magnetic hyperthermia treatment. The Mn0.5Ga0.5Fe2O4 system was more efficient than the Mg0.4Ca0.6Fe2O4 system. Copyright © 2018 VBRI Press.