Spinel Ferrites Research Articles

Ultrasonic chemical synthesis of zinc-manganese ferrites with improved magnetic properties

Zinc-Manganese spinel ferrites (Zn1-xMnxFe2O4) are nowadays very attractive magnetic materials for cancer diagnostic and therapy. With the help of intense ultrasonic waves, sonochemical synthesis method was used to prepare stoichiometric and chemically homogenous nanoparticles by varying the manganese content. The crystal structure along with the size and shape of the as-prepared nanoparticles were described using XRD, TEM and FT-IR techniques, while cations distribution was carefully investigated using XPS and Mössbauer spectroscopic techniques and supported with density functional theory calculations. The crystal structure study revealed the presence of a pure single cubic spinel phase, where the unit-cell and the size were observed to decrease as the manganese incorporation was increased with clear indication of cationic redistribution and degree of inversion variations. Due to the very small variation of the total energy between different configurations, the probability of formation of a mixed phase was found to be very high in such a way that the more mixed was the phase, the more stable it was. A relevant fact was the noticed quasi-systematic ionic exchange made possible by the very short reaction times and high energy offered by the ultrasonic waves. For manganese concentrations up to 60%, the systematic ionic process started by incorporating manganese ions into octahedral sites and pushing iron ions to migrate and replace those of zinc in tetrahedral sites. Such an ionic movement was of central importance for the improvement of the magnetic properties due to the establishment of super-exchange interactions. Such an ionic engineering should definitely open the way to promising applications in biomedical imaging.

Electrospun Mesoporous Ni0.5Zn0.5Fe2O4 - CNT - Hollow Carbon Ternary Composite Nanofibers as High Performance Electrodes for Advanced Symmetric Supercapacitors.

Spinel ferrites have attracted considerable interest in energy storage systems due to their unique magnetic, electrical and catalytic properties. However, they suffer from poor electronic conductivity and low specific capacity. We have addressed this limitation by synthesizing composite hollow carbon nanofibers (HCNF) embedded with nanostructured Nickel Zinc Ferrite (NZF) and Multiwalled carbon nanotubes (CNT), through coaxial electrospinning. These ternary composite nanofibers NZF-CNT-HCNF have a high specific capacity of 833 C g-1 at a current density of 1 A g-1 and have a capacity retention of 90 % after 3000 cycles. Their performance is much better than pure NZF fibers (180 C g-1) or hollow carbon nanofibers (96 C g-1), suggesting synergy between various constituents of the composite. A symmetric supercapacitor fabricated from NZF-CNT-HCNF composite nanofibers (30 % NZF) has a high specific capacity of 302 C g-1 (302 A g-1) at a current density of 1 A g-1 and has a capacity retention of 95 % after 5000 cycles. At the same current density, the device has a high energy density of 39 Whkg-1 and power density of 1000 Wkg-1 at a current density of 1 A g-1. This performance can be attributed to the high specific surface area (776 m2 g-1), mesoporosity (pore size ~4 nm), interconnectedness of the nanofibers and high electrical conductivity of CNTs. These fibers can be used as light-weight high performance electrode materials in advanced energy storage devices.

Impact of rare earth Ce3+ on the structural, and magneto-dielectric response of chemically derived Mg0.5Zn0.25Co0.25CeyFe2-yO4 spinel ferrites

Impact of rare earth Ce3+ on the structural, and magneto-dielectric response of chemically derived Mg0.5Zn0.25Co0.25CeyFe2-yO4 spinel ferrites

Enhancement of Magnetic Shielding Based on Low-Noise Materials, Magnetization Control, and Active Compensation: A Review

Magnetic-shielding technologies play a crucial role in the field of ultra-sensitive physical measurement, medical imaging, quantum sensing, etc. With the increasing demand for the accuracy of magnetic measurement, the performance requirements of magnetic-shielding devices are also higher, such as the extremely weak magnetic field, gradient, and low-frequency noise. However, the conventional method to improve the shielding performance by adding layers of materials is restricted by complex construction and inherent materials noise. This paper provides a comprehensive review about the enhancement of magnetic shielding in three aspects, including low-noise materials, magnetization control, and active compensation. The generation theorem and theoretical calculation of materials magnetic noise is summarized first, focusing on the development of spinel ferrites, amorphous, and nanocrystalline. Next, the principles and applications of two magnetization control methods, degaussing and magnetic shaking, are introduced. In the review of the active magnetic compensation system, the forward and inverse design methods of coil and the calculation method of the coupling effect under the ferromagnetic boundary of magnetic shield are explained in detail, and their applications, especially in magnetocardiography (MCG) and magnetoencephalogram (MEG), are also mainly described. In conclusion, the unresolved challenges of different enhancement methods in materials preparation, optimization of practical implementation, and future applications are proposed, which provide comprehensive and instructive references for corresponding research.

Production of cost-effective green energy using Mn/Gd co-substituted cobalt ferrites hydroelectric cells and their oxygen evolution reaction

A thorough investigation into hydroelectric cells (HECs) composed of spinel ferrites, aiming to generate environmentally friendly electricity through the dissociation of water molecules into H3O+ and OH- ions without producing any harmful by-products has been reported. Utilizing a modified sol-gel auto-combustion synthesis method, we synthesized highly porous Mn2+/Gd3+ co-substituted cobalt ferrites (CFO) with the formula) [Co1-xMnxFe2-yGdyO4, 0≤x≤0.30 and y = 0.10]. X-ray diffraction (XRD) analysis revealed a singular-phase cubic structure, while Rietveld refinement provided essential parameters such as crystallite size, lattice constant, density, porosity percentage, and unit-cell volume. Morphological examination using Field emission scanning electron microscopy (FESEM) confirmed nanoparticle formation with an average size of 60.418 nm, and porosity increasing from 30 % to 51 % with Mn2+ ion doping, indicating enhanced water adsorption. XPS analysis highlighted increased lattice defects due to Mn/Gd co-substitution, boosting water adsorption capacity. Vibrating Sample Measurements showed a rise in Ms value with increasing Mn2+ concentration. Fabricated HECs delivered a maximum output current density of 13.906 mA/cm2, with 20 % Mn-substituted gadolinium cobalt ferrites-based HEC achieved a peak short-circuit current of 9.16 mA. These cells exhibited pseudo-capacitive behaviour, characterized by rapid and reversible faradaic reactions near electrode surfaces, while ionic diffusion mechanisms confirmed ion diffusion over the material's surface. Co1-xMnxGd0.1Fe1.9O4 (x = 0.20) is the optimal composition to get best OER performance having an overpotential of 342 mV at 10 mA/cm2 with a Tafel slope of 48 mV/dec in alkaline medium. This study underscores the potential of Mn2+/Gd3+ co-substituted cobalt ferrite as a promising alternative in green energy conversion applications, potentially replacing conventional fuel and solar cells. It has been concluded that the x = 0.20 is the composition that exhibits the best OER as well as HEC performance.

Synthesis of spinel ferrites from cashew gum for microwave devices application

Synthesis of spinel ferrites from cashew gum for microwave devices application

Elaboration and characterization of Zn1−xCoxFe2O4 spinel ferrites magnetic material: application as heterogeneous catalysts in styrene oxidation

Elaboration and characterization of Zn1−xCoxFe2O4 spinel ferrites magnetic material: application as heterogeneous catalysts in styrene oxidation

Investigation of the Dielectric Characteristics of Chromium-substituted Zinc and Cobalt Nanoferrite Systems

Abstract The series of Cr-substituted Zn and Co nanoferrite systems having the chemical composition CrxZnFe2–xO4 and CrxCoFe2–xO4 (0.0 ≤ x ≤0.5) were prepared by sol–gel technique. The present investigation aims to compare the impact of Cr3+ concentration on dielectric characteristics of Zn and Co-nanoferrite systems. The investigation of various dielectric characteristics was conducted using an LCR meter at 1kHz frequency and across the frequency range of 100Hz to 1MHz. The measurements were conducted at room temperature. In the case of both ferrite systems, the plots of frequency Vs dielectric constant (ε′) and AC conductivity (σac) show a common dielectric behavior of spinel ferrites. The plots of frequency Vs dissipation factor (D) of Cr- Cr-substituted zinc and Cobalt nanoferrite samples were observed to be unusual and display a relaxation peak at a particular frequency. In the current study, CrxZnFe2-xO4(x=0.2 and 0.3) and CrxCoFe2–xO4 (x=0.3) ferrite samples were found to exhibit very high values of dielectric constant. So these ferrites may be useful for a wide range of applications in electrical storage devices. According to LCR reports, all the Cr3+ substituted ferrite samples in both ferrite systems exhibit higher dielectric constant and AC conductivity values. Possible mechanisms that may be accountable for the outcomes are thoroughly scrutinized in this paper.

Investigation and estimation of structural and dielectric properties of chromium-doped cobalt ferrites nano particles

Abstract Nano ferrite materials are of critical importance in meeting the global demand for microwave and electronic devices, as spinel ferrites possess remarkable morphological, structural, and dielectric characteristics. This study investigates chromium-doped ferrite nanoparticles with the chemical composition CoCrxFe2-xO4 (x = 0.00, 0.30, 0.60, and 0.90), synthesize using the sol–gel technique and subjected to annealing at 900 °C. Energy Dispersive x-ray Analysis EDAX patterns confirmed compositional stoichiometry. X- Ray Diffraction analysis reveals that all samples exhibit a cubic crystal structure. Replacing some of the ions with chromium (Cr3+) led to a decrease in the x-ray density form (5.329–5.324). The average crystallite size in the fabricated samples ranged from 46.07 to 31.84 nm, and the lattice parameters decrease from 8.382 to 8.364 Å as the chromium content increase. Infrared spectra show that lower frequency band (ν2) at around 479.69-392 .60 cm–1 and a higher frequency band (ν1) within a range from 611.05–57661 cm–1 a clear indication of spinel structure characteristics. The examination using FE-SEM indicates that the produced materials exhibit porosity and amorphous characteristics. The significant tangent loss observe at lower frequencies suggests that these materials may have potential applications in medium-frequency devices. Consequently, spinel nanoferrites can offer advantages for advanced electronic and microwave technologies.

Retraction Note: The structural, dielectric and magnetic study of cobalt based spinel ferrites and polypyrrole composites

Retraction Note: The structural, dielectric and magnetic study of cobalt based spinel ferrites and polypyrrole composites

Nanostructured spinel ferrites: A comprehensive study on the synthesis, characterization, and magnetic properties of Zn and Mn substituted magnetite nanoparticles produced through the co-precipitation method

Seven cubic spinel ferrite nanoparticles were successfully synthesized through the co-precipitation method. These nanoparticles include Fe3O4, Zn0.4Fe0.62+Fe23+O4, Mn0.4Fe0.62+Fe23+O4, Zn0.6Mn0.4Fe0.42+Fe1.63+O4, Zn0.4Mn0.6Fe0.42+Fe1.63+O4, Zn0.4Mn0.4Fe0.22+Fe23+O4, and Zn0.4Mn0.4Fe0.42+Fe1.83+O4. The Rietveld method was used to analyze X-ray diffraction data, confirming that all samples have a single-phase cubic spinel structure. The presence of zinc and manganese ions in magnetite lattice leads to changes in lattice parameters and crystallite size, resulting in a range of 7–12 nm crystallite sizes. Fourier transform infrared spectroscopy (FT-IR) analysis of nanoparticles reveals two significant adsorption peaks at 560-576 cm−1 and 437-449 cm−1, corresponding to metal ion stretching vibrations at tetrahedral and octahedral sites. The X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of iron, zinc, and manganese in various oxidation states. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images showed spherical, agglomerated nanoparticles. The study confirmed the elemental composition and mapping images of prepared samples using energy-dispersive X-ray spectroscopy (EDS). The magnetic properties of the synthesized nanoparticles were meticulously examined utilizing a vibrating sample magnetometer (VSM) at room temperature. A direct correlation is established between the structural alterations induced by Zn2+/Mn2+ and their subsequent effects on magnetic characteristics, specifically through the reallocation of cations and the mechanisms of electron hopping occurring at the B-sites. The structural modifications result in enhanced superparamagnetic behavior, exhibiting saturation magnetization values between 46.01 and 69.38 emu/g. The sustainable characteristics of these materials render them highly viable options for applications in environmental remediation and green technology.

Synthesis, characterisation and functionalization of Hercynite nanoparticles for improved antibacterial activity

Hercynite i.e.,FeAl2O4 is an earth-abundant spinel mineral with a cubic crystal structure and belongs to the normal spinel ferrites possessing optical absorption in the visible range as well as superior magnetic and thermal properties. Herein, we synthesized nanosized FeAl2O4 where the citric acid-mediated sol–gel auto-combustion method was employed to achieve its pure phase and studied its physicochemical properties. Furthermore, the superior colloidal dispersion stability of the FeAl2O4 nanoparticles was achieved required for antibacterial activity and standardised via post-synthesis surface functionalisation using amino-propyl-triethoxysilane (APTES). We further characterised the material using states of art characterisation techniques for their structural, morphological, optical and thermal properties. Finally, the antibacterial activity of pure and surface functionalised FeAl2O4 nanoparticles was investigated against the Escherichia coli (E. coli) strain. We observed good penetration of surface functionalised FeAl2O4 nanoparticles into the bacterial membranes due to the high degree of dispersion achieved via cationic surface charge. Conclusively, a key finding of this study is the enhanced antibacterial properties of surface functionalised FeAl2O4 nanoparticles for the concentration of 31 µg/mL compared to pure FeAl2O4 nanoparticles at 62 µg/mL. This study has great relevance in the area of wound healing and tissue regeneration in the future.

Magnetic zinc ferrite nanostructures: Recent advancements for environmental and biomedical applications

Fabrication of spinel ferrite nanomaterials has gained immense attention in environmental and biomedical applications owing to their excellent magnetic properties. Among different spinel ferrites, zinc ferrite (ZnFe2O4) nanomaterials are promising transition metal oxide ferrites with excellent magnetic properties and biocompatibility. This review discusses the size and morphology-dependent physicochemical properties of ZnFe2O4 nanostructures and their correlation with the environmental and biomedical fields. Next, we provide a comprehensive overview of various synthesis and characterization techniques for fabricating ZnFe2O4 nanostructures. Examples of ZnFe2O4 nanomaterials and their nanocomposites used for environmental remediation, drug delivery, cancer theranostics, anticancer activity, imaging, biosensing, and gene therapy are further discussed. Finally, this review article offers insights into ZnFe2O4 nanostructures with their impacts, opportunities, and challenges for the future progress of environmental and biomedical applications.

Studying the Defects in Spinel Compounds: Discovery, Formation Mechanisms, Classification, and Influence on Catalytic Properties.

Spinel ferrites demonstrate extensive applications in different areas, like electrodes for electrochemical devices, gas sensors, catalysts, and magnetic adsorbents for environmentally important processes. However, defects in the real spinel structure can change the many physical and chemical properties of spinel ferrites. Although the number of defects in a crystal spinel lattice is small, their influence on the vast majority of physical properties could be really decisive. This review provides an overview of the structural characteristics of spinel compounds (e.g., CoFe2O4, NiFe2O4, ZnFe2O4, Fe3O4, γ-Fe2O3, Co3O4, Mn3O4, NiCo2O4, ZnCo2O4, Co2MnO4, etc.) and examines the influence of defects on their properties. Attention was paid to the classification (0D, 1D, 2D, and 3D defects), nomenclature, and the formation of point and surface defects in ferrites. An in-depth description of the defects responsible for the physicochemical properties and the methodologies employed for their determination are presented. DFT as the most common simulation approach is described in relation to modeling the point defects in spinel compounds. The significant influence of defect distribution on the magnetic interactions between cations, enhancing magnetic properties, is highlighted. The main defect-engineering strategies (direct synthesis and post-treatment) are described. An antistructural notation of active centers in spinel cobalt ferrite is presented. It is shown that the introduction of cations with different charges (e.g., Cu(I), Mn(II), Ce(III), or Ce(IV)) into the cobalt ferrite spinel matrix results in the formation of various point defects. The ability to predict the type of defects and their impact on material properties is the basis of defect engineering, which is currently an extremely promising direction in modern materials science.

Effects of Cr Substitution on the Structural, Optical, and Electrical Properties of Mg-Co Spinel Ferrites Synthesized via the Sol–Gel Method

Effects of Cr Substitution on the Structural, Optical, and Electrical Properties of Mg-Co Spinel Ferrites Synthesized via the Sol–Gel Method

Optimization of structural, optical, dielectric and magnetic properties of Gd3+ substituted Mg-Mn mixed spinel ferrite ceramics

Manganese magnesium ferrite (Mg0.5Mn0.5Fe2O4) and Gd doped Mg0.5Mn0.5Fe2O4 (Mg0.5Mn0.5Fe2-xGdxO4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized using the solid-state method. The structural study was performed using the powder X-ray diffraction (XRD) technique. The XRD plot confirms the presence of a spinel cubic structure for pure MgMn ferrite and the existence of a secondary GdFeO3 phase in addition to the cubic spinel phase for Gd-doped MgMn ferrite. The average crystallite size estimated from the Williamson-Hall plot decreases from 42.75 nm to 18.97 nm with the increase in Gd content. The microstructural study confirms the clear grains with well-defined grain boundaries. The Fourier Transform Infrared (FTIR) spectra of the samples show the vibrational bands at 3440 cm−1, 1636 cm−1, 1385 cm−1, 1100 cm−1, and 560 cm−1 assigned to tetrahedral and octahedral sites. The improvement in dielectric property has been observed for Gd-doped samples. The saturation magnetization and remnant magnetization decrease from 0.7 to 0.3 emu and 0.035 to 0.0273 emu respectively. The coercivity increases from 31 to 75 Oe with the increase in Gd content. The fabricated spinel ferrites have significant electrical and magnetic properties which may be promising candidates for microwave devices.

Hybrid CoFe2O4-CNTs-graphene: Synthesis and characterization for energy storage devices

Hybrid materials play a crucial role in a spectrum of energy storage devices. Among them CoFe2O4–CNT–graphene hybrid stands out as versatile magnetic materials with wide-ranging applications spanning electronics, magnetism, and sensor industries. In this study, we synthesized CoFe2O4–CNT–graphene hybrid utilizing ultrasonication method. This fabrication method resulted in the formation of CoFe2O4 nanoparticles, along with bamboo-like carbon nanotubes (CNTs) and graphene nanosheets which collectively establish an open three-dimensional structure. Thorough analyses were conducted on the synthesized nano-composites employing various characterization techniques such as XRD, FT-IR, Raman and FESEM. Further characterization through XPS confirmed the formation of spinel ferrites, detecting the presence of carbon sp2, C1s, carboxylates (O-C-OH), and sp3 carbon, indicating the presence of carbon‑carbon (CC) bonds and confirms the energy levels of Co2p1/2 and Co2p3/2 indicating the effective incorporation of CFO onto the CNT/graphene surface. Analysis of dielectric parameters revealed promising characteristics for high-frequency devices, attributed to low dielectric loss, high quality factor, short relaxation time, and diverse responses exhibited by these materials. The M–H loops of the composite samples displayed ferromagnetic hysteresis behavior due to the presence of ferrite in the matrices. The coercivity value shows a slight improvement in the hybrid samples, while saturation magnetization values decrease, indicating a 1:1 weight ratio of ferrite particles to the host matrix with the incorporation of nonmagnetic CNTs and graphene, and the Hc value increases with the addition of these carbon-based materials due to increased surface anisotropy energy. Upon evaluation of dielectric and magnetic properties the hybrid materials demonstrated an enhanced dielectric and magnetic properties which render these materials suitable for utilization across a spectrum of energy storage devices.

Effect of Zn-substitution on magnetic structure of cobalt ferrite nanoparticles.

This study investigates the effects of Zn substitution on the magnetic properties of ∼5nm cobalt ferrite nanoparticles (ZnxCo1-xFe2O4, where x = 0, 0.13, 0.34, and 0.55), demonstrating that Zn substitution induces complex changes in spin canting and prompts a redistribution of cations among the sublattices. We reconstructed the magnetic structure of these spinel ferrites by integrating the classical two-sublattice Néel model of ferrimagnetism with the data obtained from 57Fe Mössbauer spectrometry. Consequently, this research provides a comprehensive understanding of how Zn substitution tunes the magnetic properties of CoFe2O4 nanoparticles, offering valuable insights into the development of magnetic materials with tailored properties for various applications.

The Effect of the Calcination Time on the Microstructure and Properties of MnZn Ferrite Powders

MnZn ferrite powders were prepared based on the novel nano in situ composite method and through chemical sol-spray drying–calcination technology. The precursor powders were calcined at 1060 °C at different calcination times (1–9 h) to research the influences of the calcination time on MnZn ferrite powders. The research results revealed that all samples had similar morphologies composed of fine particles. The pure MnZn ferrite spinel phase can only be obtained when the calcination time does not exceed 3 h. Otherwise, some α-Fe2O3 or γ-Fe2O3 impurities will appear. The particle size descended with an increasing calcination time and then ascended. After 3 h of preservation, the smallest particle size was obtained, and it exhibited a unimodal distribution. The saturation magnetization (Ms) increased at first and decreased later with an increasing calcination time, and the optimal value (53.4 emu/g) was reached after holding for 3 h. In view of this work, the optimal calcination time is 3 h.

Microstructural, dielectric, electrical, electromagnetic, and magnetic property enhancements in GdIG /TrIG/ Mn0.2Co0.3Zn0.5Fe2O4 ferrites composites for electronic devices application

Gadolinium garnet ferrite (GdIG) and terbium garnet ferrite (TrIG), known for their favourable magnetic and dielectric characteristics, were combined with doped zinc spinel ferrite (GdIG)x-(TrIG)y/Mn0.2Co0.3Zn0.5Fe2O4(1-x-y) (at x=1 y=0, x=0 y=1, x=y=0.5, x=y=0.25, x=y=0) to achieve improved permittivity, permeability and magnetic properties with reduced magneto-dielectric losses. Our study details the synthesis process and the resulting enhancements in structural, magnetic, and dielectric properties of the prepared samples. Analysis of the X-ray diffraction (XRD) patterns confirmed the presence of a crystalline structure characterized by both cubic spinel and cubic garnet phases in the composites. The microstructures of the composites were analysed with field emission scanning electron microscopy (FESEM), revealing the variation in a grain size from 0.11 μm to 0.96 μm at x =y=0.5. A thorough link between the crystal structure and XRD spectra, transmission electron microscope (TEM), and selected area electron diffraction (SAED) patterns have all been investigated in order to enhance the characterisation of the samples. At 1KHz, the composites exhibit highest electrical resistivity values of 5.9×106 Ωm and 2.6×106 Ωm. With the incorporation of spinel ferrites in garnet ferrite composite (x=y=0.25) the highest value of dielectric constant (885.2) and low value of dielectric loss (0.07) at 100 KHz has been obtained. Permeability values, derived from permittivity data, showed an increase in real permeability values of from 1.4×1012 to 9.2×1017 for x=y=0.5 to x=y=0.25 composite. Vibrating sample magnetometer (VSM) further confirm that the composite x=y=0.25 has highest magnetic saturation (148.8 emu/g), coercivity (502 Oe) and microwave operating frequency (33.6 GHz). The observed high dielectric constant, low loss values, switching field distribution and good magnetic properties suggest the potential suitability of these samples for various electronic devices like: high frequency devices, antennas, switching devices and magnetic recording devices.