Spinel Ferrite Structure Research Articles

Enhancing Crystallinity and Magnetic Properties of Cobalt Ferrite Nanoparticles via Thermal Oxidation

AbstractCobalt ferrite (CFO) nanoparticles (NPs) are highly promising for data storage, energy conversion, permanent magnets, and biomedical applications owing to their exceptional magnetic properties. However, the presence of phase impurities (particularly FeO and CoO) can severely degrade their magnetic properties, hindering their practical use. Here, we present a simple post‐synthesis oxidation approach to address this challenge. Our method involves the thermal decomposition of Fe−Co oleate followed by oxidation using trimethylamine N‐oxide. The results reveal the effective elimination of FeO and CoO impurities and the formation of spinel ferrite crystal structures post‐oxidation with no change in morphology or size. Magnetic measurements demonstrate a significant enhancement in magnetic properties (e. g., magnetic saturation, coercivity, and blocking temperature) in oxidized CFO NPs compared to the non‐oxidized counterparts, indicative of the recovered ferrimagnetic structure upon post‐synthesis oxidation. As expected, the restoration of the ferrimagnetic structure, resulting in improved magnetic anisotropy, led to decreased SAR values as the nanoparticles moved away from the optimal anisotropy range. The study underscores the necessity of post‐synthesis oxidation for ensuring phase purity and enhancing the magnetic properties of CFO NPs, irrespective of the synthesis method. This approach offers a promising route for producing highly functional magnetic nanoparticles for practical applications.

Influence of Ni substitution on Structural, Optical, magnetic and transport properties of Mn0.5-xNixZn0.4Cu0.1Fe1.95Al0.05O4

A series of spinel ferrites Mn0.5-xNixZn0.4Cu0.1Fe1.95Al0.05O4 have been prepared by auto-combustion technique. X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) have been used for structural and morphological investigations. The XRD patterns confirm the formation of cubic spinel structure of ferrites. The lattice constants decrease with the increase of Ni contents due to the smaller ionic radii of Ni2+ compared to Mn2+ as well as particle size decreases. Density is increased and porosity is decreased with the increase of Ni contents in the samples due to the higher atomic weight of Ni2+ compared to Mn2+. The FESEM analysis reveal that the average size of the irregularly shaped grains increased with Ni contents. The mixed spinel structure is further confirmed by the FTIR spectra, which show a doublet band at about 600 cm−1. The observed optical band gap and the particle size variations are comparable, and the quantum size effect supports this conclusion. The real part of initial permeability and relative quality factor increase with the increase of Ni contents due to increase of density and grain size as well as decrease of porosity. Also, it is found that magnetic loss decreased with the increase of Ni contents. All the samples exhibit ferrimagnetic behavior and the number of Bohr magneton has been calculated for all compositions. The dielectric constant shows large value in the lower frequencies and decreases with frequency shows dispersion due to Maxwell-Wagner space charge polarization. The investigation of electric modulus has demonstrated the existence of the hopping conduction mechanism. The AC conductivity is very low at lower frequency region and very large at higher frequency region which can be explain according to the polaron hopping model of Austin and Mott. The AC conductivity enhances nearly linearly with frequency, suggesting that the mechanism of conduction is due to small polaron hopping, which can be described according to Jonscher’s power law. Also, the effect of grain and grain boundary resistance on transport properties has been investigated using complex impedance analysis and it has been observed that both exhibit an increase trend as the Ni content increases.

Magnetic nanoparticle-based combination therapy: Synthesis and in vitro proof of concept of CrFe2O4- rosmarinic acid nanoparticles for anti-inflammatory and antioxidant therapy.

Magnetic drug delivery systems using nanoparticles present a promising opportunity for clinical treatment. This study explored the potential anti-inflammatory properties of RosA- CrFe2O4 nanoparticles. These nanoparticles were developed through rosmarinic acid (RosA) co-precipitation via a photo-mediated extraction technique. XRD, FTIR, and TEM techniques were employed to characterize the nanoparticles, and the results indicated that they had a cubic spinel ferrite (FCC) structure with an average particle size of 25nm. The anti-inflammatory and antioxidant properties of RosA- CrFe2O4 nanoparticles were evaluated by using LPS-induced raw 264.7 macrophages and a hydrogen peroxide scavenging assay, respectively. The results showed that RosA- CrFe2O4 nanoparticles had moderate DPPH scavenging effects with an IC50 value of 59.61±4.52μg/ml. Notably, these nanoparticles effectively suppressed the expression of pro-inflammatory genes (IL-1β, TNF-α, IL-6, and iNOS) in LPS-stimulated cells. Additionally, the anti-inflammatory activity of RosA- CrFe2O4 nanoparticles was confirmed by reducing the release of secretory pro-inflammatory cytokines (IL-6 and TNF-α) in LPS-stimulated macrophages. This investigation highlights the promising potential of Phyto-mediated CrFe2O4-RosA as an anti-inflammatory and antioxidant agent in biomedical applications.

Multifunctional Characterization and Anticancer Properties of Magnetic Zinc Ferrite Nanoparticles by Modified Ultrasonic Assisted Co-precipitation Method

Zinc Ferrite (ZnFe2O4) nanoparticles were synthesized successfully via the modified ultrasonic-assisted co-precipitation method. Structural characterization, conducted through X-ray diffraction (XRD) analysis and Rietveld refinement, revealed a single cubic phase with a mixed spinel structure. Fourier transform infrared spectroscopy confirmed the presence of functional groups indicative of the spinel ferrite structure. Morphological analysis using field-emission scanning electron microscopy showcased the nanoparticles’ uniform morphology and size distribution. UV–vis spectra revealed the optical properties, while the Tauc Plot method determined the optical band gap. Electron paramagnetic resonance spectra confirm the symmetric resonance peak with 1254 Oe line width and the Lande g value 2.133. Magnetic hysteresis loops confirm the soft magnetic nature of the nanoparticles with magnetic saturation and coercivity of 39.2 emu gm−1 and 77.5 Oe. The anticancer properties against various cancer cell lines (HeLa, HepG-2 and MCF-7) revealed significant anticancer activity against HepG-2 and HeLa cells compared to MCF-7 cancer cells, and the results were compared with the standard drug cisplatin. A comparative analysis of results among cancer cell lines was conducted and discussed.

Facile sol–gel synthesis of trivalent Al3+-Gd3+ ions co-doped nanoscale cobalt spinel ferrite for magneto-electronic applications

The magnetic spinel ferrites nanomaterials simultaneously doped with multivalent cations have gained a lot of interest from many researchers during the last decade. Also, the doping of trivalent rare-earth ions in spinel ferrites is promising for many technological applications. Considering these facts, in this work we investigated the trivalent Al3+-Gd3+ ions co-doped cobalt ferrite nanoparticles with nominal composition as CoFe2-2xAlxGdxO4 (x = 0.00, 0.03, 0.05, 0.07, 0.10). The sol–gel auto ignition route assisted by citric acid as a chelating agent was utilized to synthesize the series of nanoparticles. The Rietveld refined X-ray diffraction (XRD) patterns were analyzed to ensure the single-phase formation of nanoparticles with spinel cubic structure. The spherical-shaped grain morphology of the nanoparticles was indicated by scanning electron microscopy (SEM) images. The elemental analysis obtained by energy dispersive X-ray analysis (EDAX) revealed stoichiometric formation of the samples along with high purity. The two prominent frequency modes analogous to the spinel ferrite structure were noted in the infrared spectra assuring the successful formation of all the samples. The soft magnetic behaviour with a lower coercivity of the prepared nanoparticles was confirmed by the vibrating sample magnetometer (VSM) technique. The DC electrical resistivity plots indicated that resistivity decreases with an increase in Al3+-Gd3+ co-doping. The dielectric studies of all the samples showed increasing behaviour with an increase in Al3+-Gd3+ co-doping. All the results suggest that the Al3+-Gd3+ co-doped cobalt ferrite nanoparticles can be useful for real-world applications, specifically in nanoelectronics devices.

Supercapacitor properties of Ni2+ incrementally substituted with Co2+ in cubic spinel NixCo1-xFe2O4 nanoparticles by sol-gel auto combustion method

The nanoparticle powder of Ni1-xCoxFe2O4 (x = 0.00, 0.25, 0.50, 0.75, 1.00) spinel ferrite was successfully prepared by the sol-gel auto-combustion method. The synthesized nanomaterials were used to prepare spinel ferrite supercapacitor electrode material. The structured phase of prepared nanoparticle powders was studied using XRD which shows the prepared sample consists of nanocrystalline single phase, with cubic spinel ferrite. Furthermore, using FESEM surface morphology of prepared samples was investigated. Ni1-xCoxFe2O4 nanoparticles spinel ferrite structure was verified by FT-IR, which detected distinctive vibrational bands at octahedral and tetrahedral locations.The spinel ferrite type materials are good active electrode materials. In this study, the prepared Ni1-xCoxFe2O4 electrode material is used as cathode material for supercapacitor. The electrochemical behavior of prepared samples was studied and compared by using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 1 M KOH electrolyte. An electrochemical measurement study of prepared samples shows excellent performance and desirable cycling stability for supercapacitors. The prepared Ni0.5Co0.5Fe2O4 spinel ferrite gives the highest specific capacitance of 1282 F/g at a current density of 5 mA/cm2 with corresponding energy density of 30 Wh/kg and power density of 301 W/kg. Also, they exhibited outstanding cycling stability for 5000 cycles with 91.24 % capacity retention.

Reduced graphene oxide nanosheets as electron sink for MnFe2O4 nanoparticles: A synergistically boosted supercapacitance

Spinel ferrite structures have shown promise for energy storage. However, they are insulators and need a conductive substrate for better charge transfer. Here, we utilized a simple hydrothermal technique to in-situ coat a nickel foam with few-layer nanosheets of reduced graphene oxide (rGO) decorated with manganese ferrite (MnFe2O4) nanoparticles. We then studied the supercapacitance/pseudocapacitance properties of the rGO/MnFe2O4 composite. X-ray diffraction patterns, energy-dispersive X-ray maps, and X-ray photoelectron spectra of the composite were investigated to confirm its structural, elemental, and surface chemical composition, respectively. Scanning electron microscopy and transmission electron microscopy images demonstrated the decoration of rGO nanosheets with MnFe2O4 nanoparticles. In a three-electrode setup, the rGO/MnFe2O4 nanocomposite exhibits a specific capacitance per loaded material mass (2446 F/g at 1 A/g) which is higher than the sum of rGO (304 F/g) and MnFe2O4 (1084 F/g) electrodes, suggesting a synergistic effect between rGO and MnFe2O4. The energy density and power density of the rGO/MnFe2O4 electrode were also calculated 58.24 Wh/kg and 260.82 W/kg (at 1 A/g), respectively. We found that the resistance of the rGO/MnFe2O4 electrode (2.53 Ω) is much lower than the MnFe2O4 electrode (6.15 Ω), and the interfacial resistance of the rGO/MnFe2O4 electrode with electrolyte was found low, confirming the rGO role as a conductive substrate for insulating MnFe2O4 nanoparticles. We also showed that surface-related capacitance, rather than pseudocapacitance, is more dominant in the rGO/MnFe2O4 composite electrode than in the separate rGO and MnFe2O4 electrodes. We also demonstrated the practical performance of the rGO/MnFe2O4 electrode in a two-electrode setup. Finally, density functional theory calculations showed the considerable potential drop (16.5 eV) between MnFe2O4 and graphene that leads to a strong built-in electric field from graphene towards MnFe2O4. This indicates the role of graphene as a wide electron sink for MnFe2O4 nanoparticles that results in better charge distribution and storage.

Rare Earth Nd3+ Doping Cobalt-Cadmium Nanoferrites Structural, Optical, and Magnetic Properties and Applications

Nanoscale particles of neodymium-substituted cobalt-cadmium generic formula for nanoferrite Co0.4Cd0.6NdxFe2−xO4 samples at X = 0.000, 0.003, 0.005, 0.007, 0.009, and 0.011 were studied. The prepared powders were synthesised at low temperatures using citrate gel auto-combustion process. The synthesised powders were calcined at 500 °C for four hours. The morphological properties of the sintered powders were investigated, and their crystal structure was determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD peaks confirmed the spinel ferrite structure. The lattice parameter was calculated from the XRD and showed decreasing trends with 8.442 to 8.308. SEM revealed an irregularly-shaped grain morphology with a homogeneous distribution. Raman spectroscopy analysis showed slight frequency changes in the Raman modes in doped samples, attributed to variations in the cation distribution. The peaks are located at 191, 291, 461, 591, and 671 cm−1. UV spectroscopy studies showed that the energy band gap values decrease with increasing Nd3+ concentration. Direct optical band gap values obtained were 1.238, 1.248, 1.199, 1.135, 1.134, and 1.101 eV with increasing Nd doping. The magnetic hysteresis properties were determined using a SQUID-VSM magnetometer. The hysteresis curves of Co0.4Cd0.6NdxFe2−xO4 nanoparticles show an increase in coercivity with increasing doping concentration. This enhancement is attributed to the multi-domain behaviour.

Determine elastic parameters and nanocrystalline size of spinel ferrites MFe2O4 (M = Co, Fe, Mn, Zn) through X-ray diffraction and infrared spectrum: Comparative approach

MFe2O4 (M = Co, Fe, Mn, Zn) nanoparticles were successfully synthesized by coprecipitation. Analyzing the X-ray diffraction by the Rietveld method confirmed the spinel ferrite structure of the samples. Rietveld refinement results show that Co, Mn and Zn occupy both the tetrahedral and octahedral sites. Variation in elastic parameters was determined by Fourier transform infrared spectroscopy, and cation distribution was deduced from X-ray diffraction. X-ray diffraction peak expansion was analyzed by employing a variety of calculating methods such as modified Scherrer, Williamson–Hall, size–strain, and Halder–Wagner to determine the crystallite size and elastic parameters of the cubic-structured MFe2O4 nanoparticles, including intrinsic strain, stress, and energy density. Comparison of the results obtained from these different methods revealed that they are ideally suited to each other. Moreover, the transmission electron microscopy image confirmed that the average size of MFe2O4 (M = Co, Fe, Mn, Zn) nanoparticles ranges from 10 to 14 nm, consistent with the dimensions obtained from the preceding methods.

Determination of low concentrations of glucose through colorimetric analysis using CoFe2O4 magnetic catalyst and SAT-3.

Natural enzyme mimics have attracted attention as alternatives to natural peroxidases. Among these, magnetic nanoparticles, especially ferrites, have attracted attention because of their unique electronic and physical structures, which are expected to be applied in various fields, including high-frequency magnetic materials, biomaterials, gas sensors, and semiconductor photocatalysts. The structural properties of the synthesized catalysts were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The prepared CoFe2O4 exhibited a spinel ferrite structure and formed a wood-flake-like bulk structure. In this study, magnetic CoFe2O4 was prepared using a precipitation method as a natural enzyme mimetic. CoFe2O4 showed excellent peroxidase-like activity, as demonstrated by the Michaelis-Menten constant (Km) and the maximum velocity (Vmax). The linear ranges of the calibration curves for H2O2 and glucose were in the range of 0-500µM, and the detection limits were 1.83 and 5.91µM, respectively. This analytical method was applied for the determination of glucose in human serum, and the results were satisfactory and consistent with certified values. The performance of this sensor was comparable to or superior to those of several other sensors commonly used for glucose analysis, indicating that its practical application is feasible.

Pemanfaatan Ekstrak Daun Sirih Hijau (Piper Betle Linn.) sebagai Capping Agent dalam Green Synthesis Spinel Ferit ZnFe2O4 untuk Remediasi Fenol dalam Air dan sebagai Anti Bakteri

The spinel ferrite material ZnFe2O4 was synthesized using a green synthesis approach by the hydrothermal method. In the synthesis, 2M NaOH was used as a mineralizer and betel leaf extract with varying volumes of 1, 3, 5, and 7 mL as a capping agent, then continued with calcination at 500, 600, and 700°C. Several devices, such as XRD, FT-IR, SEM-EDX, DRS-UV-Vis, and VSM, were used to characterize the synthesized ZnFe2O4 material. The pattern of XRD indicated that the ZnFe2O4 material has a cubic structure, where the increase in crystal size was after calcination. The Fourier Transform Infra-Red (FT-IR) spectrum shows the Fe-O interaction at wave numbers 427-417 cm-1, which is located on the octahedral side, while the Zn-O interaction at wave numbers 534-510 cm-1, which is located on the tetrahedral side in spinel ferrite structure. From the DRS UV-Vis spectrum pattern and band gap values, it was found that the material absorbs light in the visible region. Scanning Electron Microscope (SEM) images show that the morphology of the synthesized material is circular. The Vibrating Sample Magnetometer (VSM) hysteresis curve shows that the synthesized ZnFe2O4 has paramagnetic properties. The synthesized ZnFe2O4 material has photocatalytic activity towards phenolic compounds with a degradation percentage reaching 62.2%, and this material is active as an antibacterial with an inhibition area of 14.4 for S. aereus bacteria.

Production of Green energy via Water Splitting mechanism by Mn- doped Cobalt Ferrites [Co1-xMnxFe2O4] based Hydroelectric Cells

In our current study, we have investigated the impact of manganese (Mn) doping on the structural, magnetic properties, and hydroelectric cell properties of cobalt ferrite with chemical formula [Co1-xMnxFe2O4, x=0.00, 0.125]. The solid-state approach has been utilized to synthesize the material. XRDmeasurements revealed the formation of an inverse spinel cubic structure with the space group Fd-3m. FTIR spectra hold a shift in the octahedral and tetrahedral bands with the increase in Mn content in cobalt ferrites. The subsequent rise in ferroelectric behavior has been observed with the net maximum saturation polarization of 1.08μC/cm2. The variation in the permittivity values has been also studied with the increase in Mn content for dry as well as wet hydroelectric cells. The impedance measurements helped us understand the contribution of grains/grain boundaries in the prepared ferrites. The enhanced value of magnetization has been noticed from 48.258 emu/g to 73.089 emu/g upon doping of Mn ions in cobalt ferrite spinel structure lattice.The Mndoped CFO exhibited enhanced performance in hydroelectric cells which demonstrates the great ionic diffusion mechanism with the incorporation of Mn ions. The obtained output makes Mn doped CFO a suitable material for studying microelectronic and hydroelectric cell applications. The purpose of this study is to enhance both ferroelectric as well as ferromagnetic behavior along with the improved value of current in hydroelectric cells.

Unraveling the effect of annealing on the structural and microstructural evolution of NiFe2O4@SiO2 core-shell type nanocomposites

The comparison between as-received and multistage annealed NiFe2O4@SiO2 (NFO@SiO2) core-shell nanoparticles is presented. The studied ferrites were synthesized by co-precipitation followed by microemulsion. The presence of cubic inverse spinel ferrite structure with tetrahedral and octahedral iron occupancy is confirmed in all analyzed samples. The structural characterization revealed the gradual crystallization of NFO cores up to about 12 nm crystallite size at the last annealing stage. Simultaneously, a partial crystallization of the silica matrix is evidenced. The superparamagnetic (SPM) behaviour is demonstrated based on complex magnetic performance and confirmed by Mössbauer spectrometry. The spin-canting phenomenon on the surface dead magnetic layer (MDL) is revealed based on the Yafet-Kittel model. A slight change in MDL thickness versus heat treatment is proved. The X-ray photoemission and absorption studies confirmed the complex nature of the Fe-based states. The Si–O–Ni/Fe intermixing on the NFO – SiO2 nanoparticles interface is revealed by the core-level lines analysis, proving the existence of a disordered layer on the NFO surface.

Investigate structural, morphological, electrical, dielectric and magnetic properties of dysprosium doped Cobalt-Nickel ferrites and their response to gamma irradiation

Nanocrystalline Co1-xNixFe2-yDy0.5O4 ferrites were successfully prepared by the sol–gel auto-combustion method. The samples were gamma-irradiated using a cobalt-60 source. XRD analysis reveals the formation of cubic spinel structure. FTIR study is used to confirm the formation of the expected spinel ferrite structure. Two probe method was used to measure DC electrical resistivity and the Arrhenius relation was used to calculate activation energy for non-irradiated and irradiated ferrites. Frequency dependent dielectric properties of the non-irradiated and irradiated ferrites were studied at room temperature. The dielectric constant for most of the gamma-irradiated samples increases because defects are induced in the material which increases space charge polarization in the samples. Magnetic properties of non-irradiated and irradiated nano ferrites were studied using VSM. Coercivity decreases after irradiation because decrease in grain size which increases surface state pinning of the domains.

Assessment of Electromagnetic Shielding Efficacy of Magnetic Metal Oxide Nanoparticles and their Application in Electromagnetic Shielding Paints

AbstractPeople are continuously exposed to electromagnetic waves emitted by mobile phones, base stations, computers, household electrical appliances, and nearby devices. Shielding against electromagnetic radiation is of great importance to avoid potential adverse effects on human health. This study addresses the development of electromagnetic shielding paints containing magnetic metal oxide nanoparticles. Magnetic metal oxide nanoparticles with a spinel ferrite structure, namely Fe3O4, CoFe2O4, and SnFe2O4, were synthesized using the co‐precipitation method. Their structural, morphological, and magnetic properties were characterized through FTIR, XRD, TEM, and VSM measurements. Electromagnetic shielding efficacy was assessed within the 3.5–12.5 GHz frequency range using waveguide measurements. Notably, pure magnetic metal oxide nanoparticles exhibited limited shielding efficiency, but incorporating conductive materials like multi‐walled carbon nanotubes improved the efficacy. Optimization studies, involved adjusting the nanoparticle‐to‐carbon nanotube ratios and coating thickness, demonstrated the best shielding to be with 50 : 10 [MFe2O4:PEG]:mwcnt ratio (M : Fe, Co, Sn) and 0.720 mm thickness, achieving up to 99 % of radiation shielding. The subsequent incorporation of the optimized magnetic composites into a water‐based wall paint at a 1 : 2 weight ratio demonstrated their effectiveness in shielding, successfully blocking 84 % of incoming radiation.

Excellent microwave absorption of porous rod spinel by exceeding the Snoek limit via fibrosis and grain refinements

The fibrosis and nano-materialization of porous rod-shaped Co0.5Ni0.2Zn0.3Fe2O4 (C5N2Z3-C) spinel ferrite structure allowed it to exceed the Snoek limit and its EABmax reached 7.8 GHz (7.60 GHz–15.40 GHz) at only 2.8 mm.

Reusable magnetic mixture of CuFe2O4-Fe2O3 and TiO2 for photocatalytic degradation of pesticides in water.

Photocatalysis is a promising treatment method to remove pollutants from water. TiO2-P25 is a commercially available model photocatalyst, which very efficiently degrades organic pollutants under UVA light exposure. However, the collection and the recovery of TiO2-P25 from cleaned water poses significant difficulties, severely limiting its usability. To address this challenge, we have prepared a sintered mixture of TiO2-P25 nanomaterials and magnetic CuFe2O4-Fe2O3 nanocomposites. The mixture material was shown to contain spinel ferrite, hematite and maghemite structures, copper predominantly in Cu2+ and iron predominantly in Fe3+ state. The CuFe2O4-Fe2O3 and TiO2-P25 mixture demonstrated magnetic collectability from processed water and photocatalytic activity, which was evidenced through the successful photodegradation of the herbicide 2,4-D. Our findings suggest that the sintered mixture of CuFe2O4-Fe2O3 and TiO2-P25 holds a promise for improving photocatalytic water treatment, with the potential to overcome current photocatalyst recovery issues.

Characterization of Bi substitution of strontium cobalt zinc ferrites synthesized by micro-emulsion technique

Strontium cobalt zinc bismuth ferrites with formula are provided in this study using formula Sr0.5Co0.4Zn0.4BixFe2-xO4 at different variation of x= 0.0, 0.05, 0.10, 0.15 synthesized by Micro-emulsion techniques. To check the physical characteristics of this series (Sr0.5Co0.4Zn0.4BixFe2-xO4) of nano-ferrites using FTIR (Fourier Transformation of infrared spectroscopy), UV-visible, X-ray diffraction and scanning electron microscope. SEM and XRD analysis were used to examine the structure and morphology of manufactured nano-ferrites. The spectra of XRD demonstrated the production of a single-phase cubic spinel ferrite structure in the nanometer size range with no minor phase. When extending metal-oxygen bonds at tetrahedral and octahedral sites, FTIR analysis showed two bands centered at 592 and 410 cm-1 . Using ultraviolet-DRS, we determined that band-gap range for the synthesised magnetic materials was between 2.42 and 2.32 eV.

Structural, Mössbauer spectroscopy and magnetic study of Co1−xCdxFe2O4 ferrite synthesized by glycol-thermal method

The Cd2+ substituted Co1-xFe2O4 with concentrations of (0 ≤ x ≤ 0.7) nano ferrites were synthesized using the glycol-thermal method. X-ray diffraction (XRD) and Fourier-transformed infrared (FT-IR) spectroscopy confirmed the structural formation and nanocrystalline structure of spinel ferrites. Samples possess a cubic spinel lattice structure with crystallite sizes varying between 5.1 nm and 15.5 nm. Transmission electron microscopy (TEM) revealed fine particles which are nearly spherical in shape. The 57Fe Mössbauer spectral studies showed an ordered magnetic spin state for x ≤ 0.5 which transforms to a paramagnetic phase for x ≥ 0.6 due to the weakening of super-exchange interactions. The saturation magnetization (MS) was the highest at x = 0 with a value of 73.3 emu/g and fluctuated between 44.3 emu/g and 19.8 emu/g after the addition of non-magnetic Cd2+ ions. The field dependence of dM/dH curves reveals the finite size effect which leads to the frustration in magnetic moments.

Structural and magnetic properties of sol-gel autocombustion and microwave synthesized nickel ferrite nanoparticles and their photocatalytic and anti-microbial applications

Nickel Ferrite was synthesized from its nitrate precursors via sol–gel auto combustion method and microwave synthesis with ethylene glycol as fuel. The phase identification was carried out by XRD and the crystalline size was calculated. The Williamson- Hall plot was drawn and lattice strain and crystallite size was determined. The spinel structure of ferrite was confirmed using FTIR spectra. The morphology of samples were studied from HR-TEM. The UV–Visible spectra of samples were obtained and the band gap was determined from Tauc plot. The magnetic properties of samples were studied using VSM. The antibacterial activity of samples on Escherichia coli and Staphylococcus aureus was studied by well diffusion method. Their photocatalytic degradation of Methyl Orange under UV light was carried out and studied using UV–Visible Spectrophotometry.