Magnetic Properties Of CoFe2O4 Nanoparticles Research Articles

Preparation and Study of the Effect of pH Value on Structural, Morphological, Electrical and Magnetic Properties of CoFe2O4 Nanoparticles Prepared by Sol-Gel Precipitation Method

The present study reports the synthesis of cobalt ferrite nanoparticles (CoFe2O4 NPs) using the sol-gel precipitation process via mixing a stoichiometric ratio of cobalt chloride (1 M) and ferric chloride (2 M).. The molar of ferric to cobalt was mentioned (2:1) and then 2 M of sodium hydroxide was added. The structural and morphological features of the material were assessed using X-ray diffraction (XRD), Scanning electron microscopy (SEM), and atomic force microscopy (AFM). The electrical properties were analyzed using an LCR meter, while the magnetic properties were measured using a vibrating sample magnetometer (VSM). Fourier-transform infrared spectroscopy (FTIR) investigated the material's molecular vibrations. The X-ray diffraction (XRD) analysis revealed that all the samples exhibited a cubic spinal structure, and no additional peak was detected. Interestingly, the average size of the crystallites (D) decreased from 17.74 nm to 16.58 nm as the pH level increased from 7 to 13. This finding provides important insights into the behaviour of the tested samples under different pH conditions. The formation of the ferrite spine was confirmed by FTIR spectroscopy, with the primary detected bands (408.92 - 470.65 cm-1) attributed to the octahedral complexes and (516.94 - 588.31 cm-1) assigned to the tetrahedral ones. The dielectric and imaginary part of the dielectric constant decreased with increasing pH values excluding samples prepared at pH = 11. All samples with different pH values exhibit resonance peaks at frequencies up to (1 KHz). The magnetic measurements carried out by the VSM instrument, the result show that the saturation magnetization increases with increasing pH and the higher saturation magnetization is 68 emu. g1.

Effect of Cobalt Ion Concentration and Thermal Annealing Temperature on Structural and Magnetic Properties of CoFe2O4 Nanoparticles

Effect of Cobalt Ion Concentration and Thermal Annealing Temperature on Structural and Magnetic Properties of CoFe2O4 Nanoparticles

Synthesis, Analysis, and Characterizations to Investigate the Influence of Ni Dopant on the Structural and Magnetic Properties of CoFe2O4 Nanoparticles Confined Within the Mesoporous Silica SBA-15 Matrix

Synthesis, Analysis, and Characterizations to Investigate the Influence of Ni Dopant on the Structural and Magnetic Properties of CoFe2O4 Nanoparticles Confined Within the Mesoporous Silica SBA-15 Matrix

Characterization and magnetic properties of CoFe2O4 nanoparticles synthesized by the co‐precipitation method

AbstractIn this study, the characterization and magnetic properties of CoFe2O4 nanoparticles synthesized by co‐precipitation method were investigated. The calcined products obtained were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X‐ray (EDAX), Fourier transformed infrared (FTIR) spectroscopy, and vibrating sample magnetometer. Crystallite size and phase composition were analyzed by X‐ray diffraction. Crystallite size and phase composition were analyzed by X‐ray diffraction. The average crystallite size of CoFe2O4 nanoparticles increased in the range of 15.85–32.14 nm with an increase in temperature from 500 to 700°C. It was observed that spherical CoFe2O4 nanoparticles were produced. Synthesis of CoFe2O4 nanoparticles was confirmed using XRD, SEM‐EDAX, and FTIR analyses. The effect of crystallite size, calcination temperature, and lattice parameter on saturation magnetization, remanent magnetization, coercivity, and magnetocrystalline anisotropy were investigated by vibrating sample magnetometer. As the crystallite size value increased, magnetocrystalline anisotropy also increased.

Screening of Mono-, Di- and Trivalent Cationic Dopants for the Enhancement of Thermal Behavior, Kinetics, Structural, Morphological, Surface and Magnetic Properties of CoFe2O4-SiO2 Nanocomposites.

CoFe2O4 is a promising functional material for various applications. The impact of doping with different cations (Ag+, Na+, Ca2+, Cd2+, and La3+) on the structural, thermal, kinetics, morphological, surface, and magnetic properties of CoFe2O4 nanoparticles synthesized via the sol-gel method and calcined at 400, 700 and 1000 °C is investigated. The thermal behavior of reactants during the synthesis process reveals the formation of metallic succinates up to 200 °C and their decomposition into metal oxides that further react and form the ferrites. The rate constant of succinates' decomposition into ferrites calculated using the isotherms at 150, 200, 250, and 300 °C decrease with increasing temperature and depend on the doping cation. By calcination at low temperatures, single-phase ferrites with low crystallinity were observed, while at 1000 °C, the well-crystallized ferrites were accompanied by crystalline phases of the silica matrix (cristobalite and quartz). The atomic force microscopy images reveal spherical ferrite particles covered by an amorphous phase, the particle size, powder surface area, and coating thickness contingent on the doping ion and calcination temperature. The structural parameters estimated via X-ray diffraction (crystallite size, relative crystallinity, lattice parameter, unit cell volume, hopping length, density) and the magnetic parameters (saturation magnetization, remanent magnetization, magnetic moment per formula unit, coercivity, and anisotropy constant) depend on the doping ion and calcination temperature.

Towards hard-magnetic behavior of CoFe2O4 nanoparticles: a detailed study of crystalline and electronic structures, and magnetic properties.

We have used the coprecipitation and mechanical-milling methods to fabricate CoFe2O4 nanoparticles with an average crystallite size (d) varying from 81 to ∼12 nm when changing the milling time (t m) up to 180 min. X-ray diffraction and Raman-scattering studies have proved the samples crystalizing in the spinel structure. Both the lattice constant and residual strain tend to increase when t m(d) increases (decreases). The analysis of magnetization data has revealed a change in the coercivity (H c) towards the hard-magnetic properties. Specifically, the maximum H c is about 2.2 kOe when t m = 10 min corresponding to d ≈ 29 nm; beyond this t m(d) value, H c gradually decreases. Meanwhile, the increase of t m always reduces the saturation magnetization (M s) from ∼69 emu g-1 for t m = 0 to 35 emu g-1 for t m = 180 min. The results collected as analyzing X-ray absorption data have indicated a mixed valence state of Fe2+,3+ and Co2+ ions. We think that the migration and redistribution of these cations between the tetrahedral and octahedral sites together with lattice distortions and defects induced by the milling process have impacted the magnetic properties of the CoFe2O4 nanoparticles.

Effect of Oleylamine on the Surface Chemistry, Morphology, Electronic Structure, and Magnetic Properties of Cobalt Ferrite Nanoparticles.

The influence of oleylamine (OLA) concentration on the crystallography, morphology, surface chemistry, chemical bonding, and magnetic properties of solvothermal synthesized CoFe2O4 (CFO) nanoparticles (NPs) has been thoroughly investigated. Varying OLA concentration (0.01–0.1 M) resulted in the formation of cubic spinel-structured CoFe2O4 NPs in the size-range of 20–14 (±1) nm. The Fourier transform spectroscopic analyses performed confirmed the OLA binding to the CFO NPs. The thermogravimetric measurements revealed monolayer and multilayer coating of OLA on CFO NPs, which were further supported by the small-angle X-ray scattering measurements. The magnetic measurements indicated that the maximum saturation (MS) and remanent (Mr) magnetization decreased with increasing OLA concentration. The ratio of maximum dipolar field (Hdip), coercivity (HC), and exchanged bias field (Hex) (at 10 K) to the average crystallite size (Dxrd), i.e., (Hdip/Dxrd), (HC/Dxrd), and (Hex/Dxrd), increased linearly with OLA concentration, indicating that OLA concurrently controls the particle size and interparticle interaction among the CFO NPs. The results and analyses demonstrate that the OLA-mediated synthesis allowed for modification of the structural and magnetic properties of CFO NPs, which could readily find potential application in electronics and biomedicine.

Influence of Gd content on the structural, Raman spectroscopic and magnetic properties of CoFe2O4 nanoparticles synthesized by sol-gel route

The structural and magnetic properties of sol-gel synthesized Gd doped (x = 0.00 to 0.15) CoFe2O4 nanoparticles (NPs) have been studied. The x-ray diffraction (XRD) and FTIR spectroscopy along with Raman spectra confirmed the formation of face centered cubic inverse spinel structure. TEM images showed the NPs are well-dispersed with average particle size 30 nm. Room temperature magnetic measurement showed the value of coercivity fluctuates from 353 Oe to 1060 Oe for different % of Gd content. The maximum coercivity, saturation magnetization, magnetic moment, magnetic anisotropy, remnant magnetization found for 0.03% Gd content are 1060.19 Oe, 77.53 emu/gm, 3.29 μ, 4.11 × 104 erg/cm3, 32.38 emu/gm, respectively. The large value of coercivity indicated that the interparticle interactions and crystalline anisotropy are high. Thus CoFe2-xGdxO4 magnetic NPs might be a potential candidate for data processing, automotive and telecommunications.

Sol-Gel Route for the Synthesis of CoFe2-x Er x O4 Nanocrystalline Ferrites and the Investigation of Structural and Magnetic Properties for Magnetic Device Applications.

This study reports the formation of Er-doped nanocrystalline cobalt ferrite with the formula CoFe2–xErxO4 (0.0 ≤ x ≤ 0.10) from nontoxic metal precursors Co(NO3)2·6H2O, Fe(NO3)3·9H2O, and Er(NO3)3·5H2O through an easy and economical sol–gel route in which citric acid is served as the chelating agent. The as-prepared powder was annealed at 700 °C for 3 h in ambient air to get the required spinel structure. The annealed samples were subjected to structural and magnetic characterization. The X-ray diffraction (XRD) data of the samples confirmed the cubic spinel structure formation. The average crystallite size evaluated from XRD data increased from 21 to 34 nm with the substitution of Er due to the larger atomic size of Er3+ than Fe3+. Moreover, the crystallite size obtained from XRD data are well matched with the particle size measured from transmission electron microscopy images. The lattice parameters obtained from XRD data agree well with the values estimated from theoretical cation distribution and Rietveld refinement calculation. The hysteresis curve exhibits the particles are soft ferromagnetic and the coercivity increased from 54.7 to 76.6 kA/m with maximum saturation magnetization, Ms = 61 emug–1 for 0.10 Er content. The squareness ratios were found to be less than 0.5, which indicates the single-domain nature of our particles. The blocking temperature measured from field cooled-zero field cooled curves is TB > 350 K for all the samples, which is much higher than the room temperature (300 K). The enhancement of saturation magnetization and coercivity has been explained based on the crystallite size, anisotropy constant, and cation distribution. Thus, the structural and magnetic properties of CoFe2O4 nanoparticles (NPs) can be tuned by Er incorporation and these NPs can be applied in different soft magnetic devices.

Influence of Caffeine and Citrulline as New Fuels in the Magnetic Properties of Cofe2o4 Nanoparticles Synthesized by Gel Combustion

Influence of Caffeine and Citrulline as New Fuels in the Magnetic Properties of Cofe2o4 Nanoparticles Synthesized by Gel Combustion

Effects of Process Variables on Properties of CoFe2O4 Nanoparticles Prepared by Solvothermal Process

Controlling the morphology and magnetic properties of CoFe2O4 nanoparticles is crucial for the synthesis of compatible materials for different applications. CoFe2O4 nanoparticles were synthesized by a solvothermal method using cobalt nitrate, iron nitrate as precursors, and oleic acid as a surfactant. The formation of CoFe2O4 nanoparticles was systematically observed by adjusting synthesis process conditions including reaction temperature, reaction time, and oleic acid concentration. Nearly spherical, monodispersed CoFe2O4 nanoparticles were formed by changing the reaction time and reaction temperature. The oleic acid-coated CoFe2O4 nanoparticles inhibited the growth of particle size after 1 h and, therefore, the particle size of CoFe2O4 nanoparticles did not change significantly as the reaction time increased. Both without and with low oleic acid concentration, the large-sized cubic CoFe2O4 nanoparticles showing ferromagnetic behavior were synthesized, while the small-sized CoFe2O4 nanoparticles with superparamagnetic properties were obtained for the oleic acid concentration higher than 0.1 M. This study will become a basis for further research in the future to prepare the high-functional CoFe2O4 magnetic nanoparticles by a solvothermal process, which can be applied to bio-separation, biosensors, drug delivery, magnetic hyperthermia, etc.

Study of the Structural and Magnetic Properties of COFE2O4 Nanoparticles for Therapeutic Agent for Cancer Therapy

The cobalt ferrite (CoFe2O4) nanoparticles were synthesized by chemical co-precipitation technique and characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and Mössbauer spectroscopy. The CoFe2O4 nanoparticles coated with biocompatible chitosan at different concentrations to produce homogeneous suspensions were also characterized by dynamic light scattering (DLS) and hyperthermia set-up. XRD data of the sample explored the particle size near about 7 nm in as-dried condition. TEM micrograph of bare CoFe2O4 nanoparticles provided the particle size nearly too about 8 nm which is in good agreement with the XRD data. This particle size after coating with chitosan became 14 nm. EDX results of this sample confirmed its nano dimension with spinel structure. VSM results of the sample in as-dried condition showed the ferromagnetic character which has been beyond proved by Mössbauer spectroscopy. The hydrodynamic diameter (Hd) and polydispersity index (PDI) of the chitosan-coated samples also provided promising results. The samples were tested for their induction heating properties with an RF magnetic field of 20 mT and a frequency of 342 kHz. We also studied therapeutic efficiency in-vitro on 9L gliosarcoma cancer cells, which revealed > 98% of mortality through hyperthermia protocol with the same RF field and frequency using chitosan-coated CoFe2O4nanoparticles.
 GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 7, Dec 2020 P 69-75

Review on Recent Advances of Synthesis, Magnetic Properties, and Water Treatment Applications of Cobalt Ferrite Nanoparticles and Nanocomposites

Nowadays, CoFe2O4 (cobalt ferrite) nanoparticles have fascinated numerous researcher’s consideration because of their latent implementation in water treatment. CoFe2O4 nanoparticles are cost-efficient magnetic materials and are stable under diverse environments. Therefore, they are effortlessly removed from purified water by means of an external magnetic field and reclaimed for quite a lot of cycles. In this analysis, the focus was given on learning the influences of some aspects including calcination temperature, crystalline size, pH, synthesis method, and dopant type on the magnetic properties of CoFe2O4 nanocomposites and nanoparticles. The implementation of CoFe2O4 nanoparticles in water purification and its capability to be united with various nanoparticles for adsorption and photocatalysis were entirely conferred. The chance of retrieval and reprocess of CoFe2O4 nanoparticles and its nanocomposites were discussed. Finally, the holes which are still not built up for study in the modification of physical properties and further magnetic properties of CoFe2O4 nanoparticles for its complete usage in water treatment were delineated. Henceforth, using CoFe2O4 nanoparticles and its nanocomposites at trade scale for water treatment will definitely reduce the expenses of water as it uses visible light as the energy source and because of its capability to be recycled numerous times.

The effect of cation distribution on the magnetic properties of CoFe2O4 nanoparticles

CoFe2O4 nanoparticles were synthesized via a co-precipitation method at pH values of 9, 11 and 14. All synthesized samples were characterized using XRD, TEM, XANES and VSM. The XRD results indicate a pure phase of a cubic spinel CoFe2O4 structure at pH values of 11 and 14. They were found to contain a Fe2O3 impurity phase at pH 9. The crystallite size decreased with increased pH values and it was found to be in the range of 41–48 nm. The lattice constants also decreased with increased pH values corresponding to the theoretical lattice calculation. The average particle sizes are found to be in the range of 47.6–51.6 nm, which were observed in TEM images. The valence states and cation distribution of Fe and Co ions were examined using XANES and XPS techniques. XPS results show that the valences of Fe and Co ions in the samples are 3+ and 2+, respectively. The migration of Co2+ and Fe3+ ions between octahedral and tetrahedral sites fluctuated and the trend of those results depended on particle size. The saturation magnetization results depend on the cation distribution, particle size and an impurity phase. The sample at pH 11 showed the highest migration of Co2+ ions from octahedral to tetrahedral sites and obtained the maximum saturation magnetization value (71 emu/g). The law of approach to saturation magnetization was employed to find the cubic anisotropy constant (K1) of all samples.

Tailoring the Structural, Magnetic, Mechanical, and Thermal Properties of CoFe2O4 by Varying Annealing Temperature for High-Density Storage Devices

Nano-size particles of CoFe2O4 were synthesized by chemical co-preciptation method. Developed nano-particles were annealed at temperatures 300 °C, 500 °C, and 700 °C for 2 h to study the effect of annealing temperature on structural, mechanical, thermal, and magnetic properties of CoFe2O4 nanoparticles. For crystalline properties synthesized particles were characterized using powder X-ray diffraction (XRD) technique which confirms the formation of single-phase spherically shaped nanoparticles with crystallite size in the range from 13 to 32 nm. The micro-strain and dislocation-density decreased with increasing annealing temperature. The Fourier transform infrared (FTIR) absorption peaks experienced a blue shift with annealing temperature. The two-step decomposition process has been identified by the variation observed in thermal behavior. The saturation magnetization increased from 35.55 emu g−1 to 75.85 emu g−1 as we increase the annealing temperature from 300 °C to 700 °C. High coercivity and thermally stability of annealed CoFe2O4 nanoparticles make them suitable for high-density magnetic storage applications.

Influence of Zn-Zr substitution on the crystal chemistry and magnetic properties of CoFe2O4 nanoparticles synthesized by sol-gel method

The Zn-Zr co-substituted cobalt ferrite nanoparticles (CoZnxZrxFe2-2xO4, x = 0.0˗0.4) were synthesized by sol gel auto combustion route. The formation of cubic phase of Co ferrite was revealed from the X-ray diffractograms of the powder samples. The additional α-Fe2O3 and ZrO2 phases were occurred for ≥20% Zn-Zr substitution. The lattice parameters obtained by extrapolating Nelson–Riley function shows increase in its values with the Zn-Zr substitution. The particle size shows increasing trend with the Zn-Zr substitution. The cation distribution obtained from the Rietveld refinement of XRD estimate the equal preference of Zn ons preferred tetrahedral A site whereas most of the Zr ions occupy octahedral B site. The decrease in Fe ions with the Zn-Zr substitution resulted in the decrease in coercivity and saturation magnetization of the ferrites. Zero field cooled and field cooled magnetization plots of the ferrites reveals the ferromagnetic behaviour of the prepared ferrite samples. The blocking temperature does not vary significantly with the varying Zn-Zr substitution. The Mössbauer study confirms the weakening of the magnetic linkages between cations at A and B sites, due to the substitution of non-magnetic Zn-Zr ions for magnetic Fe ions. The decrease in coercivity with moderate saturation magnetization could make this material suitable for electronic devices.

Synthesis of cobalt ferrite nanoparticles with different morphologies via thermal decomposition approach and studies on their magnetic properties

Abstract CoFe2O4 nanoparticles have received immense attention in recent times due to their interesting magnetic properties and they possess good thermal and chemical stability. In the present study, CoFe2O4 nanoparticles have been synthesized via a novel thermal decomposition approach using Co–Fe glycolate precursors. The Co–Fe glycolates were prepared by refluxing the corresponding metal salts in ethylene glycol. The morphology of CoFe2O4 nanoparticles can be tailored by varying the synthesis temperature of Co–Fe glycolates and also the amount of ethylene glycol used. The morphology of CoFe2O4 changes from nanorods to hexagonal particles on changing the synthesis temperature of Co–Fe glycolates from 160 °C to 220 °C, On the other hand, on increasing the amount of ethylene glycol while keeping the synthesis temperature constant (220 °C), the morphology of CoFe2O4 nanoparticles changes from hexagons to octahedra. The Co–Fe glycolates and the CoFe2O4 nanoparticles were characterized using several analytical techniques. The magnetic properties of CoFe2O4 nanoparticles were studied by vibrating sample magnetometry. The CoFe2O4 nanoparticles exhibit high coercivity at 5 K with moderate saturation magnetization.

Magnetic Field Implementing into the Electroluminescence of OLED Devices Doped with CoFe2O4 Nanoparticles

Cobalt ferrite magnetic nanoparticles (CoFe2O4 MNPs) were successfully prepared by citric acid-assisted sol-gel auto combustion method and used in emissive layer of organic light emitting diode (OLED). Dimensional, structural and magnetic properties of CoFe2O4 nanoparticles (NPs) were recearched and compared by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). CoFe2O4 MNPs were utilized at various concentrations (0.5 wt%, 1.0 wt% and 2.0 wt%) in the emissive layer of the OLEDs. The luminance, current efficiency and the electroluminescence characteristics of the devices with and without CoFe2O4 MNPs were investigated. An external magnetic field, Bext, has also been applied to the OLEDs doped with MNPs while under operation. Effects of MNPs on OLED characteristics under Bext were studied thoroughly. In the tailored device architecture, poly (3,4-ethylenedioxythiophene): poly polystyrene sulphonate (PEDOT: PSS) and poly(2-methoxy-5-(2-ethylhexyloxy))-1,4-phenylene vinylene (MEH-PPV) were used as a hole transport layer (HTL) and an emissive layer respectively with ITO/PEDOT: PSS/ MEH-PPV: CoFe2O4/Ca/Al device architecture. The obtained results of the fabricated OLEDs were enhanced in the presence of CoFe2O4 NPs under Bext due to providing density of states in the polymer matrices. The turn-on voltage was diminished slightly in the device doped with 0.5 % wt MNP compared to the devices with other concentrations of MNPs.

Sucrose as a sol-gel synthesis additive for tuning spinel inversion and improving the magnetic properties of CoFe2O4 nanoparticles

Cobalt ferrite (CoFe2O4) nanoparticles were synthesized via the sol-gel method using varying quantities of sucrose as fuel. Thermal analysis shows the strong influence of the presence of the additive on the autoignition of systems. X-ray diffractograms indicate the successful formation of pure CoFe2O4 in all studied samples. As the sucrose concentration increased, crystallite sizes also increased, as shown via TEM, XRD and adsorption assays. TEM images also demonstrate the spherical tendency of the produced ferrites. Raman spectra show an increased tendency towards a normal configuration along increases in sucrose concentration. A redshift in the vibrational modes further indicates an increase in the number of vacancies in the structure, which were likely related to the reducing character of sucrose. These changes in the crystalline arrangement of the ferrites led to large variations in optical band gap energies, which increase with the addition of the carbohydrate. A maximum in coercivity of 1792 Oe was observed for the sample prepared with an initial sucrose concentration of 72 mmol L−1, which could be linked to the formation of single-domain nanoparticles. Magnetization increased with increasing sucrose additions. This phenomenon is a direct consequence of the cationic reshuffling caused by the presence of the carbohydrate.

Magnetic finite size effects, coercive field and irreversibility in sintered (1-x)BaTiO3–xCoFe2O4 nano-composites

We present detailed magnetic properties of (1-x)BaTiO3–xCoFe2O4 (x = 1, 0.5, 0.4, 0.3, 0.2, 0.1, 0.75, 0.05, 0.025) nanocomposites, synthesized through multiple-step chemical synthesis technique. Stepwise synthesis and structural optimization of composites include oxalate route synthesis of BaTiO3 with specifically chosen tetragonality followed by mixing in citric acid solution, and a final addition of the precursor for CoFe2O4. Heat treatment temperature were appropriately chosen to obtain composites with distinct spinel and tetragonal perovskite phases. Peak broadening has been observed in composites being a consequence of presence of strain. Main goal of the present work is to investigate magnetic response as a function of temperature for various compositions and to compare them with the magnetic properties of CoFe2O4 nanoparticles. BaTiO3 acts as a barrier for the growth of the CoFe2O4 due to the phase separation between these constituent phases in the composites. The nanoscopic features are consistently observed in the magnetic properties of the composites. These features include increase in coercivity, stronger temperature dependence of coercivity and magnetic irreversibility. CoFe2O4 and BaTiO3 composites exhibit strong temperature dependence with a more than an order of magnitude increase in coercivity at low temperatures.