Properties Of Cobalt Ferrite Nanoparticles Research Articles

Synthesis and influence of Zn substitution on optical and magnetic properties of cobalt ferrite nanoparticles by a polyacrylamide gel route

Synthesis and influence of Zn substitution on optical and magnetic properties of cobalt ferrite nanoparticles by a polyacrylamide gel route

The effect of apple pectin agent on the structural, magnetic, and optical properties of cobalt ferrite nanoparticles synthesized by the auto-combustion sol-gel method

In this investigation, in order to enhance the properties of cobalt ferrite magnetic nanoparticles, apple pectin was utilized as a natural additive during the sol-gel auto-combustion technique. Differential thermal analysis (DTA) and thermogravimetric (TGA) curves revealed that the initial temperature of the combustion process drops when apple pectin is present, indicating that this additive improves combustion conditions. The X-ray diffraction (XRD) patterns demonstrated that a cubic spinel structure of pure cobalt ferrite nanoparticles was formed in the presence of apple pectin without the existence of a secondary phase. Additionally, the structural parameters, including the lattice parameters, average crystallite size, and cation distribution between the tetrahedral and octahedral sites, were determined using the Rietveld refinement method. All the synthesized samples exhibited a mixed spinel structure based on the investigation of the cation distribution. A decrease in particle size and nanoparticle agglomeration was observed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, the magnetic properties were investigated. According to the experimental findings, the presence of 0.3 g apple pectin increased the saturation/remanence magnetization and coercivity of cobalt ferrite nanoparticles. The improvement in magnetic properties was correlated with the average crystallite size, cation distribution, and magnetic moment of the cations occupying the octahedral/tetrahedral sites. In addition, the diffuse reflectance spectroscopy (UV–Vis-DRS) results showed that the energy of the band gap varies from 1.54 to 2.21 eV in the synthesized samples.

Controlling magnetic and surface properties of cobalt ferrite nanoparticles: A comparison of co-precipitation and solvothermal synthesis methods

Cobalt ferrite (CoFe2O4) nanoparticles have been synthesized using two different wet-chemical methods: co-precipitation and solvothermal. Mesoporous cobalt ferrite nanoparticles were prepared using the co-precipitation method with 4, 6, and 8 wt% of Pluronic P123 and with the solvothermal method with 10, 15, and 20 wt% of PEG-4000. X-ray diffractometry confirmed the formation of a single-phase spinel structure. The saturation magnetization of the nanoparticles increased from 48 to 64 emu/g as the P123 concentration increased from 4 to 8 % wt, and decreased from 72 to 62 emu/g as the PEG-4000 concentration increased from 10 to 20 % wt. Generally, the samples synthesized by the solvothermal method had a higher specific surface area than those prepared by the co-precipitation method. In comparison to other samples, the 10 % PEG-4000 sample had the highest specific surface area and showed the highest level of dye degradation (93 %). The findings demonstrated that the concentration of Pluronic P123 and PEG-4000 had an impact on the saturation magnetization and specific surface area of the nanoparticles.

Effect of Manganese-Doping on the chemical and optical properties of cobalt ferrite nanoparticles

We report on the effect of manganese (Mn) doping on the structural, chemical and optical properties of cobalt ferrite (CFO) nanoparticles (NPs). The Mn(II)-substituted CFO NPs with variable chemical composition (Co1-xMnxFe2O4; x = 0.0–0.5; CMFO) were synthesized by an eco-friendly hydrothermal route. The CMFO NPs produced were with a crystallite size varying in the range of 8–14 nm, where the chemical valence state, chemical bonding, electronic structure and optical properties are strongly influenced by the Mn-substitution. The X-ray diffraction (XRD) studies revealed the Mn-substitution induced changes in CFO crystal structure. The Mn-substitution in CFO causes the lattice parameter enhancement (a), crystallite size increase, and micro-strain (ε) as evident in the XRD studies. The chemical composition driven direct, functional relationship reflected in a-D-ε correlation, which suggests the Mn-substitution allows the ability to control the size and strain in CFMO NPs. Chemical bonding analyses using Fourier transform infrared spectroscopy (FTIR) corroborates with structural assessment made with XRD studies. The MTd–O (MTd = metal ions in tetrahedral locations) absorption bands shifting to higher wavenumbers in FTIR studies indicate that, Mn-substitution induce changes in the metal cation distribution between the tetrahedral and octahedral locations of the ferrite lattice. The X-ray photoelectron spectroscopic (XPS) analyses indicate the presence of iron as Fe+3, cobalt as Co+2, and manganese in Mn+2 chemical state. With increasing Mn-content, the XPS revealed that the binding energy (BE) separation of Fe, as well as Mn, does not change compared to Co, indicating the chemical stability and valence state of Fe+3 and Mn+2 cations maintained well in the CMFO samples. While the overall chemistry of CFO is maintained, and is not influenced by the increasing Mn-concentration, the remarkable effect of Mn-substitution is seen on the optical properties of CFO NPs. The optical studies indicate that the band gap of CFO NPs exhibits a direct, functional dependence on Mn-concentration; the band gap varies in a wide range of 2.38–3.12 eV. The analyses indicate the exponential dependence of CFO optical band gap with Mn-content which provide a roadmap to engineer the materials with tunable band gap for desired technological applications.

Application of Taguchi method to optimize the properties of cobalt ferrite nanoparticles doped by Ca2+ and Gd3+

This study investigates the influence of Ca2+ and Gd3+ doping, coupled with crucial processing parameters on the properties of cobalt ferrite nanoparticles synthesized through the sol-gel auto-combustion method. A systematic exploration of these multifaceted effects was conducted using an L25 orthogonal array of the Taguchi method, facilitating the optimization of these parameters. X-ray diffraction (XRD) was utilized in conjunction with Rietveld refinement analysis to discern the structural properties and cation distribution present in the synthesized samples. This investigation yielded cobalt ferrite nanoparticles with an average crystallite size from 9 to 65 nm. Moreover, the microstructural analysis conducted using field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) demonstrated a significant influence of these parameters on the morphology and average grain size of the nanoparticles. Magnetic investigations revealed that saturation magnetization values varying from 44.94 to 89.92 emu/g. Remarkably, the Taguchi method optimized the synthesis conditions, establishing Ca2+ and Gd3+ doping concentrations of 0.032 and 0.03, pH at 6, a calcination time of 4 h, and a temperature of 800 °C. These settings yielded a sample exhibiting a uniform particle distribution and homogeneous morphology, marking it as a promising prospect for applications in the realm of biomedicine.

Effects of Ce3+ doping on the structural, magnetic and hyperfine properties of cobalt ferrite nanoparticles

Effects of Ce3+ doping on the structural, magnetic and hyperfine properties of cobalt ferrite nanoparticles

Structural and magnetic properties of cobalt ferrite nano-particles

This paper delves into the comprehensive study of the structural and magnetic properties of cobalt ferrite nanoparticles, magnetic Cobalt Ferrite nanoparticles were successfully synthesised by the sol–gel method using the needed precursors in the desired amount. The resultant CFO nanoparticle prepared is black, and XRD results say that the prepared cobalt ferrite has an average particle size of 37 nm which has been confirmed the same by HR-TEM. XPS confirmed the occupancy of cation at octahedral and tetrahedral site. RAMAN displays all its five modes, confirming the presence of cobalt ferrite. A vibrating sample magnetometer (VSM) was applied to determine magnetic characteristics at room temperature.

Tuning the magnetic properties of oleic-acid-coated cobalt ferrite nanoparticles by varying the surfactant coverage

Organic coatings on magnetic nanoparticles are extensively used in various applications. As demonstrated recently, these coatings affect the magnetic behavior of the nanoparticles. The modification of the magnetic properties of the nanoparticles and nanoparticle assemblies as the percentage of the oleic acid (OA) coverage of a cobalt ferrite nanoparticle increases, is investigated numerically using a multiscale modeling approach that combines density functional theory (DFT) and Monte Carlo simulations. The DFT calculations show that the increase in OA coverage results in a monotonic decrease of the mean magneto-crystalline anisotropy and in a reduction of the atomic magnetic moments and the exchange coupling constants in the nanoparticle. These effects are attributed to the gradual recovery of the bulk spinel structure at the coated surface, as the OA coverage increases. Input from the DFT calculations is used in the mesoscopic modeling for the study of the magnetic behavior of an assembly of these nanoparticles by employing the Monte Carlo simulations technique. The results demonstrate that despite the decrease of magnetic anisotropy, the coercive field increases with the increase in percentage of OA coverage in the assembly, in agreement with experimental findings. This study suggests the possibility of tailoring the magnetic properties of cobalt ferrite nanoparticles for high-performance applications by varying the organic coating concentration.

Investigating the modification in structural properties of cobalt ferrite nanoparticles with increasing annealing temperature

In this paper, we have investigated the variation in structural parameters with annealing temperature for cobalt ferrite nanoparticles prepared by a simple coprecipitation technique. The samples are characterized using XRD measurement. XRD data confirms that the cobalt ferrite nanoparticles possess a spinel structure for both annealing temperatures 430°C and 600°C. It also shows an impurity phase if the samples are annealed at 600°C. Different structural parameters such as lattice parameters, bond lengths, oxygen positional parameters, etc. are calculated in more detail from XRD data, which will elucidate the connection between annealing temperature and structural properties.

Correction to the paper "Synthesis and magnetic properties of cobalt ferrite nanoparticles formed under hydro and solvothermal condition"

Correction to the paper "Synthesis and magnetic properties of cobalt ferrite nanoparticles formed under hydro and solvothermal condition"

Reaction time-induced improvement in hyperthermia properties of cobalt ferrite nanoparticles with different sizes

Chemical reaction conditions involved in the formation of nanoscale materials can enormously affect their properties. However, the correlation between the reaction time (RT) and hyperthermia properties of magnetic nanoparticles (MNPs) is yet to be understood. Here, we synthesize cobalt ferrite magnetic nanoparticles (MNPs) using a thermal decomposition technique with different RT values. The variation in RT (70–180 min) is designed in such a way that the nucleation and growth process can be affected and improved considerably, achieving monodisperse spherical-like MNPs with superparamagnetic nature as confirmed by first-order reversal curve analysis. Hyperthermia properties are studied for cobalt ferrite MNP ferrofluids with different concentrations (1–5 mg/ml) at various magnetic field strengths (100–400 Oe). We obtain a maximum specific loss power (SLP) value of 510 W/g for MNPs synthesized using RT = 150 min. By extracting magnetic characteristic, we find a correlation between SLP and coercive field values as a function of RT, which can shed light on subtle changes in hyperthermia properties of MNPs.

Correction to the paper "Synthesis and magnetic properties of cobalt ferrite nanoparticles formed under hydro and solvothermal condition"

Correction to the paper "Synthesis and magnetic properties of cobalt ferrite nanoparticles formed under hydro and solvothermal condition"

Influence of Y3+ and La3+ ions on the structural, magnetic, electrical, and optical properties of cobalt ferrite nanoparticles

In the current study, nanocrystalline CoY0.5xLa0.5xFe2-xO4 (where x = 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10) ferrites have been synthesized via a sol-gel auto combustion process. The synthesized powders were pressed into pellet forms and sintered at 900 °C for 4 h in the air. X-ray diffractometry (XRD) confirmed the single-phase cubic spinel structure of the synthesized samples having the mean crystallite domain sizes ranging from 122 and 54 nm. FTIR spectroscopic analyses revealed two strong bands within the range of 600 to 350 cm−1, further confirming the cubic inverse spinel structure of the prepared materials. The surface morphologies and composition were investigated by Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray (EDX) Spectroscopy. The magnetic hysteresis curves recorded at room temperature exhibit ferrimagnetic behavior. The highest coercivity (Hc∼1276 Oe) was found at a high doping (x = 0.10) concentration of Y3+ and La3+ in cobalt ferrite. Dielectric constant increase with increased doping concentration whereas real-impedance and dielectric loss decrease with increased in doping concentration and applied frequency. The band gap energy increased from 1.48 to 1.53 eV with increasing Y3+ and La3+concentrations in the UV–Vis region. The elevated levels of magnetic and dielectric substances in the ferrite nanoparticles suggest that the material could be used for magnetic recording media and high-frequency devices.

Precipitating agent (NaOH and NH4OH) dependent magnetic properties of cobalt ferrite nanoparticles

This work investigates the effect of precipitating agents sodium hydroxide (NaOH) and ammonium hydroxide (NH4OH) on the structural and magnetic properties of cobalt ferrite nanoparticles. The co-precipitation method was used to synthesize cobalt ferrite nanoparticles (S1 and S2). The synthesized nanoparticles were characterized by techniques such as x-ray diffraction (XRD) and scanning electron microscopy (SEM) and using a vibrating sample magnetometer at temperatures of 10 and 300 K. XRD results confirm the formation of cobalt ferrite nanoparticles. SEM images revealed the formation of round-shaped particles with a diameter range of 10–20 nm. Crystallite size, saturation magnetization, coercivity, squareness ratio, and anisotropy constant depend on the precipitating agents. The values of saturation magnetization for S1 are 23.6 and 32.6 emu/g whereas those for S2 are 27.4 and 41.2 emu/g at 10 and 300 K, respectively. These nanoparticles can be explored for applications in the fields of magnetism and biomedical science.

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.

Effect of silica matrix on structural and optical properties of cobalt ferrite nanoparticles

Effect of silica on structural and optical properties of cobalt ferrite nanoparticles is investigated. Silica matrix helps to reduce nanoparticle agglomeration. X-ray diffraction (XRD) and UV–Visible (UV–Vis) spectroscopic techniques are employed. XRD reveals pure phase formation with material density varying from 2.37 g cm−3 to 0.85 g cm−3. Energy band gap shows an escalation (2.03 eV to 4.89 eV) for change in silica from 0% to 90%. An empirical formula for refractive index as μ = A(silica content)2+B(silica content)+C has been derived using theoretical fit. With increase in silica content, the refractive index, optical dielectric constant and dielectric susceptibility show decrements from 2.65 to 1.83, 6.0225 to 2.3489 and 0.4795 to 0.1870 respectively. The reflectivity, absorption coefficient, molar refractive index, molar electronic polarizability, reflection loss, polaron radius and optical basicity also show reduction. Dielectric polarizability, transmission coefficient and oxygen packing density show increment from 0.33 Å 3 to 11.19 Å 3, 0.6606 to 0.8416 and 40.2114 to 34.2266. Ionic concentration of silica, metallization criterion also show similar incremental trend. Observed effects have been attributed to the change in interparticle interactions, density and microstructure of the samples. Swift changes in parameters indicate their fine tuning through optimum magnitude of silica.

Structural and magnetic properties of cobalt ferrite nanoparticles doped with cadmium

The magnetization of CoFe2O4 nanoparticles is often less than the bulk value of 3.6 μB (86 emu/g), corresponding to an inverse distribution of cations in the spinel structure. This paper investigated the Cd doping on cobalt ferrite nanoparticles' structural and magnetic properties. Cobalt ferrite nanoparticles doped with cadmium (Co1-xCdxFe2O4, x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by using hydrothermal method. X-ray diffraction (XRD) analysis confirmed cubic spinel structure, and the crystallite size is estimated at around 56–59 nm. Micrographs obtained by scanning electron microscopy (SEM) showed an average particle size of about 60 nm, which is in agreement with the XRD analysis. The absorption band ν1 for samples obtained from the infrared spectrum (FTIR) varies from 586 up to 570 Cm-1 by Cd doping, indicating Cd's replacement on the tetrahedral site. Magnetization values of 71 and 81 emu/g are obtained for x = 0 and x = 0.1 samples, respectively. But the magnetization decreased as the amount of Cd doping further increased due to the decreasing superexchange interaction between tetrahedral and octahedral sites. The rearrangement of Fe3+ and Co2+ cations on tetrahedral and octahedral sites and spin disorder at the surface of nanoparticles can reduce the magnetization below the bulk value. The coercivity field (Hc) value of 1.1 kOe is obtained for the x = 0, and the Hc values decrease with Cd doping. This is due to the decreasing magnetocrystalline anisotropy by substituting cobalt with cadmium.

Influence of heat treatment on the crystallite size, structural, elastic, and magnetic properties of cobalt ferrite nanoparticles

Influence of heat treatment on the crystallite size, structural, elastic, and magnetic properties of cobalt ferrite nanoparticles

Tuning magnetic properties of cobalt ferrite nanoparticles by hematite amount

Tuning magnetic properties of cobalt ferrite nanoparticles by hematite amount

Effect of sintering on the various properties of cobalt ferrite nanoparticles

Cobalt ferrite nanoparticles with the structural formula CoFe2O4 were synthesized by the auto-combustion method to investigate structural and dielectric properties. The synthesized sample were calcined at 600°C at the heating rate of 5°C/min using the conventional heating. The calcined sample were taken in five equal proportions and then given conventional sintering at different temperatures of 700°C, 800°C, 900°C, 1000°C and 1100°C separately for 4 h at the same heating rate. X-ray diffraction spectra were obtained using Bruker D8 Advance X-ray Diffractometer and they confirmed the phase formation of all the samples. From the X-ray diffraction data, lattice constant, average crystallite size and theoretical density were calculated. The experimental density and porosity were also found out for all the samples. FTIR and dielectric properties such as dielectric constant, dielectric loss and impedance were studied. From the IR spectra, various metal-oxide bonds present in the samples were studied. The dielectric constant and dielectric loss were studied as a function of sintering temperature and frequency. Dispersive behaviour is observed for the variation of dielectric constant and dielectric loss with frequency. The dielectric constant was found to be increasing with the increase in sintering temperature in high frequency region. Possible mechanisms contributing to all the obtained results were being discussed.