Size Of Cobalt Ferrite Nanoparticles Research Articles

S-scheme CoFe2O4/g-C3N4 nanocomposite with high photocatalytic activity and antibacterial capability under visible light irradiation

Photocatalysts with bactericidal capabilities are taken much more into consideration due to the water disinfection aside from water purification Therefore, a magnetically separable CoFe2O4/g-C3N4 nanocomposite has been synthesized via a simple in-situ chemical method, and its performance in degrading methylene blue (MB), methyl orange (MO), and phenol has been investigated. Multiple characterization techniques were conducted to confirm the successful synthesis of cobalt ferrite (CF), graphitic carbon nitride (CN), and cobalt ferrite/graphitic carbon nitride (CF/CN) nanocomposites. The microscopy images indicated a great reduction in the size of CF nanoparticles in nanocomposites. The magnetic characteristics were studied by a vibrating sample magnetometer (VSM). CF showed a high magnetization value (41.4 emu/g) and by compositing CF with CN, the nanocomposite also showed considerable magnetic properties. Optical properties of the photocatalysts were analyzed and the results denoted that heterostructure formation between CF and CN led to better light absorption, reduction in the band gap energy, and enhancement of charge carriers separation. Among the different synthesized nanocomposites, 400 mg/L of the CF/25 wt% CN nanocomposite showed the best photocatalytic activity in 180 min by degrading 100% of MB. The Mott-Schottky analysis and the results of scavenging experiments divulged the superoxide radicals as the main active species along with proposing a S-scheme mechanism on the degradation pathway for CF/CN nanocomposite. The optimized nanocomposite demonstrated high stability after three cycles by over 98% degradation of MB. Eventually, the antibacterial feature of CF/25CN nanocomposite was assessed against Escherichia coli and Staphylococcus aureus bacteria and resulted in a magnificent performance by reducing 99.9% of both bacteria in 30 min.

One-step combustion synthesis of SiO2–CoFe2O4 nanocomposites and characterization for structural, thermal, optical and magnetic properties

In this study (1-x)SiO2-xCoFe2O4 (x = 0,0.2,0.4,0.8,1) nanocomposites were synthesized using the sol-gel auto-combustion route and structure, morphology, thermal, optical and magnetic properties of as-prepared samples were investigated. X-ray diffraction followed by Williamson-Hall analysis revealed the formation of pure cobalt ferrite (CFO) nanoparticles and SiO2-CFO nanocomposites. Scanning electron microscope (SEM) images showed that SiO2 matrix serves as a physical barrier to control the morphology and size of cobalt ferrite nanoparticles and prevents nanoparticles agglomeration. Diffuse reflectance UV–Vis spectroscopy analysis showed that the optical band-gap of SiO2-CFO nanocomposites decreases from 1.23 eV to 1.12 eV with increasing the concentration of cobalt. Finally, the vibrating sample magnetometer (VSM) analysis that as cobalt ferrite content increases, the magnetic properties of nanocomposites improved. These nanocomposites could be applicable as a magnetic photo-catalysts.

Ultrathin surface coated water-soluble cobalt ferrite nanoparticles with high magnetic heating efficiency and rapid in vivo clearance

To obtain magnetic nanoparticles with high magnetic heating efficiency and rapid in vivo clearance, this study utilized an improved linear response theory model to theoretically simulate the specific absorption rate (SAR) value versus the particle size of cobalt ferrite nanoparticles (CFNPs). An accurate SAR curve consistent with experimental results was obtained using cubes instead of spheres as the shape of CFNPs, given that cube was closer to the actual shape of prepared CFNPs. Under the guidance of simulation, we predicted and prepared water-soluble cubic CFNPs of 10–13 nm in size, with an ultrathin surface coating less than 1 nm in thickness. These CFNPs were experimentally verified to have high magnetic heating efficiency and rapid in vivo clearance rate. Our CFNPs of 11.8 nm in size had a high intrinsic loss power of 12.11 nHm2/kg. Most of the cells were killed within 30 min under magnetic heating with CFNPs. In an in vivo study, these CFNPs can heat a tumor area to 45 °C (ΔT > 9 °C) within 120 s under a weak alternating magnetic field (27 kA/m, 115 kHz). Notably, these CFNPs had significant tumor inhibition rate in vivo and can be cleared from the body by more than 64% within 2 weeks, demonstrating excellent rapid in vivo clearance. This result was close to the clearance level of the magnetic resonance imaging contrast agent Feridex. Therefore, our CFNPs had high magnetic heating efficiency and rapid in vivo clearance rate, indicating their great potential for future clinical applications.

The influence of synthesis parameters on one-step synthesized superparamagnetic cobalt ferrite nanoparticles with high saturation magnetization

Abstract In this study, superparamagnetic cobalt ferrite nanoparticles (SCFNs) were synthesized by co-precipitation in one-step. The synthesis parameters; reaction time and stirring rate, were varied separately while the other parameters were fixed constant to investigate the effect of the parameters on the properties of SCFNs. X-ray diffraction analysis and Fourier transform infrared spectroscopy confirmed that synthesized samples are cobalt ferrite. The magnetization consistently increased with the particle size as the reaction time increased and the stirring rate decreased. While the reaction time was effective on the size of the cobalt ferrite nanoparticles, the stirring rate was also found to have influence on the particle size and thus the magnetization of the nanoparticles. The critical size of cobalt ferrite nanoparticles for superparamagnetic limit with zero coercivity and remanence was found to be around 7 nm and its maximum magnetization value was 41.0 emu/g. When the size of the SCFNs went over 7 nm, the magnetization increased with a small coercivity of 2–5 Oe, which may offer a potential usage in magnetic hyperthermia applications. It was seen that structural properties, especially the particle sizes and corresponding magnetic properties of SCFNs were considerably affected by the parameters of stirring rate and especially reaction time. Therefore, it is seen that SCFNs with desirable properties can be tailored by changing the synthesis parameters and therefore may have the potential to use in biomedical applications.

Evaluation of the superparamagnetic and biological properties of microwave assisted synthesized Zn & Cd doped CoFe2O4 nanoparticles via Pechini sol–gel method

Recently, cobalt ferrite nanoparticles have attracted much attention due to their physical, chemical and magnetic properties. Numerous studies have focused on facile production of these nanoparticles. In this study, CoFe2O4, Zn0.4Co0.6Fe2O4, Cd0.4Co0.6Fe2O4, and Cd0.2Zn0.2Co0.6Fe2O4 were successfully synthesized by using economical and simple microwave-modified Pechini sol–gel method, calcined by microwave radiation. The nanoparticles were characterized by some techniques such as X-ray diffraction, energy dispersive spectroscopy, field emission scanning electron microscopy, Fourier transform infrared, and vibrating sample magnetometer analyses. The X-ray diffraction, energy dispersive spectroscopy and Fourier transform infrared results confirmed the formation of CoFe2O4 nanoparticles. Fourier transform infrared indicated two fundamental absorption bands of spinel structure. The diameters of the spherical and rod form structures of nanoparticles ranged from 18 to 39 nm. The results indicated that the substitution of Co with Zn and Cd in cobalt ferrite influenced the physical properties, magnetic properties and cytotoxicity of these nanoparticles as medical devices. Zn doping had the significant effect on decreasing the size of cobalt ferrite nanoparticles and improving the magnetic properties. Zn-doped nanoparticles exhibited super paramagnetic behavior (coercivity was nearly 0oe and saturation magnetization was 52.78 emu/g). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (in vitro cytotoxicity MTT assay) assay confirmed that all samples were non-toxic and potentially can be used in biomedical application.

Magnetodielectric composite with ferrite inclusions as substrates for microstrip patch antennas at microwave frequencies

A study has been conducted to estimate the complex permittivity and permeability along with magnetic characterization of different volume fractions of magnetodielectric composites with cobalt ferrite nano inclusions. Using an in touch superstrate technique dielectric properties are estimated. Cavity perturbation technique is used to study the complex permeability of the samples. 4πMs value and coercivity is measured using vibrating sample magnetometry. Structural and surface morphologies on the composite samples are conducted to determine the size and homogeneous distribution of nano inclusions. The average grain size of cobalt ferrite nanoparticles is found to be ∼10nm. The real part of permittivity and permeability of the samples varies from ∼1–2.905 to ∼1.01–1.05 with increase in inclusion content from 1%VF to 5%VF, respectively. The tanδ of permittivity and imaginary part of permeability is found to be of the order of ∼10−3 and ∼10−1 respectively. Verification of these composites as potential substrates for microstrip patch antenna is carried out by fabricating simple rectangular patch at 9.5GHz using transmission line model. Rectangular patch is designed on 5%VF composite system. The return loss for the composite system was found to be ∼−19.451dB which is comparable with that designed on standard glass epoxy substrate (ɛr=4.5).

Control of the Size of Cobalt Ferrite Nanoparticles : Synthesis and Properties

The preparation of a fluid of cobalt ferrite particles having a size varying from 2 to 5nm is described. This has been achieved by using functionalized surfactants. The size of cobalt ferrite particles decreases when the total reactant concentration decreases. The magnetic properties are described with magnetization curves and 57 Fe mossbauer spectroscopy. It is demonstrated that these particles are characterized by a superparamagnetic behavior.