Superparamagnetic ZnFe 2 O 4 nanoparticles: The effect of Ca and Gd doping (original) (raw)
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MZnFe2O4 (M = Ni, Mn) cubic superparamagnetic nanoparticles obtained by hydrothermal synthesis
Journal of Nanoparticle Research, 2013
MZnFe 2 O 4 (M = Ni or Mn) cubic nanoparticles have been prepared by hydrothermal synthesis in mild conditions and short time without any procedure of calcinations. The structural and magnetic properties of the mixed ferrites were investigated by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Mössbauer spectroscopy, vibrating sample magnetometer, and Transmission electron microscopy (TEM). X-ray analysis showed peaks characteristics of the spinel phase. The average diameter of the nanoparticles observed by TEM measurements was approximately between 4 and 10 nm. Spectroscopy study of the spinel structure was performed based on Group Theory. The predicted bands were observed in FTIR and Raman spectrum. The magnetic parameters and Mössbauer spectroscopy were measured at room temperature and superparamagnetic behavior was observed for mixed ferrites. This kind of nanoparticles can be used as precursor in drug delivery systems, magnetic hyperthermia, ferrofluids, or magnetic imaging contrast agents.
Ferrites nanoparticles MFe2O4 (M = Ni and Zn): hydrothermal synthesis and magnetic properties
Boletín de la Sociedad Española de Cerámica y Vidrio, 2008
MFe 2 O 4 (M = Ni and Zn) nanoparticles were prepared by the hydrothermal method. The obtained samples were characterized by X-ray and electron diffraction, Scanning and Transmission Electron Microscopy and Mössbauer spectroscopy. The transmission images show homogeneous shape and particle size ranging from 10 to 40 nm, depending on the nature of the M cation. Mössbauer spectroscopy yields to a ratio of occupancy between the A and B sites of 0.7 in the case of NiFe 2 O 4 oxide. DC magnetization (2-300 K) measurements reveal a superparamagnetic behaviour for the ZnFe 2 O 4 sample with a blocking temperature of 20 K. By contrast, in the case of the NiFe 2 O 4 ferrite the blocking temperature appears to be above 300 K and at lower temperature, it shows a ferrimagnetic behaviour arising from the superexchange interactions that take place in this inverse spinel. Mössbauer spectroscopy results confirm the bulk magnetic measurements.
Journal of Magnetism and Magnetic Materials, 2007
In this paper, ZnFe 2 O 4 spinel ferrite nanoparticles with different grain sizes at different annealing temperatures have been synthesized using the starch-assisted sol-gel auto-combustion method. The synthesized nanoparticles were characterized by conventional powder X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and vibrating sample magnetometer. The X-ray diffraction (XRD) patterns demonstrated that the ZnFe 2 O 4 nanoparticles consist of single-phase spinel structure with crystallite sizes 4.
Ferrites nanoparticles MFe2O4 (M = Ni and Zn): Hydrothermal synthesis and magnetic properties
Boletin de la Sociedad Espanola de Ceramica y Vidrio
MFe 2 O 4 (M = Ni and Zn) nanoparticles were prepared by the hydrothermal method. The obtained samples were characterized by X-ray and electron diffraction, Scanning and Transmission Electron Microscopy and Mössbauer spectroscopy. The transmission images show homogeneous shape and particle size ranging from 10 to 40 nm, depending on the nature of the M cation. Mössbauer spectroscopy yields to a ratio of occupancy between the A and B sites of 0.7 in the case of NiFe 2 O 4 oxide. DC magnetization (2-300 K) measurements reveal a superparamagnetic behaviour for the ZnFe 2 O 4 sample with a blocking temperature of 20 K. By contrast, in the case of the NiFe 2 O 4 ferrite the blocking temperature appears to be above 300 K and at lower temperature, it shows a ferrimagnetic behaviour arising from the superexchange interactions that take place in this inverse spinel. Mössbauer spectroscopy results confirm the bulk magnetic measurements.
Journal of Sol-Gel Science and Technology, 2018
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, CoFe 2 O 4 , Zn 0.4 Co 0.6 Fe 2 O 4 , Cd 0.4 Co 0.6 Fe 2 O 4 , and Cd 0.2 Zn 0.2 Co 0.6 Fe 2 O 4 were successfully synthesized by using economical and simple microwavemodified 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 CoFe 2 O 4 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.
Hyperthermic and Relaxometric Properties of Cobalt Ferrite Nanoparticles
2021
Zinc substitution is often proposed as an efficient strategy to improve the performances of spinel ferrite nanoparticles, particularly related to their application as theranostic agents. In this work, a series of 8 nm spinel ferrite nanoparticles of formula CoxZnyFe3-(x+y)O4, is synthesized by thermal decomposition with the purpose of investigating the role of Zn 2+ ions in modifying the structural and magnetic properties. Contrary to most of the literature on this subject, where the sum of Co and Zn is kept constant (x+y=1), here the amount of Co is maintained at ca. x = 0.6, corresponding to the maximum of magnetic anisotropy of the Zn-undoped system, while the amount of Zn is progressively varied along the series from y = 0.05 to y = 0.4. This approach allows enlightening the effect of the Zn introduction on the magnetic and crystal structures and, particularly, on magnetic anisotropy, which is deeply investigated by several complementary techniques. A significant increase of the saturation magnetization, MS, upon the Zn-content up to y = 0.4 is confirmed only at low temperature, while at room temperature this effect is partially nullified by the weakening of the magnetic exchange coupling constants, due to the increasing Zn substitution. Moreover, we demonstrate that the lattice modifications following the Zn introduction are responsible of a strong decrease of the particle magnetic anisotropy. Overall, these effects limit the use of Zn-substituted ferrites in biomedical applications like MRI and magnetic fluid hyperthermia, only to very low amount of Zn, as here confirmed by relaxometric and calorimetric measurements.
Journal of Magnetism and Magnetic Materials, 2015
Superparamagnetic Zn 2 þ substituted manganese ferrite Mn 1 À x Zn x Fe 2 O 4 (x ¼ 0.3, 0.35, 0.4 and 0.45) nanoparticles (NPs) were synthesized via a direct, efficient and environmental friendly hydrothermal method. The synthesized NPs were characterized by X-ray powder diffractometry (XRD), transmission electron microscopy (TEM), thermo-gravimetry (TG) and vibrating sample magnetometry (VSM). The effects of various parameters such as the pH of reaction mixture, time and temperature of hydrothermal treatment and Zn substitution on the spinel phase formation, the magnetization, and the size of resulting NPs are discussed. The Zn 2 þ substituted manganese ferrite NPs obtained from hydrothermal process crystallized mainly in the spinel phase. Nevertheless, without citrate ions, the hematite phase appeared in the product. The monophase Zn 2 þ substituted manganese ferrite NPs hydrothermally prepared in the presence of citric acid had mean particle size of 7 nm and a narrow size distribution. Furthermore, the synthesized NPs can be used to prepare ferrofluids for biomedical applications due to their small size, good stability in aqueous medium (pH 7) and also high magnetization value.