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Journal ArticleDOI: 10.1016/J.JALLCOM.2020.157447

Ferro to superparamagnetic transition: Outcome of Ni doping in polyethylene glycol capped CoFe2O4 nanoparticles

05 Mar 2021-Journal of Alloys and Compounds (Elsevier)-Vol. 856, pp 157447
Abstract: Nanocrystalline CoFe2O4 and Ni doped CoFe2O4 were synthesized via chemical precipitation method and their crystal structure, energy gap and magnetic properties were investigated at room temperature. The results revealed that the Ni doping dropped the crystallite size from 23.4 to 6.9 nm. FTIR spectra confirmed the formation of ferrites through the vibrational bonds at 462 and 591 cm−1. UV–Visible diffuse reflectance spectra confirmed that the synthesized ferrite samples are wide bandgap material whose bandgap varies between 3.73 and 4.01 eV. Photoluminescence study confirmed the visible emission of the samples. Transmission electron microscopy analysis confirmed the formation of single domain size of ∼15–72 nm and the morphological tailoring from nanocubes to nanoparticles. Compositional analysis established the consistent mixing of Co, Ni, Fe, and O atoms. The hysteresis analysis confirmed that Ni dopant favours for the magnetic transition from ferro to superparamagnetism. It also infers that Ni dopant reduces the saturation magnetization of cobalt ferrite from 57.83 to 27.13 emu/g and decreased the coercivity from 0.1253 to 0.0139 T as x varies from 0 to 1. Electron paramagnetic resonance spectra confirm the increase in super exchange interaction with the increase in Ni concentration. The dielectric study inferred that the dielectric constant decreases with the increase in frequency.

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Topics: Superparamagnetism (56%), Ferrite (magnet) (54%), Nanocrystalline material (54%) ... read more
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7 results found


Journal ArticleDOI: 10.1007/S10854-020-04856-9
B. Alshahrani1, H. I. Elsaeedy1, S. Fares2, A. H. Korna2  +5 moreInstitutions (2)
Abstract: Herein, we used the ultrasound irradiation to assist the sol–gel method for the synthesis of spinel ZnCexFe2 − xO4 nanoparticles. The patterns obtained from energy dispersive x-rays (EDX) analysis and elements mapping demonstrate the appropriate elemental stoichiometry and spatial distribution in the prepared samples. The Rietveld refinement patterns revealed the successful synthesis of the cubic-structured ZnFe2 − xCexO4 without any secondary phases. The crystallite size of ZnFe2 − xCexO4 ranged from 7 to 11 nm. Also, the optical bandgap for ZnFe2 − xCexO4 decreased from 2.1 eV to 1.77 eV. Electron paramagnetic resonance (EPR) spectroscopy was used to study the ferromagnetic resonance (FMR) characteristics of the ZnFe2 − xCexO4 samples. The resonance field was increased from 3362.65 Gauss to 3401.76 Gauss, while the line width decreased from 598.90 to 455.72 Gauss. The saturation magnetization was enhanced from 2.43 emu/g for x = 0.00 to 9.38 emu/g for x = 0.02. In addition, the values of coercivity (Hc) and remanence magnetization (Mr) were significantly lowered. The great value of saturation magnetization together with low values of Hc and Mr of Ce3+-substituted Zn ferrites makes them potential candidates for the microwave absorption field.

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Topics: Ferromagnetic resonance (63%), Remanence (58%), Coercivity (56%) ... read more

10 Citations


Open accessPosted ContentDOI: 10.21203/RS.3.RS-271636/V1
05 Mar 2021-
Abstract: Cobalt ferrite (CoFe2O4) nanoparticles were synthesized through three different routes (chemical co-precipitation, ceramic, and sol-gel). The products were characterized by XRD, SEM, TEM, Raman spectroscopy, FTIR, photoluminescence (PL), BET, XPS, vibrating sample magnetometer (VSM). The X-ray analysis validates the spinel structure of the samples with particle sizes between 21 – 36 nm. XPS revealed the impact of the preparation route on cation distribution at the tetrahedral and octahedral sites in spinel ferrite lattice. All ferrite surfaces exhibit a mesoporous structure with a surface area between 25 – 99 m2/g. The results show that the prepared samples exhibit either ferromagnetic or super-paramagnetic behavior. The ferrite samples showed a photocatalytic performance under visible light. The present work demonstrates that each of the particle size and cation distribution is effective in controlling the structural, magnetic, and optical properties. The results obtained reveal that this kind of CoFe2O4 spinel ferrite nanoparticles has promising applications in magnetic designs and water treatment fields.

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Topics: Nanocrystalline material (54%)

Proceedings ArticleDOI: 10.1063/5.0061127
13 Sep 2021-
Abstract: In this work, we tried to investigate the structural properties of cobalt ferrite (CoFe2O4) nanoparticles synthesized via the sol-gel auto-combustion method. The synthesis of cobalt ferrite was carried out by glycine assisted auto-ignition in the sol-gel method. The preparation conditions and sintering temperature during the synthesis creates additional phases in the respective materials, which may play an important role in several applications because of their controlled physical properties. Therefore, CoFe2O4 nanoparticles were considered as a good candidate for high-frequency applications. The X-ray diffraction study of CoFe2O4 nanoparticles was carried out for phase purity. XRD pattern revealed the presence of Bragg's reflections which belong to the cubic spinel structure. The Miller indices (hkl) were identified using the standard method and the FWHM of the most intense peak (311) was used for the calculation of crystallite size. The crystallite size (t) was estimated using Debye-Scherrer's formula and found to be 32.16 nm which is following our expectations.

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Topics: Crystallite (52%), Nanoparticle (50%)

Journal ArticleDOI: 10.1142/S0218625X21500529
P. Priyadharshini1, K. Pushpanathan1Institutions (1)
Abstract: This paper focuses on the synthesis and structural, optical, and magnetic characterization of Mn-doped CoFe2O4 nanoparticles synthesized by a simple chemical co-precipitation method. Synthesized ma...

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Topics: Crystallite (52%)

Open accessProceedings ArticleDOI: 10.1063/5.0061089
13 Sep 2021-
Abstract: An effect of trivalent yttrium ion substitution on the structural properties of Co-Zn ferrite has been studied after the fabrication of Co1-xZnxFe2-yYyO4 nanoparticles at a typical concentration (x=0.3, y=0.2). The synthesis of Co1-xZnxFe2-yYyO4 nanoparticles was carried out via sol-gel auto-combustion technique using the citric acid as a fuel with a metal nitrate to citrate ratio of 1:3. X-ray diffraction studies of Co1-xZnxFe2-yYyO4 nanoparticles were carried out to study the structural parameter and phase purity. In this study, the XRD pattern revealed the presence of Bragg's reflections belongs to the cubic spinel structure. The Y3+ ion doping creates additional phases in the Co-Zn ferrite, which plays a crucial role in controlling the physicochemical properties of the typical samples. The crystallite size (t) was estimated using Debye-Scherrer's formula and reported to be decreased as a result of Y3+ ionic exchange as per the expectations. Y3+ ion substituted Co-Zn ferrite (with Y content = 0.02 per formula unit) may be considered for an attenuation application in the particular range. Visible range light was used for the photocatalytic degradation measurements using methylene Blue dye. In particular, an enhanced degradation efficiency of Co1-xZnxFe2-yYyO4 nanoparticles was observed. The UV-vis spectroscopic studies were performed and reported in the wavelength range 220 - 400 nm to check the absorbance of methylene blue dye at different time intervals.

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Topics: Ferrite (magnet) (54%), Yttrium (53%), Formula unit (51%) ... read more

References
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73 results found


Open accessBook
01 Jan 2001-
Topics: X-ray crystallography (53%)

19,319 Citations


Open accessBook
01 Jan 1956-
Abstract: 1. Properties of X-rays. 2. Geometry of Crystals. 3. Diffraction I: Directions of Diffracted Beams. 4. Diffraction II: Intensities of Diffracted Beams. 5. Diffraction III: Non-Ideal Samples. 6. Laure Photographs. 7. Powder Photographs. 8. Diffractometer and Spectrometer. 9. Orientation and Quality of Single Crystals. 10. Structure of Polycrystalline Aggregates. 11. Determination of Crystal Structure. 12. Precise Parameter Measurements. 13. Phase-Diagram Determination. 14. Order-Disorder Transformation. 15. Chemical Analysis of X-ray Diffraction. 16. Chemical Analysis by X-ray Spectrometry. 17. Measurements of Residual Stress. 18. Polymers. 19. Small Angle Scatters. 20. Transmission Electron Microscope.

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Topics: Selected area diffraction (62%), Electron backscatter diffraction (61%), Diffraction (57%) ... read more

17,396 Citations



Open accessJournal ArticleDOI: 10.1021/CR400544S
08 Jul 2014-Chemical Reviews
Topics: Nucleation (69%), Crystal growth (50%)

1,450 Citations


Journal ArticleDOI: 10.1016/J.JMMM.2011.10.017
Abstract: Magnetic ferrofluids (magnetic nanofluids) have received special attention due to their various biomedical applications such as drug delivery and hyperthermia treatment for cancer. The biological applications impose some special requirements. For example, the well-known iron oxide ferrofluids become undesirable because their iron atoms are poorly distinguishable from those of hemoglobin. A conceivable solution is to use mixed-ferrites (MFe2O4 where M=Co, Mn, Ni, Zn) to have a range of magnetic properties. These ferrites have attracted special attention because they save time, and because of their low inherent toxicity, ease of synthesis, physical and chemical stabilities and suitable magnetic properties. Based on the importance of ferrite particles in ferrofluids for hyperthermia treatment, this paper gives a summary on the physical concepts of ferrofluids, hyperthermia principal, magnetic properties and synthesis methods of nanosized ferrites.

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Topics: Ferrite (magnet) (52%)

519 Citations