Synthesis, structure and magnetic properties of CoFe<sub>2</sub>O<sub>4</sub> ferrite nanoparticles

Su, Kunpeng; Zhao, Chengxi; Wang, Haiou; Huang, Sha; Liu, Zhongwu; Huo, Dexuan

doi:10.1088/2053-1591/aabf7b

Cited by 15 publications

(8 citation statements)

References 31 publications

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“…TEM bright-field images, SAED pattern, and the size distribution plot are shown in Figure 1d-f. XRD and SAED patterns indicate that the nanoparticles synthesized contained only the ferrite phase, and the lattice parameters are in agreement with the reported values of CoFe 2 O 4 nanoparticles [30,31]. CoFe 2 O 4 nanoparticles have an irregular shape and considerable size distributions with an average size of 6.0 ± 1.0 nm.…”

Section: Structural and Magnetic Characterization Of Cofe 2 O 4 Nanop...supporting

confidence: 88%

Tailoring Interfacial Exchange Anisotropy in Hard–Soft Core-Shell Ferrite Nanoparticles for Magnetic Hyperthermia Applications

et al. 2022

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Magnetically hard–soft core-shell ferrite nanoparticles are synthesized using an organometallic decomposition method through seed-mediated growth. Two sets of core-shell nanoparticles (S1 and S2) with different shell (Fe3O4) thicknesses and similar core (CoFe2O4) sizes are obtained by varying the initial quantities of seed nanoparticles of size 6.0 ± 1.0 nm. The nanoparticles synthesized have average sizes of 9.5 ± 1.1 (S1) and 12.2 ± 1.7 (S2) nm with corresponding shell thicknesses of 3.5 and 6.1 nm. Magnetic properties are investigated under field-cooled and zero-field-cooled conditions at several temperatures and field cooling values. Magnetic heating efficiency for magnetic hyperthermia applications is investigated by measuring the specific absorption rate (SAR) in alternating magnetic fields at several field strengths and frequencies. The exchange bias is found to have a nonmonotonic and oscillatory relationship with temperature at all fields. SAR values of both core-shell samples are found to be considerably larger than that of the single-phase bare core particles. The effective anisotropy and SAR values are found to be larger in S2 than those in S1. However, the saturation magnetization displays the opposite behavior. These results are attributed to the occurrence of spin-glass regions at the core-shell interface of different amounts in the two samples. The novel outcome is that the interfacial exchange anisotropy of core-shell nanoparticles can be tailored to produce large effective magnetic anisotropy and thus large SAR values.

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Section: Structural and Magnetic Characterization Of Cofe 2 O 4 Nanop...supporting

confidence: 88%

Tailoring Interfacial Exchange Anisotropy in Hard–Soft Core-Shell Ferrite Nanoparticles for Magnetic Hyperthermia Applications

et al. 2022

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“…Simple hydrothermal synthesis yields non-mesoporous cobalt ferrite NPs of 34 nm with cubic/spherical shape and M s = 56.8 emu/g (300 K), and their non-porous nature makes them unsuitable as drug vehicles [42]. Using the co-precipitation-annealing (at 1000 • C) method [43] NPs of cobalt ferrite were formed with elongated morphologies (80-160 nm length and 43 nm width) exhibiting Ms = 43.7 emu/g, lower than the result afforded by the method reported here. Monodisperse mesoporous cobalt ferrite NPs obtained by a multi-step route involving a ligand-exchange method have been reported recently, but these exhibit inferior magnetic properties at ambient temperature (55.1 emu/g for CoFe 2 O 4 RNA, compared to our value of 68 emu/g) [44].…”

Section: Mössbauer Measurementsmentioning

confidence: 99%

Mesoporous Cobalt Ferrite Nanosystems Obtained by Surfactant-Assisted Hydrothermal Method: Tuning Morpho-structural and Magnetic Properties via pH-Variation

et al. 2020

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A facile and cheap surfactant-assisted hydrothermal method was used to prepare mesoporous cobalt ferrite nanosystems with BET surface area up to 151 m 2 /g. These mesostructures with high BET surface areas and pore sizes are made from assemblies of nanoparticles (NPs) with average sizes between 7.8 and 9.6 nm depending on the initial pH conditions. The pH proved to be the key factor for controlling not only NP size, but also the phase purity and the porosity properties of the mesostructures. At pH values lower than 7, a parasite hematite phase begins to form. The sample obtained at pH = 7.3 has magnetization at saturation M s = 38 emu/g at 300 K (54.3 emu/g at 10 K) and BET surface area S BET = 151 m 2 /g, whereas the one obtained at pH = 8.3 has M s = 68 emu/g at 300 K (83.6 emu/g at 10 K) and S BET = 101 m 2 /g. The magnetic coercive field values at 10 K are high at up to 12,780 Oe, with a maximum coercive field reached for the sample obtained at pH = 8.3. Decreased magnetic performances are obtained at pH values higher than 9. The iron occupancies of the tetrahedral and octahedral sites belonging to the cobalt ferrite spinel structure were extracted through decomposition of the Mössbauer patterns in spectral components. The magnetic anisotropy constants of the investigated NPs were estimated from the temperature dependence of the hyperfine magnetic field. Taking into consideration the high values of BET surface area and the magnetic anisotropy constants as well as the significant magnetizations for saturation at ambient temperature, and the fact that all parameters can be adjusted through the initial pH conditions, these materials are very promising as recyclable anti-polluting agents, magnetically separable catalysts, and targeted drug delivery vehicles.

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“…Hydrothermal synthesis led to bundles of CFO nanorods with a length of 120 nm . Rod-like CFO MNPs (lengths 80–160 nm; average width 43 nm) were obtained by coprecipitation and subsequent annealing, in the presence of some remaining spherical MNPs . In general, these procedures typically result in the formation of rather large CFO rods, and to the best of our knowledge, no synthetic routes are available for CFO-based nanorods with dimensions in the lower nanometer range (1–100 nm).…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties and Mössbauer Spectroscopy of Fe₃O₄/CoFe₂O₄ Nanorods

et al. 2020

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Fe 3 O 4 /CoFe 2 O 4 nanorods were obtained via a simple seed-mediated synthesis. Nanorods were used as seeds to grow CoFe 2 O 4 by thermal codecomposition of the cobalt(II) and iron(III) acetylacetonate precursors. The growth process was monitored by electron microscopy (SEM, TEM), and the resulting nanorods were characterized by powder X-ray diffraction analysis and IR and Raman spectroscopy. Magnetometry and AC susceptometry studies revealed a distribution of Neél relaxation times with an average blocking temperature of 140 K and a highfield magnetization of 42 Am 2 /kg. Complementarily recorded 57 Fe−Mossbauer spectra were consistent with the Fe 3 O 4 /CoFe 2 O 4 spinel structure and exhibited considerable signs of spin frustration, which was correlated to the internal and surface structure of the nanorods.

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Synthesis, structure and magnetic properties of CoFe₂O₄ ferrite nanoparticles

Cited by 15 publications

References 31 publications

Tailoring Interfacial Exchange Anisotropy in Hard–Soft Core-Shell Ferrite Nanoparticles for Magnetic Hyperthermia Applications

Tailoring Interfacial Exchange Anisotropy in Hard–Soft Core-Shell Ferrite Nanoparticles for Magnetic Hyperthermia Applications

Mesoporous Cobalt Ferrite Nanosystems Obtained by Surfactant-Assisted Hydrothermal Method: Tuning Morpho-structural and Magnetic Properties via pH-Variation

Magnetic Properties and Mössbauer Spectroscopy of Fe₃O₄/CoFe₂O₄ Nanorods

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Synthesis, structure and magnetic properties of CoFe2O4 ferrite nanoparticles

Cited by 15 publications

References 31 publications

Tailoring Interfacial Exchange Anisotropy in Hard–Soft Core-Shell Ferrite Nanoparticles for Magnetic Hyperthermia Applications

Tailoring Interfacial Exchange Anisotropy in Hard–Soft Core-Shell Ferrite Nanoparticles for Magnetic Hyperthermia Applications

Mesoporous Cobalt Ferrite Nanosystems Obtained by Surfactant-Assisted Hydrothermal Method: Tuning Morpho-structural and Magnetic Properties via pH-Variation

Magnetic Properties and Mössbauer Spectroscopy of Fe3O4/CoFe2O4 Nanorods

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Synthesis, structure and magnetic properties of CoFe₂O₄ ferrite nanoparticles

Magnetic Properties and Mössbauer Spectroscopy of Fe₃O₄/CoFe₂O₄ Nanorods