A combined experimental and theoretical study of the magnetic properties of bulk CoFe2O4

Lamouri, R.; Fkhar, L.; Salmani, E.; Mounkachi, O.; Hamedoun, M.; Ali, Mustapha Ait; Benyoussef, A.; Ez‐Zahraouy, H.

doi:10.1007/s00339-020-03510-9

Cited by 35 publications

(14 citation statements)

References 27 publications

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“…From the (BH) max versus H plot in Figure b, we have obtained the maximum value of 2.4 MGOe for C-2. To the best of our knowledge, this (BH) max product at room temperature exceeds the values previously reported for CoFe 2 O 4 . , We have compared the (BH) max value of C-2 with other reports, and a comparative analysis is presented in Table S3. ,− …”

Section: Resultsmentioning

confidence: 55%

Spin Disorder and Particle Size Effects in Cobalt Ferrite Nanoparticles with Unidirectional Anisotropy and Permanent Magnet-like Characteristics

2020

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Spinel ferrites, especially cobalt ferrite, have the capability of preserving sufficient magnetization (M s) and coercive field (H c). However, precise nanostructuring is needed to sustain the steady ferrimagnetic (FiM) response with high H c and remnant magnetization (M r). By a two-step process involving co-precipitation and inert calcination, CoFe2O4 nanoparticles (NPs) with inherent lattice strain were achieved with appreciable magnetic anisotropy. The disordered spins on the NP surface are found to be the key for maintaining the anisotropy and squareness (M r/M s) of hysteresis loops, the extent of which is a function of the processing temperature and NP size. The freezing of surface spins results in 2.8 and 1.2 nm thick spin glass (SG) layers for the as-prepared and 350 °C-calcined CoFe2O4 NPs, respectively, analyzed at 5 K. The frozen surface spins pin the core FiM spins, resulting in the exchange bias (H eb) coupling. At room temperature, 20 nm NPs exhibit permanent magnet-like features with a maximum energy product, BHmax, of 2.4 MGOe, which is quite promising considering CoFe2O4 as an environmentally friendly alternative to the hazardous rare-earth-based permanent magnets. Our CoF2O4 NP ensemble delivers both intriguing low-temperature magnetic properties having academic and technological interests and worthwhile room-temperature features that have direct translational relevance.

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Section: Resultsmentioning

confidence: 55%

Spin Disorder and Particle Size Effects in Cobalt Ferrite Nanoparticles with Unidirectional Anisotropy and Permanent Magnet-like Characteristics

2020

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“…These findings corroborate that the e – filling step profoundly influences the electronic structure and magnetism. To examine the size effect on the modulation of the net moment, we compared our results with bulk materials. , In bulk Fe 3 O 4 , the magnetic saturation ( M S ) value at 300 K is ∼92 Am 2 /kg, and in bulk CoFe 2 O 4 , M S is ∼88 Am 2 /kg . We find that the M S values of nanoscale systems (see Figure g,h) are smaller than that of the bulk because the superexchange interactions are affected by the oxygen vacancies.…”

Section: Results and Discussionmentioning

confidence: 95%

Intervening Oxygen Enabled Magnetic Moment Modulation in Spinel Nanostructures

et al. 2021

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Oxygen vacancies and lattice oxygen on the surface of nanoparticles play crucial roles in the magnetism of transition metal oxides. A fundamental understanding of the interactions between the 2p orbitals of oxygen anions and the 3d orbitals of metal cations is of immense interest for applications due to specific electronic, magnetic, and chemical properties. The spinel nanostructures Co 3 O 4 , Fe 3 O 4 , and CoFe 2 O 4 present a unique model to alter coordination and bonding due to d electrons and oxygen 2p states. We performed complementary experimental techniques and corresponding model calculations to show that the overall net magnetism differs significantly between the O 2 -rich and -deficient environments. It was found that in monometallic spinel oxides (e.g., Co 3 O 4 and Fe 3 O 4 ), the changes in the spin moment are relatively small (∼0.08 μ B per formula unit) compared to those in the bimetallic spinel oxide CoFe 2 O 4 (∼0.40 μ B per formula unit). Our study illustrates that the O 2 -rich/deficient conditions alter the exchange of O h sites and adjust the metal ion moments so as to impact the overall magnetism.

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“…In recent years, magnetic materials with nanostructures have been widely studied and used in many fields. In particular, CoFe 2 O 4 nanoparticles (NPs) have attracted special attention in the fields of supercapacitors, electrocatalysts, magnetic recording materials, and electromagnetic wave absorption owing to their outstanding chemical and physical stability, biocompatibility, and high saturation magnetization …”

Section: Introductionmentioning

confidence: 99%

Distinctive Sandwich-Type Composite Film and Deuterogenic Three-Dimensional Triwall Tubes Affording Concurrent Aeolotropic Conduction, Magnetism, and Up-/Down-Conversion Luminescence

et al. 2022

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Compared to single functional materials, multifunctional materials with electrical conduction, magnetism, and luminescence are more attractive and promising, so it has become an important subject. A distinctive sandwich-type composite film (STCF) with dual-color up- and down-conversion luminescence, magnetism, and aeolotropic conduction is prepared by layer-by-layer electrospinning technology. Macroscopically, STCF is assembled by three tightly bonded layers, including a [polypyrrole (PPy)/poly(methyl methacrylate) (PMMA)]//[NaYF 4 :Yb 3+ , Er 3+ /PMMA] Janus nanobelt array layer as the first layer, a CoFe 2 O 4 /polyacrylonitrile (PAN) nanofiber nonarray layer as the second layer, and a Na 2 GeF 6 :Mn 4+ /polyvinylpyrrolidone (PVP) nanofiber nonarray layer as the third layer. This unique macropartition effectually confines conductive aeolotropy, magnetism, and luminescence in different layers. Microscopically, a Janus nanobelt is used as a construction unit to restrict the luminescent and conductive materials to their microregions, thus achieving highly conductive aeolotropy and green luminescence. The high integration of the micro-subarea and macro-subarea in the STCF can efficaciously avoid the mutual disadvantageous effects among different materials to obtain splendid polyfunctional performance. The conductive anisotropy and magnetism of the STCF can be adjusted by changing the contents of PPy and CoFe 2 O 4 . When the PPy content reaches 70%, the conductance ratio in the conductive direction to insulative direction is 10 8 . The 2D STCF can be crimped by four different methods, and the 3D TWTs have the same excellent polyfunctional performances as 2D STCF. This unique design idea and construction technology can be applied to the preparation of other multifunctional materials to avoid harmful interference among various functions.

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A combined experimental and theoretical study of the magnetic properties of bulk CoFe2O4

Cited by 35 publications

References 27 publications

Spin Disorder and Particle Size Effects in Cobalt Ferrite Nanoparticles with Unidirectional Anisotropy and Permanent Magnet-like Characteristics

Spin Disorder and Particle Size Effects in Cobalt Ferrite Nanoparticles with Unidirectional Anisotropy and Permanent Magnet-like Characteristics

Intervening Oxygen Enabled Magnetic Moment Modulation in Spinel Nanostructures

Distinctive Sandwich-Type Composite Film and Deuterogenic Three-Dimensional Triwall Tubes Affording Concurrent Aeolotropic Conduction, Magnetism, and Up-/Down-Conversion Luminescence

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