Magnetic properties and structural analysis on spinel MnFe2O4 nanoparticles prepared via non‐aqueous microwave synthesis

Simon, Christopher; Blößer, André; Eckardt, Mirco; Kurz, Haymo; Weber, Birgit; Zobel, Mirijam; Marschall, Roland

doi:10.1002/zaac.202100190

Cited by 12 publications

(6 citation statements)

References 92 publications

(183 reference statements)

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“…A generally good agreement with literature is observed for binary ferrites. [51,34,70,71,54,[75][76][77] On the one hand, an increasing crystallinity has an effect, as especially apparent in the spectra of NiFe 2 O 4 . On the other hand, cation redistribution during calcination might affect the relative intensity of the CT-bands.…”

Section: Supporting Information)mentioning

confidence: 99%

Medium‐ and High‐Entropy Spinel Ferrite Nanoparticles via Low‐Temperature Synthesis for the Oxygen Evolution Reaction

Zander,

Wölfel,

Weiss

et al. 2023

Adv Funct Materials

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High‐entropy oxides are a material class that is currently receiving rapidly increasing attention due to the large variety in composition and the adjustable properties. Cooperative effects between different metal cations in the crystal structure in addition to entropic phase stabilization have proven beneficial for electrocatalytic applications. Most synthesis methods, however, require high synthesis temperatures and long times, and additionally only yield selected samples in good phase‐purity. Furthermore, toxic or scarce elements are often present in large amounts. Herein, a non‐aqueous microwave‐assisted solvothermal synthesis is presented as a fast and low‐temperature alternative for the fabrication of a wide range of earth‐abundant ferrites (AFe2O4). Directly crystalline, phase‐pure spinel ferrites of various compositions ranging from one to seven different A‐ions are successfully obtained after only 30 min at 225 °C. A detailed characterization of their properties in relation to their composition is performed, and they are also employed for the alkaline oxygen evolution reaction. A partial replacement of Fe by Co moreover shows the high versatility of the synthesis that also allows for the simultaneous variation of the B‐ion.

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Section: Supporting Information)mentioning

confidence: 99%

Medium‐ and High‐Entropy Spinel Ferrite Nanoparticles via Low‐Temperature Synthesis for the Oxygen Evolution Reaction

Zander,

Wölfel,

Weiss

et al. 2023

Adv Funct Materials

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“…[ 45 ] Similar approaches with the solvent acting as a stabilizing agent have been shown for other ferrites in our group as well. [ 37–39 ] For copper ferrite, a microwave synthesis in organic solvents, however, results in a reduction of Cu 2+ and the formation of Cu 0 by‐phases. [ 41 ]…”

Section: Introductionmentioning

confidence: 99%

“…[36] As an alternative, microwave-assisted syntheses allow for the preparation of spinel ferrite nanoparticles. [37][38][39] Due to fast homogeneous heating, reaction times can often be significantly reduced compared to conventional hydrothermal synthesis and the size distribution can be narrowed. [37,38,[40][41][42] Phuruangrat et al have shown in first experiments that microwave-assisted hydrothermal synthesis is feasible for the direct synthesis of crystalline CuFe 2 O 4 in its cubic form.…”

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confidence: 99%

“…[45] Similar approaches with the solvent acting as a stabilizing agent have been shown for other ferrites in our group as well. [37][38][39] For copper ferrite, a microwave synthesis in organic solvents, however, results in a reduction of Cu 2þ and the formation of Cu 0 by-phases. [41] We herein present a fast, reproducible microwave-assisted synthesis of cubic CuFe 2 O 4 nanoparticles in water, with additional ethylene glycol acting as stabilizing agent in the reaction solution, improving phase purity and homogeneity by preventing the precipitation of hydroxides.…”

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confidence: 99%

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Fast and Facile Microwave Synthesis of Cubic CuFe₂O₄ Nanoparticles for Electrochemical CO₂ Reduction

Zander

Weiß

Marschall

2023

Adv Energy and Sustain Res

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Nanoparticles of cubic CuFe2O4 are obtained in a fast microwave‐assisted hydrothermal synthesis. By adjusting the pH value and solvent ratio (ethylene glycol to water), phase purity and high crystallinity is achieved at very short reaction times of 1 min, or low temperatures of 120 °C, without the need for subsequent heat treatment steps. The influence of the synthesis time or temperature on material properties and performance in electrochemical CO2 reduction to CO are investigated. While particle size and crystallinity are not changed significantly with longer synthesis times at 175 °C, prolonged heating results in a decrease of the degree of inversion, which leads to a decrease in the CO2 reduction ability. The best performance is observed for CuFe2O4 with an intermediate degree of inversion of approx. 0.75, together with the largest crystallite size and micro‐strain, as revealed by Rietveld refinement. For CuFe2O4 synthesized under these conditions, a CO evolution rate of 0.2 μmol h−1 g−1 is obtained at a Faradaic efficiency of 20%. The CO to H2 ratio is 1:3, which makes it a promising candidate for a sustainable production of syngas.

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“…x Fe 3+ 2−x ], where the parentheses show the tetrahedral site occupancy and square brackets show the octahedral site occupancy and x is the degree of inversion (5 µ B when x=0, and 3µ B when x=1). [165,166] The magnetic properties of manganese ferrite are dependent on the occupancy and exchange of cations in the two sites. The A-B interaction is the strongest super-exchange interaction, followed by the B-B, and then A-A superexchange interaction in spinel ferrites, and the total magnetic moment can be calculated by the magnetic moment of ions and the exchange interactions between them.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Magnetic Nanofibers for Their Potential Applications in Wireless Charging for Energy Efficient EVs

Nawaz¹

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There is a growing demand to find new materials for flux guiding applications in the inductive power transfer systems. The inductive power transfer system (IPT) in electric vehicles has gained importance due to advantages including safety, efficiency, flexibility, and user-friendliness. The potential of IPT systems in dynamic flux transfer on-road requires the flux concentrators to maximize flux transfer at minimum power losses. Ferrite materials are the most commonly used materials in the IPT cores for flux-transfer applications due to their reasonable susceptibility, high resistivity, and semi-conducting nature. Their high resistivity is advantageous to minimize eddy-current losses. However, there are certain drawbacks to their use, for example, they can still result in some eddy-current losses as their resistivity is not high enough, they are very brittle in nature and are difficult to be made in thin sheets or in arbitrary shapes, and they are very heavy that increases the vehicle mass and energy consumption. An ideal material for wireless charging applications should be thin, and flexible that can be made in arbitrary shapes with a reasonable susceptibility and high resistivity for wireless charging applications. This thesis aimed to investigate the preparation of bimetallic Ni1−xFex, semi-conducting MnFe2O4, and Sm3+ doped semi-conducting MnFe2−xSmxO4 nanofibers made by an electrospinning method for their potential applications in wireless charging. Ni1−xFex was selected because the bulk material shows a high permeability which is useful for flux-guiding, but it has a low resistivity. However, the preparation of thin Ni1−xFex nanofiber sheets can result in high resistivities in nanodimensions. The parameter x was studied by varying its value between 0.1-0.5 as Ni1−xFex show high susceptibility at x∼0.2, and high magnetic moment at x∼0.5. The characterizations showed the presence of Ni1−xFex nanoparticles formation within nanofibers for all the samples which can be advantageous to further increasing the resistivity and to reduce eddy-current losses. A bimodal particle size distribution was observed at x∼0.1, that became less bimodal at x∼0.2 and skewed with predominantly small nanoparticles at x∼0.5. Superparamagnetic behaviour was observed at x∼0.5 due to the formation of smaller nanoparticles. There was a systematic increase in the differential susceptibility with increasing x from 6 at x∼0.1 to 18 at x∼0.5. These results were encouraging for potential applications in wireless charging. Semiconducting MnFe2O4 nanofibers were made by electrospinning method because bulk material has high resistivity. The thermal processing of these nanofibers at 700◦C resulted in large polycrystalline nanoparticles whereas, the thermal processing at lower temperature 620◦C resulted in a mixture of small nanoparticles within these nanofibers. The presence of some single crystal nanorods was also seen in both samples. The high field magnetization was largest for the sample processed at higher temperature, i.e., 57% of the total magnetization value at 700◦C as compared to 46% obtained at low temperatures at 620◦C. However, one sample processed at 620◦C showed the complete formation of MnFe2O4 nanorods with the highest saturation magnetization to 76% of the total magnetization. These results are encouraging as the potential of nanorod synthesis can be useful in the flux guiding applications. Electrospun MnFe2−xSmxO4 nanofibers with Sm3+(x) doping were also made to observe the change in the structural and magnetic properties at x=0.06-0.25. The results showed the successful incorporation of Sm3+ in the crystal structure of MnFe2O4 at x≤0.2. Polycrystalline nanoparticles were seen at low fractions of x≤0.1 but more smaller nanoparticles were formed at x=0.2 and x=0.25. Superparamagnetic behaviour was observed at high fractions of x (x=0.2 and x=0.25). The saturation magnetization for x≤0.2 was largest for x=0.06. This study has provided a solid foundation for a more in-depth exploration of magnetic electrospun nanofiber sheets for future applications in wireless charging systems.

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Magnetic properties and structural analysis on spinel MnFe₂O₄ nanoparticles prepared via non‐aqueous microwave synthesis

Cited by 12 publications

References 92 publications

Medium‐ and High‐Entropy Spinel Ferrite Nanoparticles via Low‐Temperature Synthesis for the Oxygen Evolution Reaction

Medium‐ and High‐Entropy Spinel Ferrite Nanoparticles via Low‐Temperature Synthesis for the Oxygen Evolution Reaction

Fast and Facile Microwave Synthesis of Cubic CuFe₂O₄ Nanoparticles for Electrochemical CO₂ Reduction

Synthesis of Magnetic Nanofibers for Their Potential Applications in Wireless Charging for Energy Efficient EVs

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Magnetic properties and structural analysis on spinel MnFe2O4 nanoparticles prepared via non‐aqueous microwave synthesis

Cited by 12 publications

References 92 publications

Medium‐ and High‐Entropy Spinel Ferrite Nanoparticles via Low‐Temperature Synthesis for the Oxygen Evolution Reaction

Medium‐ and High‐Entropy Spinel Ferrite Nanoparticles via Low‐Temperature Synthesis for the Oxygen Evolution Reaction

Fast and Facile Microwave Synthesis of Cubic CuFe2O4 Nanoparticles for Electrochemical CO2 Reduction

Synthesis of Magnetic Nanofibers for Their Potential Applications in Wireless Charging for Energy Efficient EVs

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Product

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Magnetic properties and structural analysis on spinel MnFe₂O₄ nanoparticles prepared via non‐aqueous microwave synthesis

Fast and Facile Microwave Synthesis of Cubic CuFe₂O₄ Nanoparticles for Electrochemical CO₂ Reduction