Production of Fe nanoparticles from γ-Fe<sub>2</sub>O<sub>3</sub> by high-pressure hydrogen reduction

Dirba, Imants; Schwöbel, C. A.; Zintler, Alexander; Komissinskiy, Philipp; Molina‐Luna, Leopoldo; Gutfleisch, Oliver

doi:10.1039/d0na00635a

Cited by 13 publications

(10 citation statements)

References 35 publications

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“…In this regard, a bigger effort may be put forth to develop an easy and scalable way to synthesize oxide precursors with high-quality nanocrystallites to preserve the nanoscale features before undergoing reduction [27,28]. Moreover, to make the process more efficient, different strategies have been proposed, such as the use of hydrogen at high pressure [29] or the application of a magnetic field during the reaction [30,31]. The latter was demonstrated to be highly efficient in terms of reduction of the processing temperature.…”

Section: Introductionmentioning

confidence: 99%

High-Moment FeCo Magnetic Nanoparticles Obtained by Topochemical H2 Reduction of Co-Ferrites

et al. 2022

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Cobalt ferrite nanoparticles of different stoichiometries synthesized by a sol–gel autocombustion method were used as a starting material to obtain high-moment Fe50Co50 and Fe66Co34 metal nanoparticles by topochemical hydrogen reduction. Structural and magnetic investigations confirmed the formation of FeCo nanoparticles with crystallite sizes of about 30 nm and magnetization at 0.5 T of ~265 Am2/kg (0 K), which was larger than the expected bulk value, likely because of the incorporation in the body-centered cubic (bcc) FeCo structure of the residual C atoms present on the surface of the oxide particles. Temperature-dependent magnetization measurements in the H2 atmosphere were also performed to investigate in detail the reduction mechanism and the effect of an external magnetic field on the process efficiency.

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Section: Introductionmentioning

confidence: 99%

High-Moment FeCo Magnetic Nanoparticles Obtained by Topochemical H2 Reduction of Co-Ferrites

et al. 2022

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“…High phase-purity α ′′ -Fe 16 N 2 nanoparticles used in this study have been produced via a novel two-step route established by Dirba et al [23]. First, commercial γ-Fe 2 O 3 nanoparticles with an average particle size of 20-40 nm were reduced to α-Fe in high-pressure hydrogen [68]. In the second step, the resulting α-Fe nanoparticles were nitrogenated in an ammonia flow to produce the iron nitride.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of Fe-nitrides, -borides and -carbides for enhanced magnetic fluid hyperthermia with experimental study of α″-Fe₁₆N₂ and ϵ-Fe₃N nanoparticles

Dirba

Chandra

Ablets

et al. 2022

J. Phys. D: Appl. Phys.

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In this work, we investigate alternative materials systems that, based on their intrinsic magnetic properties, have the potential to deliver enhanced heating power in magnetic fluid hyperthermia. The focus lies on systems with high magnetization phases, namely iron-nitrogen (Fe-N), iron-boron (Fe-B) and iron-carbon (Fe-C) compounds, and their performance in comparison to the conventionally used iron oxides, γ-Fe2O3, Fe3O4 and non-stoichiometric mixtures thereof. The heating power as a function of the applied alternating magnetic field frequency is calculated and the peak particle size with the maximum specific loss power (SLP) for each material is identified. It is found that lower anisotropy results in larger optimum particle size and more tolerance for polydispersity. The effect of nanoparticle saturation magnetization and anisotropy is simulated, and the results show that in order to maximize SLP, a material with high magnetization but low anisotropy provides the best combination. These findings are juxtaposed with experimental results of a comparative study of iron nitrides, namely α″-Fe16N2 and ε-Fe3N nanoparticles, and model nanoparticles of iron oxides. The former ones are studied as heating agents for magnetic fluid hyperthermia for the first time.

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“…Recent works have shown that nanocomposite magnets offer a possibility to engineer magnetic properties by using a mixture of hard and soft phases. , Therefore, in addition to improved densification, enhancing the maximum energy product (BH) max of ferrite magnets by increasing the saturation magnetization M s via the exchange-spring-magnet principle has been tried and, if successful, would have great technological and economical importance. For example, bulk composite magnets by using Al-doped Sr-hexaferrite SrAl 2 Fe 10 O 19 as the hard phase and environmentally friendly iron nitride α″-Fe 16 N 2 nanoparticles obtained by hydrogen reduction of Fe 2 O 3 as the soft (semihard) phase were studied demonstrating that indeed adding α″-Fe 16 N 2 leads to increased M s and a slight increase in M r …”

Section: Introductionmentioning

confidence: 99%

Life Cycle Assessment of Rare Earth Elements-Free Permanent Magnet Alternatives: Sintered Ferrite and Mn–Al–C

Amato,

Becci,

Bollero

et al. 2023

ACS Sustainable Chem. Eng.

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Permanent magnets are fundamental constituents in key sectors such as energy and transport, but also robotics, automatization, medicine, etc. High-performance magnets are based on rare earth elements (RE), included in the European list of critical raw materials list. The volatility of their market increased the research over the past decade to develop RE-free magnets to fill the large performance/cost gap existing between ferrites and RE-based magnets. The improvement of hard ferrites and Mn–Al–C permanent magnets plays into this important technological role in the near future. The possible substitution advantage was widely discussed in the literature considering both magnetic properties and economic aspects. To evaluate further sustainability aspects, the present paper gives a life cycle assessment quantifying the environmental gain resulting from the production of RE-free magnets based on traditional hexaferrite and Mn–Al–C. The analysis quantified an advantage of both magnets that overcomes the 95% in all the considered impact categories (such as climate change, ozone depletion, human toxicity) compared to RE-based technologies. The benefit also includes the health and safety of working time aspects, proving possible reduction of worker risks by 3–12 times. The results represent the fundamentals for the development of green magnets that are able to significantly contribute to an effective sustainable transition.

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Production of Fe nanoparticles from γ-Fe₂O₃ by high-pressure hydrogen reduction

Abstract: In this work, the reduction of iron oxide γ-Fe2O3 nanoparticles by hydrogen at high pressures is studied. Increasing the hydrogen pressure enables reduction of γ-Fe2O3 to α-Fe at significantly lower...

Cited by 13 publications

References 35 publications

High-Moment FeCo Magnetic Nanoparticles Obtained by Topochemical H2 Reduction of Co-Ferrites

High-Moment FeCo Magnetic Nanoparticles Obtained by Topochemical H2 Reduction of Co-Ferrites

Evaluation of Fe-nitrides, -borides and -carbides for enhanced magnetic fluid hyperthermia with experimental study of α″-Fe₁₆N₂ and ϵ-Fe₃N nanoparticles

Life Cycle Assessment of Rare Earth Elements-Free Permanent Magnet Alternatives: Sintered Ferrite and Mn–Al–C

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Production of Fe nanoparticles from γ-Fe2O3 by high-pressure hydrogen reduction

Abstract: In this work, the reduction of iron oxide γ-Fe2O3 nanoparticles by hydrogen at high pressures is studied. Increasing the hydrogen pressure enables reduction of γ-Fe2O3 to α-Fe at significantly lower...

Cited by 13 publications

References 35 publications

High-Moment FeCo Magnetic Nanoparticles Obtained by Topochemical H2 Reduction of Co-Ferrites

High-Moment FeCo Magnetic Nanoparticles Obtained by Topochemical H2 Reduction of Co-Ferrites

Evaluation of Fe-nitrides, -borides and -carbides for enhanced magnetic fluid hyperthermia with experimental study of α″-Fe16N2 and ϵ-Fe3N nanoparticles

Life Cycle Assessment of Rare Earth Elements-Free Permanent Magnet Alternatives: Sintered Ferrite and Mn–Al–C

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Product

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Production of Fe nanoparticles from γ-Fe₂O₃ by high-pressure hydrogen reduction

Evaluation of Fe-nitrides, -borides and -carbides for enhanced magnetic fluid hyperthermia with experimental study of α″-Fe₁₆N₂ and ϵ-Fe₃N nanoparticles