Morphology and magnetic properties of α”-Fe&lt;sub&gt;16&lt;/sub&gt;N&lt;sub&gt;2&lt;/sub&gt; nanoparticles synthesized from iron hydroxide and iron oxides

Tobise, M.; Ogawa, Tomoyuki; Saito, Shin

doi:10.3379/msjmag.1704r003

Cited by 15 publications

(8 citation statements)

References 14 publications

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“…Many such materials show ferromagnetism when ordered, while being nonmagnetic in disordered state; this property is explored in terms of application to bit patterned media, a new generation of ultra-high density recording media. 5 Regarding Fe 16 N 2 , its giant magnetic moment was reported in 1970s, 6 and then many experiments were carried out; 7,8 recently, formation of single-phase particles was reported, 9 and the compound has been commercialized as a semi-hard material with high M s . Semi-hard properties of this material can be attributed to changes in the crystal structure and band structure due to nitridation of iron.…”

Section: Progress In Rare-earth Permanent Magnetsmentioning

confidence: 99%

Challenges toward development of rear‐earth free FeCo based permanent magnet

Hasegawa

2021

Elect Comm in Japan

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Among the various permanent magnets reported to date, FeNdB exhibits the highest magnetic performance, but reducing the use of the rare‐earth elements is necessary to avoid exhaustion of rare‐earth elements. The key to improve the performance of permanent magnets is to increase magnetization and coercivity. FeCo has a very large magnetization, but has a very small coercivity caused by the extremely small magnetic anisotropy due to the cubic crystal structure, so that FeCo has long been unsuitable for permanent magnets. However, recent reports have revealed that the transformation of the crystal structure from cubic to tetragonal causes large magnetic anisotropy. In 2017, the author reported that a large coercivity can be obtained by fabricating tetragonal FeCo nanodots. This article reviews recent progress of rear‐earth free permanent magnets especially for the tetragonal FeCo based alloys.

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Section: Progress In Rare-earth Permanent Magnetsmentioning

confidence: 99%

Challenges toward development of rear‐earth free FeCo based permanent magnet

Hasegawa

2021

Elect Comm in Japan

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“…The as-leached sample showed bcc-Fe peaks with weak oxide peaks. For samples with hydrogen reduction at 500°C, a tiny 202 Fe 16 Table 2. Oxide peaks for as-leached sample were assigned to Fe 2 O 3 with space group P4 1 2 1 2.…”

Section: ¡¤¤-Fe 16 Nmentioning

confidence: 99%

“…Sample 1, consisting mostly of Fe, had M s = 226 « 16 A m 2 kg ¹1 , which was close to the M s of bulk Fe (218 A m 2 kg ¹1 ). 16) The somewhat larger M s originated from a large error in sample weight (13 « 1 mg). In contrast, Samples 3, 6, 8, and 9, consisting mostly of Fe 16 N 2 , had smaller M s than Fe even though both ¡AA and ¡A phases had larger M s than Fe.…”

Section: ¡¤¤-Fe 16 Nmentioning

confidence: 99%

“…15) The material ¡AA-Fe 16 N 2 is a metastable phase. Owing to the considerable efforts of many researchers, methods for obtaining highquality specimens have been established 16) for thin films using reactive sputtering 17) and for nanoparticles by hydrogen reduction of iron oxides followed by ammonia nitriding. 18) Here, we report trials to obtain L1 0 -FeNi and ¡AA-Fe 16 N 2 through the method of leaching (dealloying), which is the selective dissolution of less noble metals from a mother alloy using acid or alkaline solutions.…”

Section: Introductionmentioning

confidence: 99%

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FeNi and Fe<sub>16</sub>N<sub>2</sub> Magnets Prepared Using Leaching

et al. 2019

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L1 0 -type FeNi alloys and ¡AA-Fe 16 N 2 are candidates for permanent magnets without precious metals, but they are difficult to prepare because atomic diffusion is extremely slow below the orderdisorder transition temperature of L1 0 -FeNi (320°C) and because ¡AA-Fe 16 N 2 is a metastable phase. Here, we report trials for preparing them using leaching, which is a method to obtain porous metals with a high surface area. We used such chemically active porous alloys as precursors for preparing L1 0 -FeNi using the driving force of atomic diffusion and for preparing ¡AA-Fe 16 N 2 using high reactivity with ammonia. No proofs for obtaining the L1 0 -FeNi phase were observed, likely due to an Al impurity of 10 mol% and/or too small of a grain size. An Fe 16 N 2 with ¡AA phase was obtained. Although the saturation magnetization was smaller than that of Fe, a large coercivity (up to 121 kA m ¹1 ) was obtained.

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“…However, the production of such foils is costly, and bulk magnet synthesis is not feasible. Current research on the subject focuses on the successful production of working Fe 16 N 2 [ 18,20–27 ] permanent magnets. The main drawback to the production of bulk Fe 16 N 2 permanent magnets is that the α″‐Fe 16 N 2 body centered tetragonal (BCT) phase ( Figure ) responsible for the GSM is unstable above 212 °C; [ 7 ] therefore, the usual permanent magnet production routes, involving treatment at high temperature, [ 1 ] cannot be used.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Characterization of Fe₁₆N₂Micro‐Flake Powders and Their Extrusion‐Based 3D Printing into Permanent Magnet Form

et al. 2020

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Fe16N2 is a compound with giant saturation magnetization approaching or exceeding that of rare‐earth‐based permanent magnets. The abundance of its elements and low‐cost synthesis of this compound has made it highly attractive to replace rare‐earth‐based permanent magnets that are becoming ever more expensive to utilize in applications. Herein, its synthesis from Fe flakes by surfactant‐assisted high energy ball milling is demonstrated. The synthesized Fe flakes are then reduced under forming gas (Ar/H2), followed by nitridation at low temperatures under ammonia (NH3) gas. The formation of Fe16N2 phase exceeding 50% by volumetric fraction is observed and confirmed by X‐ray diffraction and Mössbauer analysis. Following the Fe16N2 flake synthesis, extrusion‐based 3D printing is used to check the feasibility of incorporation of the flakes into functional polymer matrix composites. For this purpose, an ink of intermixed synthesized powder with photoresist SU8 is used. Using the prescribed method, a prototype Fe16N2 permanent magnet composite is successfully produced using an additive manufacturing approach. Such efficient production of Fe16N2 powders via routes already applicable to magnet production and the consolidation of the powders with 3D printing are expected to open up new possibilities for next‐generation permanent magnet applications.

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Morphology and magnetic properties of α”-Fe<sub>16</sub>N<sub>2</sub> nanoparticles synthesized from iron hydroxide and iron oxides

Cited by 15 publications

References 14 publications

Challenges toward development of rear‐earth free FeCo based permanent magnet

Challenges toward development of rear‐earth free FeCo based permanent magnet

FeNi and Fe<sub>16</sub>N<sub>2</sub> Magnets Prepared Using Leaching

Fabrication and Characterization of Fe₁₆N₂Micro‐Flake Powders and Their Extrusion‐Based 3D Printing into Permanent Magnet Form

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Morphology and magnetic properties of α”-Fe<sub>16</sub>N<sub>2</sub> nanoparticles synthesized from iron hydroxide and iron oxides

Cited by 15 publications

References 14 publications

Challenges toward development of rear‐earth free FeCo based permanent magnet

Challenges toward development of rear‐earth free FeCo based permanent magnet

FeNi and Fe<sub>16</sub>N<sub>2</sub> Magnets Prepared Using Leaching

Fabrication and Characterization of Fe16N2Micro‐Flake Powders and Their Extrusion‐Based 3D Printing into Permanent Magnet Form

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Product

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Fabrication and Characterization of Fe₁₆N₂Micro‐Flake Powders and Their Extrusion‐Based 3D Printing into Permanent Magnet Form