Rare-Earth-Free Permanent Magnets: The Past and Future

Mohapatra, Jeotikanta; Liu, Jia Ping

doi:10.1016/bs.hmm.2018.08.001

Cited by 53 publications

(52 citation statements)

References 212 publications

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“…Ce is regarded as an RE metal but is still relatively abundant, making up 66 ppm of the earth's crust, comparing to 41 ppm for Nd [32]. Materials that could be possible candidates for filling the gap are discussed in Mohapatra [33] and Coey [22]. Among the candidates are FePt, FeNi, Co-carbide, Fe-nitride, ZrCo 11 , HfCo 7 , Y 2 Fe 14 B and YCo 5 , along with Mn-based compounds such as MnBi, Mn 2 Ga and MnAl.…”

Section: Materials That Could Be Used In Future Electrical Machinesmentioning

confidence: 99%

“…The MnAl τ-phase [23,33,34] that was first reported by Kono [35] and Koch [36] in the late 1950s has been suggested as a potential replacement for ferrites as a PM [37]. Mohapatra, on the other hand, claims that in order to compete with ferrite magnets and spread their field of application, improved PM attributes are still required [33]. In the review presented by Patel [38], it is concluded that Mn-based magnetic alloys (MnBi, MnAl and MnGa) have shown potential as alternatives for the replacement of RE magnetic materials, even though a lot of work and effort is still required.…”

Section: Materials That Could Be Used In Future Electrical Machinesmentioning

confidence: 99%

“…In the composition range of 50-60 at. % Mn, the metastable τ-phase which is strongly ferromagnetic can be formed [33]. No other phases in the Mn-Al system are known to be ferromagnetic.…”

Section: Materials That Could Be Used In Future Electrical Machinesmentioning

confidence: 99%

“…No other phases in the Mn-Al system are known to be ferromagnetic. With the intrinsic properties of saturation magnetization (M s ) of 0.62 T (493 kA/m) [33], a Curie temperature (T c ) of 285-380 • C [33,39], and a magnetocrystalline anisotropy constant (K 1 ) of 1.7 MJ/m3 [23], τ-phase MnAl has the potential for becoming a PM with high coercivity and a high energy product at elevated temperatures. Alloying with carbon has shown positive effects on stabilizing the τ-phase [12,23,40,41] and it has been reported that the material was heated and kept at 200 • C for several weeks without significant effects on the magnetic properties [42].…”

Section: Materials That Could Be Used In Future Electrical Machinesmentioning

confidence: 99%

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An Overview of MnAl Permanent Magnets with a Study on Their Potential in Electrical Machines

et al. 2020

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In this paper, hard magnetic materials for future use in electrical machines are discussed. Commercialized permanent magnets used today are presented and new magnets are reviewed shortly. Specifically, the magnetic MnAl compound is investigated as a potential material for future generator designs. Experimental results of synthesized MnAl, carbon-doped MnAl and calculated values for MnAl are compared regarding their energy products. The results show that the experimental energy products are far from the theoretically calculated values with ideal conditions due to microstructure-related reasons. The performance of MnAl in a future permanent magnet (PM) generator is investigated with COMSOL, assuming ideal conditions. Simplifications, such as using an ideal hysteresis loop based on measured and calculated saturation magnetization values were done for the COMSOL simulation. The results are compared to those for a ferrite magnet and an NdFeB magnet. For an ideal MnAl hysteresis loop, it would be possible to replace ferrite with MnAl, with a reduced weight compared to ferrite. In conclusion, future work for simulations with assumptions and results closer to reality is suggested.

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Section: Materials That Could Be Used In Future Electrical Machinesmentioning

confidence: 99%

Section: Materials That Could Be Used In Future Electrical Machinesmentioning

confidence: 99%

“…In the composition range of 50-60 at. % Mn, the metastable τ-phase which is strongly ferromagnetic can be formed [33]. No other phases in the Mn-Al system are known to be ferromagnetic.…”

Section: Materials That Could Be Used In Future Electrical Machinesmentioning

confidence: 99%

Section: Materials That Could Be Used In Future Electrical Machinesmentioning

confidence: 99%

See 2 more Smart Citations

An Overview of MnAl Permanent Magnets with a Study on Their Potential in Electrical Machines

et al. 2020

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“…11 When alloyed with other elements, the magnetic and mechanic properties can be tuned accordingly. 12,13 AlNiCo-type magnetic systems attracted attention for their temperature stability and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Crystal Structure, Magnetism, and Electronic Properties of a Rare-Earth-Free Ferromagnet: MnPt₅As

Gui

Xie

2020

Chem. Mater.

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The design and synthesis of targeted functional materials have been a long-term goal for material scientists. Although a universal design strategy is difficult to generate for all types of materials, however, it is still helpful for a typical family of materials to have such design rules.Herein, we incorporated several significant chemical and physical factors regarding magnetism, such as structure type, atom distance, spin-orbit coupling, and successfully synthesized a new rareearth-free ferromagnet, MnPt5As, for the first time. MnPt5As can be prepared by using hightemperature pellet methods. According to X-ray diffraction results, MnPt5As crystallizes in a tetragonal unit cell with the space group P4/mmm (Pearson symbol tP7). Magnetic measurements on MnPt5As confirm ferromagnetism in this phase with a Curie temperature of 301 K and a saturated moment of 3.5 B per formula. Evaluation by applying the Stoner Criterion also indicates that MnPt5As is susceptible to ferromagnetism. Electronic structure calculations using the WIEN2k program with local spin density approximation imply that the spontaneous magnetization of this phase arises primarily from the hybridization of d orbitals on both Mn and Pt atoms. The theoretical assessments are consistent with the experimental results. Moreover, the spin-orbit coupling effects heavily influence on magnetic moments in MnPt5As. MnPt5As is the first highperformance magnetic material in this structure type. The discovery of MnPt5As offers a platform to study the interplay between magnetism and structure.

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Nanomaterial Patterning in 3D Printing

et al. 2020

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The synergistic integration of nanomaterials with 3D printing technologies can enable the creation of architecture and devices with an unprecedented level of functional integration. In particular, a multiscale 3D printing approach can seamlessly interweave nanomaterials with diverse classes of materials to impart, program, or modulate a wide range of functional properties in an otherwise passive 3D printed object. However, achieving such multiscale integration is challenging as it requires the ability to pattern, organize, or assemble nanomaterials in a 3D printing process. This review highlights the latest advances in the integration of nanomaterials with 3D printing, achieved by leveraging mechanical, electrical, magnetic, optical, or thermal phenomena. Ultimately, it is envisioned that such approaches can enable the creation of multifunctional constructs and devices that cannot be fabricated with conventional manufacturing approaches.

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Rare-Earth-Free Permanent Magnets: The Past and Future

Cited by 53 publications

References 212 publications

An Overview of MnAl Permanent Magnets with a Study on Their Potential in Electrical Machines

An Overview of MnAl Permanent Magnets with a Study on Their Potential in Electrical Machines

Crystal Structure, Magnetism, and Electronic Properties of a Rare-Earth-Free Ferromagnet: MnPt₅As

Nanomaterial Patterning in 3D Printing

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Rare-Earth-Free Permanent Magnets: The Past and Future

Cited by 53 publications

References 212 publications

An Overview of MnAl Permanent Magnets with a Study on Their Potential in Electrical Machines

An Overview of MnAl Permanent Magnets with a Study on Their Potential in Electrical Machines

Crystal Structure, Magnetism, and Electronic Properties of a Rare-Earth-Free Ferromagnet: MnPt5As

Nanomaterial Patterning in 3D Printing

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Product

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Crystal Structure, Magnetism, and Electronic Properties of a Rare-Earth-Free Ferromagnet: MnPt₅As