Synthesis and Magnetic Properties of MnBi(LTP) Magnets With High-Energy Product

Moon, Ki Woong; Jeon, Kwang-Won; Kang, Min Kyu; Kang, Minkyu; Byun, Yangwoo; Kim, Jin Bae; Kim, Jongryoul

doi:10.1109/tmag.2014.2329555

Cited by 22 publications

(4 citation statements)

References 13 publications

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“…MnBi intermetallic compounds have shown different magnetic characteristics than other magnetic material. The theoretical maximum energy product of MnBi is found to be 127 kJ /m 3 [62] and is also found to have coercivity suitable for VFMs. In addition, MnBi positive temperature coefficient of coercive force is beneficial for VFM designs to operate in high-temperature environments.…”

Section: B Rare-earth Free Permanent Magnetic Materials Such As Mnbimentioning

confidence: 92%

“…Manufacturing techniques such as melt spinning, gas-aggregation-type cluster-deposition, and thin-film processing methods produce nanostructured rare-earth-free materials that may exhibit LCF properties. Some investigations on nanostructured rare-earth-free magnetic material are based on Co-rich transition-metal alloys (HfCo 7 and Zr 2 Co 11 ) [61], [63], Manganese based compounds [62], [64], cobalt-ferrite nanoparticles [65], and FePt-based nanocomposites [66]. However, the high cost of Pt and Hf elements is a prohibitive factor for mass production of certain nanostructured rare-earth-free permanent magnetic material and require further research and development.…”

Section: Development Of Nanostructured Magnetic Materialsmentioning

confidence: 99%

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A Review on Variable Flux Machine Technology: Topologies, Control Strategies and Magnetic Materials

2019

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Modern applications demand challenging operation requirements from electrical machines. Variable-flux machine (VFM) concepts are found to offer new opportunities for improved machine design. This paper reviews the VFM technology. Three topologies, mainly the parallel hybrid VFMs, series hybrid VFMs, and variable-flux flux intensifying type VFMs are discussed in detail. The variable-flux flux Intensifying machines are found to be the state-of-the-art VFM technology available to-date. The paper also reviews the magnetization process in the VFMs and relates this with the B-H curve of the magnetic material. The conventional PM machine mathematical model is adapted to represent the operation of the VFMs. The different operational limitations of the VFMs are explained and the different modes of operation of the VFMs have been reviewed and compared. The magnetization state manipulation techniques are reviewed. The AC magnetization is found to be the more preferable approach to reduce weight and manufacturing complexity of the VFMs. The trapezoidal current pulse based approach is popular in AC magnetization state manipulation, however, new advanced forms of current vector trajectory control techniques offer comparatively better magnetic state manipulation and higher speed capability for remagnetization of the magnets in the VFMs. The paper also reviews the different magnetization state estimation techniques that are useful during control systems development for the VFMs. The magnetic material for the VFM design is reviewed and potential alternative magnetic material that can satisfy the requirements of the VFMs have been identified. Finally, the current status, challenges, and the potential of VFMs technology are discussed in the conclusion of the paper.INDEX TERMS Variable flux machines, wide speed range, permanent magnet machines, field weakening, magnetic material, magnetization, demagnetization, machine design.

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Section: B Rare-earth Free Permanent Magnetic Materials Such As Mnbimentioning

confidence: 92%

Section: Development Of Nanostructured Magnetic Materialsmentioning

confidence: 99%

A Review on Variable Flux Machine Technology: Topologies, Control Strategies and Magnetic Materials

2019

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“…Concerning strontium ferrites, commercial magnets with BH max of 4 MGOe, and even 4.5 MGOe have been commonly offered. The BHmax reported for MnBi until now have been very disappointing, a 6.7 MGOe was reported in very strict laboratorial conditions [25], and 7.8 MGOe for a laboratory sintered material [26]. Liu et al [26] emphasize that MnBi is very sensitive to oxidation and is unstable above 473 K, making very difficult the processing.…”

Section: Comparison Of Hexagonal Ferrites With Other Magnetsmentioning

confidence: 99%

High Technology Applications of Barium and Strontium Ferrite Magnets

Campos

Rodrigues

2016

MSF

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Ceramic magnets as barium ferrite or strontium ferrite have many applications in high technology. One of the reasons is the low cost when compared to competitor materials, as Alnico, MnBi, MnAl or NdFeB. In this study, the advantages and disadvantages of Ba and Sr ferrite magnets are discussed. One clear advantage is that ferrites are already oxides, and do not present the corrosion problems typical of NdFeB and other metallic alloys. As ferrites are oxides, the processing is much easier and cheaper. For example sintering can be done at air, and milling under wet condition. One of the main conclusions is the excellent ratio cost/benefit of ferrites, giving advantage in many applications. Special attention is given for application of ferrites in high efficiency motors.

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“…The NCs rather get degraded lacking to design a large (BH) max beyond 7.3 MGOe or so [39,40]. Annealing in fields is realized a simple recipe to devise α-MnBi aligned in a high grade nanotexture [16,[39][40][41][42][43][44][45]. Though tuning field aligned FM NCs at anneals was proposed a long ago by Boothby et al in 1958 [46], yet the field annealed MnBi lacks either a high H c [41,45], or a duly large α-MnBi yield [16,42].…”

Section: Introductionmentioning

confidence: 99%

A core–shell magnet Mn₇₀Bi₃₀ grown at seeds in magnetic fields and its impacts on its spin-dynamics, Curie point and other tailored properties

2023

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The MnBi alloys is a model series of rare-earth free magnets for surge of technologies of small parts of automobiles, power generators, medical tools, memory systems, and many others. The magnetics stem primarily at unpaired Mn-3d5 spins (a 4.23 B moment) align parallel via an orbital moment 0.27 B of Bi-5d106s2p3 in a crystal lattice. Thus, using a surplus Mn (over Bi) in a Mn70Bi30 type alloy designs a spin-rich system of duly tailored properties useful for magnetics and other devices. In this view, we report here a strategy of a refined alloy powder Mn70Bi30 can grow into small crystals of hexagonal (h) plates at seeds as annealed in magnetic fields (in H2 gas). So, small h-plates (30 to 50 nm widths) are grown up at (002) facets, wherein the edges are turned down in a spiral ( 2.1 nm thicknesses) in a core-shell structure. The results are described with X-ray diffraction, lattice images and magnetic properties of a powder Mn70Bi30 (milled in glycine) is annealed at 573 K for different time periods, so to the Mn/Bi order at the permeable facets (seeds). Duly annealed samples exhibit an enhanced magnetization, Ms  70.8 emu/g, with duly promoted coercivity Hc  10.810 kOe (15.910 kOe at 350 K), energy–product 14.8 MGOe, and the crystal-field-anisotropy, K1  7.6x107 erg/cm3, reported at room temperature. Otherwise, Ms should decline at any surplus 3d5-Mn spins order antiparallel at the antisites. Enhanced Curie point 658.1 K (628 K at Mn50Bi50 alloy) anticipates that a surplus Mn does favor the Mn-Bi exchange interactions. Proposed spin models well describe the spin-dynamics and lattice relaxations (on anneals) over the lattice volume (with twins) and spin clusters.

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Synthesis and Magnetic Properties of MnBi(LTP) Magnets With High-Energy Product

Cited by 22 publications

References 13 publications

A Review on Variable Flux Machine Technology: Topologies, Control Strategies and Magnetic Materials

A Review on Variable Flux Machine Technology: Topologies, Control Strategies and Magnetic Materials

High Technology Applications of Barium and Strontium Ferrite Magnets

A core–shell magnet Mn₇₀Bi₃₀ grown at seeds in magnetic fields and its impacts on its spin-dynamics, Curie point and other tailored properties

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Synthesis and Magnetic Properties of MnBi(LTP) Magnets With High-Energy Product

Cited by 22 publications

References 13 publications

A Review on Variable Flux Machine Technology: Topologies, Control Strategies and Magnetic Materials

A Review on Variable Flux Machine Technology: Topologies, Control Strategies and Magnetic Materials

High Technology Applications of Barium and Strontium Ferrite Magnets

A core–shell magnet Mn70Bi30 grown at seeds in magnetic fields and its impacts on its spin-dynamics, Curie point and other tailored properties

Contact Info

Product

Resources

About

A core–shell magnet Mn₇₀Bi₃₀ grown at seeds in magnetic fields and its impacts on its spin-dynamics, Curie point and other tailored properties