Permanent magnet materials based on the rare earth-iron-boron tetragonal compounds

Sagawa, M.; Fujimura, S.; Yamamoto, H.; Matsuura, Yutaka; Hiraga, Kenji

doi:10.1109/tmag.1984.1063214

Cited by 748 publications

(210 citation statements)

References 16 publications

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“…The measured and estimated K dimer show an estimated 10 11 -fold decrease across the series. A complete matrix of 54 separations factors, S RE1/RE2 , is provided for the early/late RE combinations, determined by 1 H NMR spectroscopy experiments and inductively coupled plasma optical emission spectroscopy (ICP-OES) data on the separated fractions. We expect that the results disclosed here will aid in the development of improved methods for separating Eu/Y mixtures with potential applications in the recycling of lamp phosphor waste, as well as other RE materials recycling schemes.…”

Section: Significancementioning

confidence: 99%

“…rare earth elements | lanthanides | separations | critical materials | coordination chemistry R are earth elements, La-Lu, Y, and Sc, have applications in many technologies, including permanent magnets (1)(2)(3)(4)(5), NiMH batteries (6)(7)(8)(9)(10), and lamp phosphors (11)(12)(13)(14). Limitations associated with their beneficiation and separations, especially their solvent-, waste-, and energy intensities, have contributed to the concentration of suppliers in the People's Republic of China.…”

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confidence: 99%

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Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures

Bogart

Cole

Boreen

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Rare earth (RE) metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare REs. To incentivize recycling, there is a clear need for the development of simple methods for targeted separations of mixtures of RE metal salts. Metal complexes of a tripodal hydroxylaminato ligand, TriNOx 3-, featured a size-sensitive aperture formed of its three η 2 -(N,O) ligand arms. Exposure of cations in the aperture induced a self-associative equilibrium comprising RE(TriNOx)THF and [RE(TriNOx)] 2 species. Differences in the equilibrium constants K dimer for early and late metals enabled simple separations through leaching. Separations were performed on RE1/RE2 mixtures, where RE1 = La-Sm and RE2 = Gd-Lu, with emphasis on Eu/Y separations for potential applications in the recycling of phosphor waste from compact fluorescent light bulbs. Using the leaching method, separations factors approaching 2,000 were obtained for early-late RE combinations. Following solvent optimization, >95% pure samples of Eu were obtained with a 67% recovery for the technologically relevant Eu/Y separation. (11)(12)(13)(14). Limitations associated with their beneficiation and separations, especially their solvent-, waste-, and energy intensities, have contributed to the concentration of suppliers in the People's Republic of China. Supply risks for these elements have emerged, particularly in the face of current and growing demand in the next 20 y (15, 16). Because the global marketplace for these elements is dominated by a single source (17), prices for primary rare earth (RE) materials are volatile (18). As a result, the US Department of Energy has classified many of these elements as "critical" (19). There is a clear need to find potential new supplies of these elements.Recent life cycle assessments have indicated that recycling of consumer materials is a promising alternative to conventional production processes (20). Despite this assertion, as recently as 2011, less than 1% of RE-containing materials were being recycled (21). These low recycling rates stem from a combination of sporadic collection procedures and lack of efficient separations and preprocessing steps (22)(23)(24)(25)(26)(27).To contribute to incentivizing the "urban mining" of REcontaining materials, we recently initiated efforts toward new, simplified methods in RE separations (28). Our initial work focused on the separation of neodymium (Nd) and dysprosium (Dy), two key components of neomagnets (Nd 2 Fe 14 B). We disclosed the development of the tripodal nitroxide ligand, [((2-t BuNO)C 6 H 4 CH 2 ) 3 N] 3− (TriNOx 3-), which induced a selfassociation equilibrium between monomeric Nd(TriNOx)THF/ dimeric [Nd(TriNOx)] 2 species. The position of this equilibrium was found to be strongly dependent on the size of the RE cation. We showed proof of concept that differences in the self-association equilibrium constants between Nd and Dy could be exploited to achieve 95% pure materials through a simple leachi...

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Section: Significancementioning

confidence: 99%

mentioning

confidence: 99%

Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures

Bogart

Cole

Boreen

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…NdFeB magnet used in high-temperature applications, such as motors in electric vehicles and direct-drive wind turbines, 2,3) have dysprosium (Dy) content of up to 10 mass% because dysprosium increases the intrinsic coercivity of NdFeB magnets at higher temperatures. 4) Dysprosium is categorized as one of the most critical elements in the short and long term owing to the increasing demand for electric vehicles. 3,[5][6][7][8][9] Therefore, the recovery and recycling of dysprosium from end-of-life NdFeB magnets have attracted increasing attention.…”

Section: Introductionmentioning

confidence: 99%

Application of Portable Total-Reflection X-Ray Fluorescence Spectrometer to Analysis of Dysprosium in Neodymium-Iron-Boron Magnet

et al. 2016

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Dysprosium (Dy) is expected to be recovered from end-of-life neodymium-iron-boron (NdFeB) magnets in the near future because of its worldwide shortage. Therefore, the rapid on-site elemental analysis of dysprosium in end-of-life NdFeB magnets is required. Here, we report a method of measuring the dysprosium composition in a NdFeB magnet on-site using a portable total-reflection X-ray fluorescence (TXRF) spectrometer. This method leads to drastic reduction of dysprosium loss caused by dissolving a NdFeB magnet because the portable TXRF spectrometer requires a small sample volume for measurement and its detection limit is as low as the ppb level. A NdFeB magnet was dissolved into hydrochloride acid and then iron in the solution was extracted using 4-methyl-2-pentanone (methyl isobutyl ketone: MIBK). Yttrium oxide (Y 2 O 3 ) and a diluted standard solution of rubidium (Rb) were added to the solution as internal standards. We measured the X-ray intensities of dried residue of the solution using a portable TXRF spectrometer. Dy Lα line was clearly detected in the solution, whereas it overlapped with Fe Kα line in the solution before the MIBK extraction process. The dysprosium composition in the NdFeB magnet was determined from the measured intensities of Dy Lα, Y Kα, and Rb Kα, the relative sensitivities of dysprosium and yttrium to rubidium for the portable TXRF spectrometer, and the weights of the dissolved NdFeB magnet and yttrium oxide. The calculated dysprosium composition was in good agreement with that obtained by conventional ICP-AES.KEY WORDS: total-reflection X-ray fluorescence; neodymium-iron-boron magnet; dysprosium; portable analyzer; methyl isobutyl ketone; on-site analysis.

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“…Neodymium-iron-boron (Nd-Fe-B) sintered magnets were invented by Dr. Masato Sagawa et al 1) in 1983 and have been widely used worldwide because of their high magnetic properties. Unlike ferrite magnets, the coercivity of Nd-Fe-B magnets decreases at high temperature.…”

Section: Introductionmentioning

confidence: 99%

Effects of Grain Boundary Phase on Coercivity of Dysprosium-Free Rare Earth Magnet

et al. 2016

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As a part of the challenge of reducing the use of scarce rare-earth elements in magnets, a Dy-free Nd-Fe-B magnet with the remanence and coercivity of 1370 mT and 1830 kA/m, respectively, was investigated. The grain boundary was composed of mainly two phases, R 6 T 13 M and R-rich phases. The R 6 T 13 M phase formed at around 750 to 1000 K, and in that temperature range, coercivity improved and remanence decreased. By increasing the amount of grain boundary phases to 17.3 at% R addition, coercivity higher than 1990 kA/m (25 kOe) was realized.

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Permanent magnet materials based on the rare earth-iron-boron tetragonal compounds

Cited by 748 publications

References 16 publications

Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures

Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures

Application of Portable Total-Reflection X-Ray Fluorescence Spectrometer to Analysis of Dysprosium in Neodymium-Iron-Boron Magnet

Effects of Grain Boundary Phase on Coercivity of Dysprosium-Free Rare Earth Magnet

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