Rare earth elements and permanent magnets (invited)

Dent, Peter C.

doi:10.1063/1.3676616

Cited by 153 publications

(79 citation statements)

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“…Traditionally the search for new permanent magnets has been focused mainly on the search for materials with large anisotropies, mainly based on rare-earth elements, e.g., SmCo 5 or Fe 14 Nd 2 B [42,[357][358][359][360][361][362][363][364][365]. However, the ever increasing demand for permanent magnets has triggered a shortage of rare-earth raw materials resulting in a significant increase in price.…”

Section: Permanent Magnetsmentioning

confidence: 99%

“…Permanent magnets are used in widespread applications ranging from household items (such as cell phones), industrial applications (e.g., motors, alternators) to high-technology devices (like nano-and micro-electromechanical systems -NEMS-MEMS-, new types of recording media or magnetoresistive random access memories -MRAM-) [42,[357][358][359][360][361][362][363][364]. Traditionally the search for new permanent magnets has been focused mainly on the search for materials with large anisotropies, mainly based on rare-earth elements, e.g., SmCo 5 or Fe 14 Nd 2 B [42,[357][358][359][360][361][362][363][364][365].…”

Section: Permanent Magnetsmentioning

confidence: 99%

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Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

et al. 2015

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A B S T R A C TThe applications of exchange coupled bi-magnetic hard/soft and soft/hard ferromagnetic core/shell nanoparticles are reviewed. After a brief description of the main synthesis approaches and the core/shell structural-morphological characterization, the basic static and dynamic magnetic properties are presented. Five different types of prospective applications, based on diverse patents and research articles, are described: permanent magnets, recording media, microwave absorption, biomedical applications and other applications. Both the advantages of the core/shell morphology and some of the remaining challenges are discussed.

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Section: Permanent Magnetsmentioning

confidence: 99%

Section: Permanent Magnetsmentioning

confidence: 99%

Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

et al. 2015

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“…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%

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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“…Amorphous films of the same * fridrik.magnus@physics.uu.se material exhibit lower magnetostriction, albeit at lower fields due to a reduced anisotropy [16,17]. Other high-anisotropy materials [18] such as crystalline SmCo also have a large magnetostriction although it is strongly dependent on the grain size [19]. It has been shown that a large anisotropy can even be induced in amorphous alloys of Sm and Co and it is tuneable over a large range through composition [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Magnetostrictive properties of amorphous SmCo thin films with imprinted anisotropy

et al. 2014

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We examine the magnetostriction in amorphous SmCo thin films with a composition in the range 4-27 at. % Sm. The magnetostriction increases significantly with increasing Sm content but is small compared to terbium-based ferromagnetic compounds, despite the large imprinted anisotropy. The magnetostriction and anisotropy both increase approximately linearly as the temperature is reduced. The magnetoelastic energy is found to be far smaller than the anisotropy energy so the magnetoelastic atomic displacements during growth cannot be the origin of the imprinted anisotropy. The anisotropy is only slightly altered by the application of large tensile stresses, indicating that the local strain fields involved in magnetostriction are not equivalent to the global strain produced by mechanical bending.

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Rare earth elements and permanent magnets (invited)

Cited by 153 publications

References 1 publication

Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

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

Magnetostrictive properties of amorphous SmCo thin films with imprinted anisotropy

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