Rare‐earth Transition‐metal Magnets

Rodewald, W.

doi:10.1002/9780470022184.hmm406

Cited by 8 publications

(9 citation statements)

References 127 publications

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“…In Table 1, we present the EDS obtained results in red highlighted areas in For both characterized samples, the RE content (Nd + Pr) was 29% and the iron content was 66% (Table 1). These values are close to the values of the alloys (Nd-Pr)-Fe-B observed in the literature [7].…”

Section: Electrochemical Testssupporting

confidence: 91%

“…These phases in magnet microstructure have different corrosion potentials that lead a poor corrosion resistance [6]. It is possible to improve the corrosion resistance by adding alloying elements such as Co, Nb, V, Mo, Cu and Ga in the magnet [7] or applying coatings. The most common protective coatings are the metallic, conversion (phosphatized as a temporary protection) and organic (paint) layers [8].…”

Section: Introductionmentioning

confidence: 99%

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Permanent Rare-Earth Magnets—The Need to Protect Them against Corrosion

Santos¹,

Panossian²

2019

MSA

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The RE-Fe-B permanent magnets have a complex microstructure and they are susceptible to corrosion process. In this paper, the commercial nickel coatings adhesion was investigated. The microstructure of the RE-Fe-B without coating was analyzed by scanning electronic microscopy and electrochemical techniques. The interface magnet/coating was studied by scanning electron microscopy and the nickel-plated Nd-Fe-B commercial magnets were tested in a salt spray chamber. The ferromagnetic and RE-rich phases were observed. After the anodic polarization curve, a strong intergranular corrosion was observed and the RE-rich phase was preferentially attacked. The interface magnet/Ni coating presented intergranular corrosion that can affect the nickel coating adherence. This attack had probably occurred during the electrodeposition process. Not all the samples suffered localized corrosion during the salt spray tests and the Ni triple-layer coating presented a few corrosion points. RE-Fe-B alloy magnets need to be protected with appropriate coatings to each environment to which they will be exposed and the protective coating must not be damaged.

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Section: Electrochemical Testssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Permanent Rare-Earth Magnets—The Need to Protect Them against Corrosion

Santos¹,

Panossian²

2019

MSA

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“…36 The remaining non-hydrogen atoms were located from successive difference Fourier map calculations. The refinements were carried out by using full-matrix least-squares techniques on F 2 , minimizing the function (F o À F c ) 2 , where the weight is defined as…”

Section: X-ray Crystallographic Studies Of 1à5mentioning

confidence: 99%

Novel Lanthanide-Based Polymeric Chains and Corresponding Ultrafast Dynamics in Solution

et al. 2011

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Two types of structurally related one-dimensional coordination polymers were prepared by reacting lanthanide trichloride hydrates [LnCl(3)·(H(2)O)(m)] with dibenzoylmethane (Ph(2)acacH) and a base. Using cesium carbonate (Cs(2)CO(3)) and praseodymium, neodymium, samarium, or dysprosium salts yielded [Cs{Ln(Ph(2)acac)(4)}](n) (Ln = Pr (1), Nd (2), Sm (3), Dy (4)) in considerable yields. Reaction of potassium tert-butoxide (KOtBu) and the neodymium salt [NdCl(3)·(H(2)O)(6)] with Ph(2)acacH resulted in [K{Nd(Ph(2)acac)(4)}](n) (5). All polymers exhibit a heterobimetallic backbone composed of alternating lanthanide and alkali metal atoms which are bridged by the Ph(2)acac ligands in a linear fashion. ESI-MS investigations on DMF solutions of 1-5 revealed a dissociation of all the five compounds upon dissolution, irrespective of the individual lanthanide and alkali metal present. Temporal profiles of changes in optical density were acquired performing pump/probe experiments with DMF solutions of 1-5 via femtosecond laser spectroscopy, highlighting a lanthanide-specific relaxation dynamic. The corresponding relaxation times ranging from seven picoseconds to a few hundred picoseconds are strongly dependent on the central lanthanide atom, indicating an intramolecular energy transfer from ligands to lanthanides. This interpretation also demands efficient intersystem crossing within one to two picoseconds from the S(1) to T(1) level of the ligands. Magnetic studies show that [Cs{Dy(Ph(2)acac)(4)}](n) (4) has slow relaxation of the magnetization arising from the single Dy(3+) ions and can be described as a single-ion single molecule magnet (SMM). Below 0.5 K, hysteresis loops of the magnetization are observed, which show weak single chain magnet (SCM) behavior.

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“…The excess of neodymium with respect to the stochiometric composition of the magnetic Nd 2 Fe 14 B-phase is usually needed to get the desired structure by liquid phase sintering. This leads to the microstructure where grains of the magnetic matrix phase Nd 2 Fe 14 B are surrounded by neodymium-rich constituents [2]. Developments of the manufacturing process have led to the use of strip casting of the raw material instead of conventional book moulding; strip casting produces a more homogenous microstructure and requires less rare-earth elements [3].…”

Section: Introductionmentioning

confidence: 99%