Electrochemical behavior and electrodeposition of dysprosium in ionic liquids based on phosphonium cations

Kurachi, Akifumi; Matsumiya, Masahiko; Tsunashima, Katsuhiko; Kodama, Shun

doi:10.1007/s10800-012-0463-8

Cited by 70 publications

(48 citation statements)

References 23 publications

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“…25 We used a bath of 0.2 mol kg −1 Dy(TFSI) 3 in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide for electroplating Dy metal. Cyclic voltammetry of Dy on Au substrate.-Cyclic voltammograms of 0.147 M Dy(TFSI) 3 in BMPTFSI recorded at 25…”

Section: Resultsmentioning

confidence: 99%

“…The cathodic peak appearing around -1.25 V in the voltammograms is ascribed to the reduction of Dy(III) to Dy(0), as no other reductive processes could be observed. 25 The reduction of Dy in this system is irreversible, shown by the absence of an anodic peak corresponding to the oxidation of Dy(0). Irreversible behavior of the Dy plating process was also shown by Lodermeyer et al using a solution of dysprosium triflate and dimethylpyrrolidinium triflate dissolved in dimethylformamide (DMF).…”

Section: Journal Of Thementioning

confidence: 88%

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Electroplating Dysprosium from IL-Based Solutions: A Promising Electrochemical Step to Produce Stronger High Performance Nd(Dy)-Fe-B Sintered Magnets

Suppan

Ruehrig

Kanitz

et al. 2015

J. Electrochem. Soc.

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An electrodeposition replacement to the commonly used physical vapor deposition methods used in enhancing the coercivity of Nd-Fe-B sintered magnets has been proposed. Dysprosium was galvanostatically electroplated on Nd-Fe-B sintered magnets that were previously electrochemically coated with copper. Electroplated dysprosium films were characterized by X-ray photoelectron spectroscopy, depth profiling, scanning electron micrographs, and energy dispersive X-ray spectroscopy. XPS analysis after argon ion sputtering indicates that minor impurities are only superficial as their atomic fractions in the sample nearly disappear with increasing etching time. The electrochemistry of synthesized dysprosium bis(trifluromethylsulfonyl)imide dissolved in the air-and water-stable ionic liquid 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsuflonyl)imide was studied by cyclic voltammetry. Electroplating of metallic dysprosium was followed by a heat-treatment above the melting temperature of the Nd-rich phases of the sintered magnet base body whose magnetic characterization was performed in a hysteresis loop tracer for hard magnetic materials. Due to it being the highest energy product of any known magnet, Nd-Fe-B magnets are widely used in high performance electric machines. The energy product (BH) max, typically given in [kJoule/m 3 ] is the figure of merit for the maximum magnetic energy a permanent magnet can provide in a real application like an electrical motor. B denotes the magnetic flux density [in Tesla] in the material and H is the value of the magnetic field strength [in A/m] acting on the magnet. At zero field the magnet has a remanent polarization B r which gradually decreases with applied reverse fields, until the polarization changes direction (irreversibly) at negative field values of H cJ (=coercive field). The coercivity H cJ in Nd-Fe-B magnets decreases significantly with rising temperature and the operating temperature in motor applications can reach up to 200• C. 1 Magnet reversal or demagnetization of the permanent magnets has to be unconditionally avoided at any reverse field or thermal conditions during operation. The coercivity is the main material property limiting the application of high energy product Nd-Fe-B magnets. A method to overcome the risk of demagnetization at high temperatures is to further increase the coercivity of the material, so that H cJ and (BH) max still show adequate values at operating conditions. Up to now, this has been achieved by alloying heavy rare earth elements (HREE) such as dysprosium or terbium as substitution of light rare earth elements in the magnetic grains (Nd 2 Fe 14 B-phase) 2 on an industrial scale. HREE increase the magnetocrystalline anisotropy.3 Certain applications call for very high coercivity via substitution of Nd by Dy of up to about 10 wt%. However, substitution of LREEs by HREEs is not only very costly due to the scarcity of HREEs in comparison to Nd but causes a decrease in remanence B r due to anti-ferromagnetic coupling as well. A more efficient m...

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Section: Resultsmentioning

confidence: 99%

Section: Journal Of Thementioning

confidence: 88%

Electroplating Dysprosium from IL-Based Solutions: A Promising Electrochemical Step to Produce Stronger High Performance Nd(Dy)-Fe-B Sintered Magnets

Suppan

Ruehrig

Kanitz

et al. 2015

J. Electrochem. Soc.

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“…There are some reports about the electrochemical behavior and electrodeposition of RE elements such as La, Sm, Eu and Yb [7,8] in ILs. We have already demonstrated that the recovery process of Nd [9][10][11] and Dy [12,13] metals by electrodeposition using quaternary phosphonium and ammonium-based ILs, such as triethyl-pentyl-phosphonium bis(trifluoromethyl-sulfonyl)amide, [P 2225 ] [TFSA], and 2-hydroxy ethyl-trimethyl-ammonium bis(trifluoromethyl-sulfonyl)amide, [N 1112OH ] [TFSA]. In addition to the electrodeposition process using ILs, the wet separation process has been recently indispensable for the recycling of spent Nd-Fe-B magnets.…”

Section: Introductionmentioning

confidence: 96%

Solvation and electrochemical analyses of neodymium complexes in TFSA-based ionic liquids dissolving the nitrates synthesized from spent Nd–Fe–B magnets

2015

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“…However, reduction may occur in a molten salt, which does not contain water [10][11][12] . Therefore, we used a molten salt as the reaction medium.…”

Section: Introductionmentioning

confidence: 99%

Recovery of Dy from a Mixture of Nd, Fe, B and Dy by Electrolysis in Molten LiCl

2016

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The electrodeposition and recovery of Dy was attempted by chlorinating Dy with Cl 2 generated at the anode by electrolysis in molten LiCl, in which Fe, B, Nd and Dy powders were added, then reducing the Dy ions, which were ionized from the dysprosium chloride, at the cathode. When the electrolysis in the LiCl bath was carried out even after the Fe, B, Nd and Dy powders were added to the LiCl bath, the electrodeposition of these metals on the cathode did not occur, thus the metals could not be recovered when the electrolysis in the LiCl bath was carried out even after the Fe, B, Nd and Dy powders were added to the LiCl bath. The mass increase due to the electrodeposition of Dy was observed at the cathode in the LiCl bath in which DyF 3 was added. The mass of the material electrodeposited at the cathode was greater in the LiCl bath, in which the Fe, B, Nd and Dy powders were added with DyF 3 , in comparison to that in the bath with only DyF 3 . It was found from analyzing the electrodeposited material by an X-ray diffraction technique and an electron probe microanalyzer that the material consisted of a large amount of Dy and a small amount of B. Examination of the cation concentration in the molten salt after electrolysis using an inductively coupled plasma instrument revealed that the molten LiCl, into which DyF 3 and the metal powders were added, contained the highest number of Dy ions. Thus, metallic Dy was cationized during the electrolysis in the molten LiCl bath containing DyF 3 and the metal powders, then the cationized Dy was reduced at the cathode and precipitated as metallic Dy.

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Electrochemical behavior and electrodeposition of dysprosium in ionic liquids based on phosphonium cations

Cited by 70 publications

References 23 publications

Electroplating Dysprosium from IL-Based Solutions: A Promising Electrochemical Step to Produce Stronger High Performance Nd(Dy)-Fe-B Sintered Magnets

Electroplating Dysprosium from IL-Based Solutions: A Promising Electrochemical Step to Produce Stronger High Performance Nd(Dy)-Fe-B Sintered Magnets

Solvation and electrochemical analyses of neodymium complexes in TFSA-based ionic liquids dissolving the nitrates synthesized from spent Nd–Fe–B magnets

Recovery of Dy from a Mixture of Nd, Fe, B and Dy by Electrolysis in Molten LiCl

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