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Tokushige M.,Doshisha University | Nishikiori T.,I MSEP Co. | Lafouresse M.C.,Kyoto University | Michioka C.,Kyoto University | And 3 more authors.
Electrochimica Acta | Year: 2010

Magnetic nanoparticles of FePt intermetallic compound were formed in molten LiCl-KCl-CsCl electrolyte under 1 atm of Ar atmosphere by plasma-induced cathodic discharge electrolysis. By utilizing the displacement reaction between the Fe(0) and Pt(II), FePt intermetallic compound nanoparticles were obtained from the melt. The displacement reaction produced small primary particles that considerably aggregated to form larger secondary particles. The coercivity of the obtained FePt intermetallic compound nanoparticle increased with a longer residence time in the melt. The coercivity of the FePt intermetallic compound nanoparticle obtained after a residence time of 3 h was measured to be 199 mA m-1. FePt intermetallic compound nanoparticles could also be obtained by the co-depositing Fe and Pt from Fe(II) and Pt(II) in the melt. In this case, the primary particle size distribution became broader, but the aggregation of primary particles was suppressed. The coercivity of the obtained FePt intermetallic compound nanoparticles showed a quite high value of 245 mA m -1 that did not depend on the residence time. © 2010 Elsevier Ltd. All rights reserved. Source


Tokushige M.,Doshisha University | Hongo H.,Doshisha University | Nishikiori T.,I MSEP Co. | Ito Y.,Doshisha University
Journal of the Electrochemical Society | Year: 2012

Sm-Co intermetallic compound nanoparticles were obtained by utilizing plasma-induced cathodic discharge electrolysis in molten chloride electrolyte under a 1 atm Ar atmosphere. To form intermetallic nanoparticle, an electrochemical implantation method was adopted. Before conducting electrochemical implantation, we investigated the electrolytic condition to form Co nanoparticle to be used as a precursor. The size and crystal structure of the obtained Co nanoparticle strongly depended on the melt temperature. Hexagonal petaline ε-Co nanoparticles were obtained below 400°C, and spherical α-Co nanoparticles were obtained above 400°C. The size of the obtained spherical α-Co particle increased from 112 to 230 nm with increasing melt temperature. Using spherical α-Co nanoparticles, which were formed at 450°C in the melt by plasma-induced cathodic discharge electrolysis and piled-up on the Mo plate as a working electrode, SmCo 2 and SmCo 3 intermetallic nanoparticles were obtained by electrochemical implantation of Sm into α-Co nanoparticles. © 2011 The Electrochemical Society. Source


Serizawa N.,Japan Central Research Institute of Electric Power Industry | Miyashiro H.,Japan Central Research Institute of Electric Power Industry | Takei K.,Japan Central Research Institute of Electric Power Industry | Ikezumi T.,Doshisha University | And 2 more authors.
Journal of the Electrochemical Society | Year: 2012

The dissolution behavior of ammonia (NH 3) in a molten LiCl-KCl-CsCl system was studied in order to determine the feasibility of low-energy NH 3 production via electrochemical synthesis in a high temperature molten salt system. In the presence of nitride ion (N 3-), a portion of NH 3 chemically dissolved in the melt as imide (NH 2-) and amide (NH 2 -) anions formed by the reaction between N 3- and NH 3. Although the dissolved NH 2 - anion thermally decomposed to form NH 3 and NH 2- anion, this phenomena may lower the yield of electrochemical NH 3 production. The dissolved NH 3 can be recovered by supplying hydrogen or water vapor to the melt. The anodic reaction between N 3- and H 2 to form NH 3 at a hydrogen gas-diffusion electrode was also examined and the NH 3 yield was estimated. Although the competing N 2 evolution reaction occurred at potentials more positive than 1.2 V vs. Li(I)Li, the conversion of Li 3N approached 70%, following the recovery processes. © 2012 The Electrochemical Society. Source


Tokushige M.,Doshisha University | Nishikiori T.,I MSEP Co. | Ito Y.,Doshisha University
Journal of the Electrochemical Society | Year: 2010

Fine nanoparticles of Ni were formed in molten LiCl-KCl-CsCl electrolyte under 1 atm of Ar atmosphere by plasma-induced cathodic discharge electrolysis using the rotating disk anode-type electrolytic cell. The relations between the size of the formed nanoparticles and the electrolysis conditions, such as the rotation speed of the disk and the electrolysis current value, were investigated. Ni nanoparticles with diameters of less than 10 nm were obtained at a rotation speed higher than 2000 rpm. The size of the obtained Ni nanoparticles depends on the rotation speed of the disk but not on the electrolysis current value. Based on the obtained results, the particle growth process just under the discharge is discussed. © 2010 The Electrochemical Society. Source


Tokushige M.,Doshisha University | Matsuura A.,Doshisha University | Nishikiori T.,I MSEP Co. | Ito Y.,Doshisha University
Journal of the Electrochemical Society | Year: 2011

Co-Pt intermetallic compound nanoparticles were formed by plasma-induced cathodic discharge electrolysis in molten LiCl-KCl electrolytes at 400-500°C under 1 atm of Ar atmosphere. Two different approaches were adopted: the displacement reaction between an electrochemically formed Co nanoparticle and Pt(II), and the codeposition of Co and Pt. In both approaches, special attention was paid to controlling the intermetallic composition of the Co-Pt particle by the experimental condition. It was found that both the composition of the particle and its magnetic property were affected by the residence time of the nanoparticle formed in the melt after terminating the electrolysis. In the displacement reaction, the Pt-rich phase (Co Pt3) was predominantly formed at an early stage of the residence, which changed to a Co-rich phase (Co3 Pt) when the residence time became longer. The coercivity of the obtained particle was 54.1 kA m-1 at 400°C and was 64.9 kA m-1 at 500°C. In the case of the codeposition, the composition of the Co-Pt nanoparticle also changed from the Pt-rich phase to the Co-rich phase with the long residence time after terminating the electrolysis. The coercivity of the obtained particle showed a higher value (375 kA m-1) than that of the particle obtained by the displacement reaction. © 2010 The Electrochemical Society. Source

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