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Near theoretical ultra-high magnetic performance of rare-earth nanomagnets via the synergetic combination of calcium-reduction and chemoselective dissolution

Title
Near theoretical ultra-high magnetic performance of rare-earth nanomagnets via the synergetic combination of calcium-reduction and chemoselective dissolution
Author
김종렬
Issue Date
2018-10
Publisher
NATURE PUBLISHING GROUP
Citation
SCIENTIFIC REPORTS, v. 8, Article no. 15656
Abstract
Rare earth permanent magnets with superior magnetic performance have been generally synthesized through many chemical methods incorporating calcium thermal reduction. However, a large challenge still exists with regard to the removal of remaining reductants, byproducts, and trace impurities generated during the purifying process, which serve as inhibiting intermediates, inducing productivity and purity losses, and a reduction in magnetic properties. Nevertheless, the importance of a post-calciothermic reduction process has never been seriously investigated. Here, we introduce a novel approach for the synthesis of a highly pure samarium-cobalt (Sm-Co) rare earth nanomagnet with near theoretical ultra-high magnetic performance via consecutive calcium-assisted reduction and chemoselective dissolution. The chemoselective dissolution effect of various solution mixtures was evaluated by the purity, surface microstructure, and magnetic characteristics of the Sm-Co. As a result, NH4Cl/methanol solution mixture was only capable of selectively rinsing out impurities without damaging Sm-Co. Furthermore, treatment with NH4Cl led to substantially improved magnetic properties over 95.5% of the M-s for bulk Sm-Co. The mechanisms with regard to the enhanced phase-purity and magnetic performance were fully elucidated based on analytical results and statistical thermodynamics parameters. We further demonstrated the potential application of chemoselective dissolution to other intermetallic magnets.
URI
https://www.nature.com/articles/s41598-018-33973-zhttp://repository.hanyang.ac.kr/handle/20.500.11754/121548
ISSN
2045-2322
DOI
10.1038/s41598-018-33973-z
Appears in Collections:
COLLEGE OF ENGINEERING SCIENCES[E](공학대학) > MATERIALS SCIENCE AND CHEMICAL ENGINEERING(재료화학공학과) > Articles
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