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First-principles calculation of amorphous grain boundary phase in Nd-Fe-B sintered magnet

Junjiro Kanamori Memorial International Symposium

2017年9月28日(木)

寺澤麻子、合田義弘

Abstract

Improvement of Nd-Fe-B magnets without heavy rare earth elements is one of the topics of increasingimportance in the applied physics and materials science. The key for high-coercivity Nd-Fe-B magnetslies in the Nd-rich grain boundary (GB) phases [1]. However, the details of structural and magneticproperties of those GB phases are not clarified yet. Some experiments revealed the relationshipbetween the crystallinity of GB phases and the relative angles between the interfaces and the c-planeof neighboring grains [2], which indicates the complexity of the physics in grain boundary phases in Nd-Fe-B magnets.Considering these backgrounds, we targeted the amorphous grain boundary phases and their interfaceswith the main phase. First, we performed melt-quench molecular dynamics (MD) simulation [3] to createan amorphous Nd-Fe alloy. For this purpose, we adopted OpenMX [4] for ab-initio MD with finitetemperature. Figure (a) shows the radial distribution function (RDF) of the created amorphous alloy.Each element pair component in RDF shows typical amorphous-like oscillatory feature. Second, wedeveloped a scheme to determine antiferromagnetic-like spin configurations for amorphous structuresfrom those atomic distances. In Fig. (b), we show the schematics of obtained ferromagnetic andantiferromagnetic-like spin configurations.


研究活動

文部科学省

文部科学省
元素戦略プロジェクト(活動紹介)
NIMS磁石パートナーシップ

元素戦略拠点

触媒・電池元素戦略拠点
触媒・電池元素戦略研究拠点 (京都大学)
東工大元素戦略拠点
東工大元素戦略拠点 (東京工業大学)
構造材料元素戦略研究拠点
構造材料元素戦略研究拠点 (京都大学)
高効率モーター用磁性材料技術研究組合
高効率モーター用 磁性材料技術研究組合