First-principles study on formation mechanism of Nd-O for high coercivity magnets

2014 Fiscal Year Final Research Report

• Project/Area Number: 23560826
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural/Functional materials
• Research Institution: Tohoku University
• Principal Investigator: CHEN Ying 東北大学, 工学(系)研究科(研究院), 教授 (40372403)
• Project Period (FY): 2011-04-28 – 2015-03-31
• Keywords: 希土類磁石 / Nd-O / 粒界構造 / 生成機構 / 第一原理計算 / Cu

Outline of Final Research Achievements

To have a thorough understanding on the formation mechanism of disordered fcc-NdOx phase formed at the interface of Nd/Nd-Fe-B, and its relation to the surface coercivity, ground state analysis for whole oxygen concentration in Nd-O has been performed by combing the LSDA+U and the Cluster Expansion Method (CEM). Systematic calculations revealed that a sequent fcc-based structures formed by introducing oxygen vacancies into NdO is stable in almost all 0-50% oxygen concentration range, whereas in a series hcp-based structures developed from hp5-Nd2O3 no stable structure is observed, which coincides with the experiments very well. Large scale interface calculations show that the NdOx-fcc/Nd-dhcp is more stable, further explained the relation between the phase stability and coercivity. The stability and binding properties of the Cu-doped Cu-fcc-NdOx structures which was reported to be favorite for increasing coercivity are investigated.

Free Research Field

計算材料科学