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Journal of Applied Physics / Volume 111 / Issue 7 / PROCEEDINGS OF THE 56TH ANNUAL CONFERENCE ON MAGNETISM AND MAGNETIC MATERIALS / Hard Magnetic Materials

J. Appl. Phys. 111, 07A701 (2012); http://dx.doi.org/10.1063/1.3670054 (3 pages)

The partitioning of Dy and Tb in NdFeB magnets: A first-principles study

X. B. Liu and Z. Altounian

Centre for the Physics of Materials and Department of Physics, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 Canada

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(Received 21 September 2011; accepted 3 October 2011; published online 6 February 2012)

Doping with Dy/Tb is a current solution to improve the coercivity and the operating temperature of NdFeB magnets, by increasing the magnetocrystalline anisotropy of the (Nd, Dy/Tb)2Fe14B (2:14:1) phase. The efficiency of Dy/Tb doping depends on the distribution of Dy/Tb in the multi-phase microstructure of the NdFeB magnet. To understand and control the Dy/Tb redistribution, the partitioning of Dy/Tb between 2:14:1 and Nd-rich phases has been studied by a first-principles density functional calculation. The total energy calculations indicate that Dy and Tb prefer to enter the 4f sites in the 2:14:1 phase. The substitution energies of Dy and Tb in 2:14:1 are negative and are −0.35 eV/atom and −0.33 eV/atom, respectively, as Nd is replaced with 25% of Dy/Tb, i.e., stabilizing the 2:14:1 structure. However, the substitution energies of Dy and Tb in NdO have large positive values. They are 0.83 eV/atom and 0.73 eV/atom for Dy and Tb, respectively, when 25% of Nd is replaced by Dy/Tb. The results indicate that Dy/Tb prefer to enter the 2:14:1 phase rather than the Nd-rich phase (NdO). This is the thermodynamic origin for the selective occupation of Dy and Tb in the 2:14:1 structure which enhances the magnetic anisotropy field.

© 2012 American Institute of Physics

Article Outline

  1. INTRODUCTION
  2. METHODOLOGY AND COMPUTATIONAL DETAILS
  3. RESULTS AND DISCUSSION

KEYWORDS, PACS, and IPC

Keywords

ab initio calculations, boron alloys, coercive force, crystal microstructure, density functional theory, doping, dysprosium alloys, iron alloys, magnetic anisotropy, neodymium alloys, permanent magnets, terbium alloys, thermodynamic properties, total energy

PACS

  • 75.30.Gw

    Magnetic anisotropy

  • 71.15.Mb

    Density functional theory, local density approximation, gradient and other corrections

  • 71.15.Nc

    Total energy and cohesive energy calculations

  • 61.72.U-

    Doping and impurity implantation

  • 75.50.Vv

    High coercivity materials

International Patent Classification (IPC)

  • C22C38/00

    Ferrous alloys, e.g. steel alloys

  • C30B31/00

    Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor

  • H01F1/00

    Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties

ARTICLE DATA

Digital Object Identifier
http://dx.doi.org/10.1063/1.3670054

PUBLICATION DATA

ISSN

0021-8979 (print)  
1089-7550 (online)

Publisher

$abstract.society.value is a Member of CrossRef American Institute of Physics

For access to fully linked references, you need to log in.
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