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Title: Site-preference and valency for rare-earth sites in (R-Ce)(2)Fe14B magnets

Abstract

Rare-earth (R) permanent magnets of R2Fe14B have technological importance due to their high energy products, and they have two R-sites (Wyckoff 4f and 4g, with four-fold multiplicity) that affect chemistry and valence. Designing magnetic behavior and stability via alloying is technologically relevant to reduce critical (expensive) R-content while retaining key properties; cerium, an abundant (cheap) R-element, offers this potential. We calculate magnetic properties and Ce site preference in (R1-xCex)(2)Fe14B [R = La, Nd] using density functional theory (DFT) methods-including a DFT+U scheme to treat localized 4f-electrons. Fe moments compare well with neutron data-almost unaffected by Hubbard U, and weakly affected by spin-orbit coupling. In La2Fe14B, Ce alloys for 0 <= x <= 1 and prefers smaller R(4f) sites, as observed, a trend we find unaffected by valence. Whereas, in Nd2Fe14B, Ce is predicted to have limited alloying (x <= 0.3) with a preference for larger R(4g) sites, resulting in weak partial ordering and segregation. The Curie temperatures versus x for (Nd, Ce) were predicted for a typical sample processing and verified experimentally. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789527]

Authors:
; ; ;
Publication Date:
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1211319
DOE Contract Number:  
0472-1526
Resource Type:
Journal Article
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 102; Journal Issue: 4; Journal ID: ISSN 0003-6951
Country of Publication:
United States
Language:
English

Citation Formats

Alam, A, Khan, M, McCallum, RW, and Johnson, DD. Site-preference and valency for rare-earth sites in (R-Ce)(2)Fe14B magnets. United States: N. p., 2013. Web. doi:10.1063/1.4789527.
Alam, A, Khan, M, McCallum, RW, & Johnson, DD. Site-preference and valency for rare-earth sites in (R-Ce)(2)Fe14B magnets. United States. doi:10.1063/1.4789527.
Alam, A, Khan, M, McCallum, RW, and Johnson, DD. Mon . "Site-preference and valency for rare-earth sites in (R-Ce)(2)Fe14B magnets". United States. doi:10.1063/1.4789527.
@article{osti_1211319,
title = {Site-preference and valency for rare-earth sites in (R-Ce)(2)Fe14B magnets},
author = {Alam, A and Khan, M and McCallum, RW and Johnson, DD},
abstractNote = {Rare-earth (R) permanent magnets of R2Fe14B have technological importance due to their high energy products, and they have two R-sites (Wyckoff 4f and 4g, with four-fold multiplicity) that affect chemistry and valence. Designing magnetic behavior and stability via alloying is technologically relevant to reduce critical (expensive) R-content while retaining key properties; cerium, an abundant (cheap) R-element, offers this potential. We calculate magnetic properties and Ce site preference in (R1-xCex)(2)Fe14B [R = La, Nd] using density functional theory (DFT) methods-including a DFT+U scheme to treat localized 4f-electrons. Fe moments compare well with neutron data-almost unaffected by Hubbard U, and weakly affected by spin-orbit coupling. In La2Fe14B, Ce alloys for 0 <= x <= 1 and prefers smaller R(4f) sites, as observed, a trend we find unaffected by valence. Whereas, in Nd2Fe14B, Ce is predicted to have limited alloying (x <= 0.3) with a preference for larger R(4g) sites, resulting in weak partial ordering and segregation. The Curie temperatures versus x for (Nd, Ce) were predicted for a typical sample processing and verified experimentally. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789527]},
doi = {10.1063/1.4789527},
journal = {Applied Physics Letters},
issn = {0003-6951},
number = 4,
volume = 102,
place = {United States},
year = {2013},
month = {1}
}