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

TitleSite-preference and valency for rare-earth sites in (R-Ce)(2)Fe14B magnets
Publication TypeJournal Article
Year of Publication2013
AuthorsAlam A, Khan M, McCallum RW, Johnson DD
Journal TitleApplied Physics Letters
Volume102
Pages042402
Date Published01
Type of ArticleArticle
ISBN Number0003-6951
Accession NumberWOS:000314723600049
KeywordsCERIUM, nd2fe14b, total-energy
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]

URL<Go to ISI>://WOS:000314723600049
DOI10.1063/1.4789527