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

Journal Article · Mon Jan 28 00:00:00 EST 2013 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4789527· OSTI ID:1211319

Alam, A; Khan, M; McCallum, RW; Johnson, DD

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]

• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• DOE Contract Number: 0472-1526
• OSTI ID: 1211319
• Journal Information: Applied Physics Letters, Vol. 102, Issue 4; ISSN 0003-6951
• Country of Publication: United States
• Language: English