Site-preference and valency for rare-earth sites in (R-Ce)2Fe14B magnets
- Ames Laboratory
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)2Fe14B [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.
- Research Organization:
- Ames Lab., Ames, IA (United States)
- Sponsoring Organization:
- USDOE Advanced Research Projects Agency - Energy (ARPA-E)
- DOE Contract Number:
- DE-AC02-07CH11358
- OSTI ID:
- 1080070
- Report Number(s):
- IS-J 7933
- Journal Information:
- Applied Physics Letters, Vol. 102, Issue 4; ISSN 0003-6951
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- United States
- Language:
- English
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