Site-preference and valency for rare-earth sites in (R-Ce)2Fe14B magnets
Date
Authors
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Research Projects
Organizational Units
Journal Issue
Is Version Of
Versions
Series
Department
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 propertiesand 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.
Comments
The following article appeared in Appl Phys. Lett. 102, 042402 (2013) and may be found at http://dx.doi.org/10.1063/1.4789527.