Influence of strain and substitution on magnetocrystalline anisotropy of R2Fe14B (R=Pr, Dy and Y)

Abstract

Abstract The intermetallic rare earth-transition metal ( R - T ) compound Nd 2 Fe 14 B has a large energy density and is an industrially important permanent magnet material. Its low Curie Temperature ( T C ) though limits its use for electric motor applications. To improve its high temperature permanent magnetic properties, the coercive field ( H C ) should be enhanced, which can be achieved by influencing intrinsic atomistic properties such as saturation magnetization ( M S ) and magnetocrystalline anisotropy energy (MAE). Strain effects and substitution are two important methods for influencing M S and MAE. Using numerical methods based on density functional theory, firstly M S and MAE of three R 2 Fe 14 B compounds with R = P r , D y and Y are calculated at 0 K. Further, the influence of changing the lattice parameter ratio c / a on MAE is studied. For increasing c / a , MAE of Y 2 F e 14 B and Pr 2 F e 14 B remains nearly constant, while MAE of Dy 2 F e 14 B decreases monotonously, up to 40 % per 1 % change in c / a . In the next step, 50 % of the R - atoms are substituted. For Pr 2 F e 14 B , MAE decreases with substitution of Dy and Y ; for Dy 2 F e 14 B it increases with Pr but decreases with Y ; for Y 2 F e 14 B it increases with Pr and Dy . The nucleation field ( H N ) of the substituted phases are estimated for different microstructures and visually compared to the non-substituted compounds, showing a large H N for P r D y F e 14 B . Further, based on DOS plots of the Y - D y F e 14 B system, the contribution of different atoms and atomic sites to MAE is discussed, and by visualizing the electronic density contours, the influence of substitution on Fe - atoms in Dy 2 F e 14 B and D y Y F e 14 B is studied.