Quantitative evaluation of site preference in Dy-substituted Nd2Fe14B

We compared site occupancies of Dy ion in (Nd1−xDyx)2Fe14B (x=0.133,0.5), derived from powder neutron diffraction data, with theoretical results obtained from a combination of ab initio and thermodynamic calculations. Neutron diffraction showed that the Dy ion favors the 4f site with smaller Wigner-Seitz atomic cell for both samples, as partly reported in literature [Yelon et al., J. Appl. Phys. 60 (1986) 2982]. This site preference was quantitatively reproduced by combining ab initio calculation, giving Gibbs energy at zero temperature, and thermodynamic calculation, considering the entropy effect in the heat treatment process of the samples. The good agreement between experimental and theoretical values confirms the validity of this combined method to evaluate the site preference of (Nd1−xDyx)2Fe14B with arbitrary Dy concentration.