2Flux growth and characterization of Ce-substituted Nd₂Fe₁₄B single crystals

Single crystals of (Nd_1−xCe_x)₂Fe₁₄B, some reaching ∼6×8×8mm³ in volume, are grown out of Fe-(Nd, Ce) flux. This crystal growth method allows for large (Nd_1−xCe_x)₂Fe₁₄B single crystals to be synthesized using a simple flux growth procedure. Chemical and structural analyses of the crystals indicate that (Nd_1−xCe_x)₂Fe₁₄B forms a solid solution until at least x=0.38 with a Vegard-like variation of the lattice constants with x. Refinements of single crystal neutron diffraction data indicate that Ce has a slight site preference (7:3) for the 4g rare earth site over the 4f site. Magnetization measurements at 300 K show only small decreases with increasing Ce content in saturation magnetization (M_s) and anisotropy field (H_A), and Curie temperature (T_C). First principles calculations are carried out to understand the effect of Ce substitution on the electronic and magnetic properties. For a multitude of applications, it is expected that the advantage of incorporating lower-cost and more abundant Ce will outweigh the small adverse effects on magnetic properties. Ce-substituted Nd₂Fe₁₄B is therefore a potential high-performance permanent magnet material with substantially reduced Nd content.