Experimental and computational study on the phase formation and magnetic properties of Ce-La-Fe-B alloys

Highlights: • La substitution can avoid the formation of TbCu₇-type phase in Ce-Fe-B melt spun ribbons. • The 2:14:1 main phase begin to decompose when the La substitution amount reached to 50 at%. • La substitution lower the structural stability and cause the lattice expansion. • Magnetic properties were enhanced significantly by La substitution. • The mechanism of enhanced Ms are explained by the magnetovolume effect according to the DFT calculation. Low-cost Ce-Fe-B permanent magnets has stimulated considerable research efforts as the most potential alternative for those relying on expensive rare earth elements Nd, Pr, Dy, Tb. However, the intrinsic magnetic properties of Ce-Fe-B alloys are much inferior to those of Nd-Fe-B alloys. In this paper, we substitute Ce with La to get more advanced magnetic properties. The phase stability and magnetic properties of (Ce_1−xLa_x)₂Fe₁₄B (x = 0–0.7) compounds prepared by melt spinning technique are studied systematically by experiments and first principle calculations. The calculated substitution energy is positive which indicates that La substitution will lower the structural stability and the decomposition of 2:14:1 phase was founded from the X-ray diffraction patterns. The enhancement of the magnetic properties can be explained by the magnetovolume effect. According to the computational result, the unit cell volume expands slightly with La substitution, which agrees well with the fact that the radius of La is larger than Ce. Furthermore, the moments of Fe are volume-dependent and increase with volume expanding.