Effects of Fe substitution on structural and magnetic properties of the Nd2Co7-xFex compounds

Abstract The structural and magnetic properties of the Nd 2 Co 7− x Fe x compounds related to R m + n T 2 m +5 n series (R = rare earth, T = transition metal) were investigated by means of X-ray diffraction and magnetic measurements. The compounds crystallize in the Ce 2 Ni 7 -type structure with the space group P 6 3 / mmc between x  = 0.0 and 2.1. For higher Fe content the Nd 2 (CoFe) 7 either coexists with the Nd(CoFe) 3 phase ( x  > 2.1) or decomposes to Nd(CoFe) 3  + Nd 2 (CoFe) 17 ( x  > 2.4). The single phase Nd 2 Co 7− x Fe x compounds exhibit two spin-reorientation transitions (SRT) for x x x  ≥ 1.5. A magnetic phase diagram is constructed based on the magnetic measurements, thermogravimetry analysis under a low magnetic field and X-ray diffraction of magnetically aligned samples. The saturation magnetization of the compounds increases gradually first with the Fe content for x  ≤ 0.20, substantially for 0.20  x x  > 1.5, which can be elucidated by a depletion effect of d band electrons due to the substitution of Fe for Co and the spin-flipping due to an enhanced d band splitting.