The effect of nitrogen insertion in the Nd2−xGdxFe17Ny gadolinium substituted compounds

Structural and magnetic investigation of powders by Mössbauer spectrometry

“…This is in agreement with the variation of T c with the composition: the relative increase of T c is lower for Sm 2 Fe 17 than for Nd 2 Fe 17 (400-780 K upon nitrogenation of Sm 2 Fe 17 [20], compared with 330-743 K upon nitrogenation of Nd 2 Fe 17 [6]). The same observation can be made for the Co-containing samples: the relative increase of T c is lower for Nd 1.5 Gd 0.5 Fe 16 Co than for Nd 2 Fe 16 Co (504-795 K upon nitrogenation of Nd 1.5 Gd 0.5 Fe 16 Co [12], compared with 441-773 K upon nitrogenation of Nd 2 Fe 16 Co [12]).…”

“…The insertion of nitrogen has been carried out in static nitrogen gas under a pressure of 15 MPa at 733 K for 24 h. The nitrogen content was checked by the weight increase in the samples. It was found to be 2.9 ± 0.1 atoms per formula unit [5,6,12]. For these experiments a Brucker D8 powder diffractometer with the Co(K␣1) radiation ( = 0.1788970 nm) was used.…”

“…For example, T c increases from 400 K for Sm 2 Fe 17 up to 780 K for Sm 2 Fe 17 N 3 [20], and the average hyperfine field increases from 21.55 T for Sm 2 Fe 17 to 33.15 T for Sm 2 Fe 17 N 3 (Table 3). For NdGdFe 17 , nitrogenation increases T c from 400 K up to 768 K for NdGdFe 17 N 2.8 [6], and the room temperature magnetization increases from 24.10 B /fu to 35.08 B /fu [6].…”

“…Nitrogenation induces a volume expansion of the lattice between 3% and 7%, leading to a large enhancement of both Curie temperature and magnetization [5,6]. Like their unnitrided counterparts, the R 2 Fe 17 N z compounds crystallize in a rhombohedral Th 2 Zn 17 structure for light rare-earths (Pr, Nd, Sm) [5,6], the nitrogen atoms being located predominantly on the 9e site [7].…”

“…The structure of the samples has been investigated by X-ray diffraction. Magnetic measurements have been previously done on the same samples to determine Curie temperature and saturation magnetization [5,6,12].…”