Structural and magnetic investigation of (R1−xR′x)2Fe17−yCoyNz(R1−xR′x)2Fe17−yCoyNz powders by Mössbauer spectrometry

(R1−xR′x)Fe17−yCoy(R1−xR′x)Fe17−yCoy powders were prepared by induction melting. Nitrogen (2.9 ± 0.1 atoms per formula unit) was inserted under a static nitrogen gas atmosphere. The nitrided powders have been investigated by 57Fe Mössbauer spectrometry and X-ray diffraction. The analyses show that the samples are composed of two phases: the nitrided (R1−xR′x)Fe17−yCoyNz(R1−xR′x)Fe17−yCoyNz phase and α-Fe. The variations of the Mössbauer hyperfine parameters of the nitrided phase are explained both by the lattice expansion and by the presence of nitrogen. The observed variations do not indicate an influence of the rare-earth on the isomer shift. Nitrogenation increases the hyperfine field at the Fe sites in agreement with the enhancement of the Curie temperature.