Mossbauer spectroscopy study of the rhombohedral phase Y2Fe17Nx with intermediate nitrogen content (0 <= x <= 2.8)

Mossbauer spectra were obtained at 15 K from samples of rhombohedral Y2Fe17 and its nitrides Y2Fe17Nx, with nominal nitrogen contents of x = 0.6, 1.2, 1.8, 2.4, and 2.8. The spectra have been analyzed using a model which is c onsistent with the crystallographic structure and with magnetization that l ies along a general direction in the hexagonal basal plane. The hyperfine f ield values for the four crystallographically inequivalent Fe sites change differently upon nitrogenation. For each of the Y2Fe17Nx samples with inter mediate N content, the spectrum can be described as a superposition of two components, one from the nitrided shell of the sample particle and one from the outer portion of its unnitrided core. These results, along with earlie r Fe-57 nuclear magnetic resonance measurements, yield a consistent picture for the two-phase configuration of Y2Fe17Nx and its hyperfine field behavi or. (C) 1999 American Institute of Physics. [S0021-8979(99)55808-8].