NITROGEN LOCATION IN R(2)FE(17) COMPOUNDS - AN NMR-STUDY

N-14, Y-89 and H-1 spin-echo NMR experiments have been carried out in order to study the nitrogen location in the R(2)Fe(17) lattice with R = Gd, Lu and Y. The observed N-14 spectrum for the Gd-compound indicat es that essentially all of the N atoms occupy the octahedral interstit ial sites. However, the 'two-peak' N-14 spectra for the Y-compounds an d, to a lesser degree the Lu-compound, indicate that some of the N ato ms enter the tetrahedral interstitial sites in addition to the octahed ral sites. A consideration of both N-14 and Y-89 spectra indicates tha t the probability for a N atom to enter a tetrahedral site in the Y2Fe 17 lattice is much smaller than that for octahedral site occupation. T his study reveals that the local structure of Y2Fe17Nx may change with the nitrogenation conditions.