MOSSBAUER-SPECTRA AND MAGNETIC-PROPERTIES OF IRON NITRIDES

The iron nitrides Fe3N, Fe4N and Fe8N (impure) have been prepared by treating iron in NH3/H-2 gas mixtures followed by appropriate heat treatment. Fe8N has also been prepared by mechanical alloying. Mossbauer spectra are analysed in terms of iron sites with different nitrogen environments, and results are compared with magnetization measurements and band-structure calculations. Moments and hyperfine fields on sites with nitrogen neighbours are reduced by p-d hybridization, whereas the sites farthest from nitrogen have the lowest charge and the highest moments. There is no evidence of an exceptionally high magnetization in any of these compounds.