Hyperfine interactions in hexagonal ε-Fe6Ny phase investigated by Mössbauer spectroscopy and ab initio calculations

Both Mössbauer measurements and ab initio calculations are used to investigate the trends of hyperfine interactions (isomer shift (IS) and hyperfine field (HFF)) with the variation of nitrogen content for ε-Fe6Ny phase in the whole composition range, i.e., y = 1–3. Low-temperature (4.2 K) Mössbauer experiments on hexagonal ε-Fe6Ny (y < 2) powder samples are performed. The dependencies of the low-temperature IS and HFF (especially for samples with y < 2) on the iron atom surroundings An (n = 0, 1, 2, 3 nitrogen atoms) and the nitrogen content agree well with the ab initio results, in particular the results without spin orbital coupling. The present work indicates that the measured values of HFF for ε-Fe6Ny phase are influenced by both the iron atomic volume and the temperature (with respect to the Curie temperature of the ε phase). The values of IS are generally increasing functions of An and nitrogen content of the ε phase.