Möussbauer studies of electronic properties of iron impurities in hexagonal close-packed metals

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Abstract
Beryllium specimens containing 0·012 at. % of 57Fe were studied by Mossbauer spectroscopy at various temperatures from 75 to 1200 K. The change of the quadrupole splitting, as a function of the temperature, cannot be explained by the variation of the anisotropy in the host metal. The best fit to the experimental values is obtained by adding a positive constant term and a negative contribution which varies in agreement with a Fermi-Dirac distribution function : δE Q(T)mm/sec = 0·288-°. These results are consistent with the existence of localized atom impurity states. The localized state position below the Fermi level, its width, and the density of states at the Fermi level are evaluated. It is found that there are between 5 and 6 d electrons on each iron atom. Similar conclusions can be obtained about electronic properties of iron impurity in other normal hexagonal close-packed host metals (Mg, Zn, Cd), but results are quite different in transition hexagonal close-packed metals (Ci, Ti, Sc, Zr, …) where there do not appear to be any localized electronic states.