Structural and electronic properties of Fe and TiFe from extended and near-edge x-ray-absorption structure

The extended x-ray-absorption fine structure of Fe and TiFe has been measured above the $K$ edges of Fe and Ti at 80 and 300 K. In both materials the fifth and sixth coordination shells show clear evidence of multiple-scattering effects due to the intervening first- and second-shell atoms. The plane-wave approximation for the scattering is found to be inadequate and corrections for the wave curvature are made to the backscattering phase shifts of the first shell. The first peak of the radial distribution function of Fe and TiFe is decomposed into its constituents by means of the beat method. The local order of TiFe around both Ti and Fe atoms is good up to the sixth coordination shell. It is shown that the nearedge structure of both Ti and Fe $K$ edges of TiFe reflects the local state density of $p$-like symmetry at the titanium site, in agreement with detailed partial—density-of-states calculations.