Application of Kramers-Kronig method for analysis Fe-based alloys

摘要

The approach described in the present paper was applied for analysis of Fe-based amorphous and crystallized alloys. All the analyzed specimens have Sw～1. Using classical approach to the Kramers-Kronig transform this value is insufficient for refraction index and therefore optical conductivity determination. The present paper considers new ways of Kramers-Kronig transform accuracy increase by use of high-order quadrature method and new approach to reflectivity extrapolation. Using the advanced described approach a set of amorphous and crystallized alloys of Fe_(80)TM_5B_(15) type was analyzed where TM is the 3d-transition metal. It is shown while adding a small amount of Ti, V or Cr the observed plasma frequency tends to be about 3 to 4 eV higher than in case Mn, Co or Ni impurity was added. The proposed method error of the optical constants determination estimate is not greater than 15% for refraction and absorption indexes and 25% for conductivity even in case experimental spectral range is relatively small. Plasma frequency of analyzed specimens was calculated. The methods of plasma frequency determination were compared. Determination of base points by direct method allows significant accuracy increase and adequate error estimation of this value.