Correspondence between electronic polarisability and electron donor power of oxygen for silicate slags containing iron oxides from the perspective of absorption spectra

The applicability of the electronic polarisability of oxygen (α_o) as a measure of the basicity of silicate slags containing iron oxides has been investigated from the perspective of the charge transfer absorption, i.e. the transfer of electrons from O^2- to Fe ³⁺ orbitals, and the redox ratio of (Fe²⁺/Fe ³⁺). Samples used were (i) xNa₂O-(95-x) SiO ₂-5Fe₂O₃ (20<x<50 mol%) and (ii) 30Na₂O-65SiO₂-5Fe₂O₃, for the latter the ratio of Fe²⁺/ Fe³⁺ being varied by melting the samples in a platinum and a graphite crucibles in air. The chemical compositions of the samples were determined by x-ray fluorescence spectroscopy and wet chemical analysis. Densities and refractive indices as well as absorption coefficients were determined at room temperature in order to derive values of α_o from the Lorentz-Lorenz equation. Values of α_o for samples (i) indicate that α_o expresses the electron donor power of oxygen and can be a measure of the basicity of the whole system even in slags containing iron oxides. With respect to samples (ii), it is likely that α_o can be a more reasonable measure of the electron donor power of oxygen or the basicity than the edge of the charge transfer absorption.