Shift of the Absorption Edge for the Charge Transfer Band in Slags Containing Iron Oxides^*

Abstract

The absorption edge shift for the charge transfer band has been investigated through absorption coefficient measurements on Fe₂O₃-CaO-SiO₂, Fe₂O₃-CaO-SiO₂-Al₂O₃ and Fe₂O₃-Na₂O-SiO₂ slags. The absorption edge was found to move slightly to higher wavelengths with increasing Fe₂O₃ content, but shifted markedly to higher wavelengths with increasing basicity i.e. (%CaO)/(%SiO₂) and (%Na₂O)/(%SiO₂) ratios and Al₂O₃ content. This absorption edge shift has been considered from the viewpoint of the ion refractivity of oxygen and it is proposed that the absorption edge shift is associated with changes of the electron donor power of oxygen ions.