Shift of the absorption edge for the charge transfer band in slags containing iron oxides

The absorption edge sh ift for the charge tra nsf er 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.