Abstract
Liquid slags composed of Na2O-SiO2-Fe2O3, Na2O-P2O5-Fe2O3, and CaO-SiO2-Al2O3-Fe2O3 have been equilibrated with various oxygen pressures at 1250°C, 950°C, and 1500°C, respectively. After quenching, the glassy solid slag has been polished on the both sides and the optical absorption spectra have been measured with an optical spectrometer.
A strong charge transfer band and five absorption peaks have been observed. The five peaks are inter preted to be due to electron transitions from the ground state of 6A1g to 4T2g (D), 4A1g-4Eg (G), and 4T2g (G)(these three are attributed to 3d electrons of Fe3+) and from the ground state to 5Eg (octahedralsymmetry) and to 5T2g (tetrahedral symmetry);(these two peaks are attributed to 3d electrons of Fe2+).
From the peak positions, it is deduced that oxygen anions are located around a ferric cation in the tetrahedral symmetry in Na2O-SiO2-Fe2O3 slags and in the octahedral symmetry in Na2O-P2O5-Fe2O3 slags and around a ferrous cation in both tetra- and octa-hedral symmetries in the all slags studied.
The position of the edge of the observed charge transfer bands shifted to the lower energy position with the increase of the Fe2O3 addition, oxygen pressure, and the basicity. From the edge shift, it seems that the charge transfer band is essentially due to electron transitions between the ferric cation and oxygen anion.
The reproducibility of the peak position was within 50cm-1 (0.006eV) and the relative error in the molar extinction coefficient was estimated to be ±15%.
