Effect of Fe3+ ions on the anionic structure of iron-bearing sodium silicate melts

Abstract

The effects of the coordination of iron ions on the anionic structure of molten iron bearing sodium silicate slags at 1 273 K have been investigated by Raman spectroscopy. The Raman spectra of Na2O-SiO2-FeO-Fe2O3 system equilibrated with various oxygen pressures (pO2) have been measured. The effect of the concentration of iron oxide on the Raman spectra of these systems has also been studied. Under low pO2 conditions (CO2/CO<10), the Raman spectra of Na2O·2SiO2-FeO-Fe2O3 are essentially the same as that of Na2O·2SiO2. However, under high pO2 conditions (CO2/CO>54), a new Raman band of around 900 cm-1 appears and its intensity increases with increase of pO2 and iron oxide content. The scattering intensity at low frequency region (<550 cm-1) also becomes intense with increase of the iron oxide content. It is confirmed that the near 900 cm-1 band can be attributable to the network structure involving Fe3+ ions. Fe3+ ions in the metasilicate melts is found to conjugate the chain units and produce the sheet and monomer units. In the disilicate melts, it will conjugate the sheet units and produce the chain and three-dimensional network units.