Comparative Roles of Al^<3+> and Fe^<3+> lons for Network Construction in Sodium Silicate Melts

概要

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The Raman spectra of Na2O–Al2O3–SiO2 system with different Al2O3contents (up to 25 mol%) and with Na2O/SiO2ratio from 1 to2have been measured at 1 673 K.In the disilicate systems, the Raman spectra do not change significantly with increasing of Al2O3 content except the development of the 500 cm-1 band which is assigned to the three-dimensional network structural unit consisted of Si4+ and Al3+ ions. Also it is found that Al3+ ions possibly interact with monomers and form three-dimensional structures.In the metasilicate systems, intensities of 950 and 850 cm-1 bands gradually decrease while that of 1 100 cm-1 band increases with the increase of Al2O3 content. According to the following equilibrium reaction in the metasilicate composition, -O–Si–O- (chain-like unit)↔Si–O 2-(monomer) + -O–Si–O0 (sheet-like unit)it is confirmed that Al3 ions in the metasilicate systems do not interact with the polymerized silicate anions, such as chain-like or sheet-like structural units. On the other hand, it has a high tendency to interact with SiO44− and construct three-dimensional network units involving Al3+ and Si4+ ions randomly. So it is ob-viousthat the role of Al3+ ions for constructing the network structure is found to be quite different from that of Fe3+.
The Iron and Steel Institute of Japanの論文
2001-05-15