2002 Volume 42 Issue 1 Pages 38-43
The FT-IR spectra of the CaO–Al2O3 and CaO–Al2O3–CaF2 slags were measured to understand the structural aspects of (fluoro-) aluminate slags. The infrared spectra of the CaO–Al2O3 slag was interpreted based on the relationship between bond length and force constant of Al–O bond. Thereafter, the role of F- ions in the depolymerization of aluminate network was discussed. The wavenumbers of [AlO4]-tetrahedra higher than that of [AlO6]-octahedra would be originated from the Al–O bond length in tetrahedra shorter than that in octahedra. In the CaOsatd–Al2O3–CaF2 system, the IR-transmitting bands of [AlOnF4-n]-complexes are observed through the entire composition of the fluoroaluminate system, while the bands of [AlO4]-tetrahedra, [AlO6]- and [AlF6]-octahedra appear in the composition less than 24.0 (mol%) CaF2. In the 26.2 (mol%) Al2O3-containing system, the bands of interlinked [AlO4]-tetrahedra are shown at only 2-liquids boundary, while these bands are shown in the whole composition region in the 41.5 (mol%) Al2O3-containing system. In the 41.7 and 51.0(mol%)CaO–Al2O3–CaF2 systems, the transmitting bands of [AlOnF4-n]-complexes are observed through the entire composition, while those of [AlO4]-tetrahedra are shown in the composition of XCaF2/XAl2O3 [lt.gif] 1.0. Also, the relative intensity of the bands indicating [AlO4]-tetrahedra in the 51.0 (mol%) CaO-containing slag is much less than that in the 41.7 (mol%) CaO-containing system.
