Structure of multicomponent SiO2-Al2O3-Fe2O3-CaO-MgO glasses for the preparation of fibrous insulating materials

Spectroscopic investigations in the mid IR region were carried out for all the glasses. This made it possible to determine the influence of thermal treatment on the structural changes of glasses (changes in the spectra shapes). Locations of the bands due to Al-O-Si and Si-O-Si bridges vibrations suggested that in most cases the augite-type phases were present in the systems (aluminium coordination number equal to 4 and 6). Appearance of aluminium in coordination 4 and 6 was confirmed by NMR investigations (two clear bands in the spectra).