Mossbauer and infrared spectroscopy investigation on glass ceramics using red mud

Mossbauer and FTIR spectroscopy as well as XRD were used to study the struc ture and crystallization of glass ceramics using red mud as raw material. T he results indicate that Fe2+ cations are present in both tetrahedral and o ctahedral coordination sites, while Fe2+ cations occupy two structurally di fferent octahedral-like sites. Glasses have interlinked SiO4, ALO(4) and Fe 3+O4 tetrahedra as their fundamental units with K+, Na+, Fe2+ and some Fe3 ions acting as charge balancing cations. With the increase of Fe2O3 conten t, the relative content of Fe2+ and the random state of glass structure inc rease and the absorption bands of FTIR spectra become broad and shift from the high frequency region to lower frequency region. Prolonging nucleation time and increasing crystallization temperature also causes a shift from th e high frequency region to lower frequency regions in the strongest absorpt ion bands. Ca(Fe,Mg)Si2O6 and 2CaO . Al2O3 . SiO2 precipitate as primary an d minor crystalline phases, respectively, in the crystallization processes of glass ceramics. This shortrange order, which is similar to the structure of Ca(Fe,Mg)Si2O6, exists in the glasses and has the precursor structure c apable of producing the primary crystalline phase.