Iron enriched peraluminous glasses: Incorporation limit and effect of iron on glass transition temperature and viscosity

This study investigates the effect of iron oxide Fe₂O₃ on the homogeneity, viscosity, and glass transition temperature (Tg) of peraluminous glasses. As-quenched glass samples elaborated at 1350 C show an incorporation limit around 17.5 wt % of Fe₂O₃ (10.4 mol %), while slowly cooled glass samples show a limit of 7.5 wt % of Fe₂O₃ (4.2 mol %). Iron in the peraluminous glasses investigated was detected under three configurations: 6-fold coordinated ⁶Fe³⁺ in majority, 4-fold coordinated ⁴Fe³⁺ and 6-fold coordinated ⁶Fe²⁺. It was observed that Fe₂O₃ addition has a strong fluidifying effect on peraluminous glasses and tends to slightly decrease the glass transition temperature Tg, depending on its thermal history. (authors)