The influence of NiO on phase separation and crystallization of glasses of the MgO-Al2O3-SiO2-TiO2 system

The evolution of structure and phase composition of NiO-doped titania-containing magnesium aluminosilicate glasses has been studied using small angle X-ray scattering and X-ray diffraction analysis. After initial heat-treatments, three-phase immiscibility develops resulting in precipitation of two amorphous phases. One of them is enriched in MgO, Al2O3 and TiO2, the other in MgO and Al2O3. Nickel oxide enters both phases, which impedes to crystallization of the magnesium aluminotitanates phase; nickel-containing aluminomagnesium regions become centers of further crystallization of aluminomagnesium spinel. The spinel crystallization temperature, as well as mean sizes decreases with increasing the NiO content in the initial glass. (C) 2004 Published by Elsevier B.V.