Structure, Glass Stability and Crystallization Activation Energy of SrO-CaO-B2O3-SiO2 glasses doped with TiO2

Abstract

By the first time the correlation between glass stability (GS), activation energy for crystallization (Ec) and structural data was investigated for some TiO2doped CaO-SrO-B2O3-SiO2 glasses obtained from the same batch. 11B NMR spectra demonstrated that the boron changes from tetragonal to trigonal configuration for TiO2 contents higher than 4 mol%, while the 29Si NMR spectra showed the absence of Q4 species, in addition to an increase in Q2 at the expense of Q3 units. Both observations are consistent with Ti acting as a network modifier. It was demonstrated that all these glasses crystallize mainly from the surface, and the crystal growth changes with the TiO2 content. Most of the GS parameters increase with the TiO2 content, while Ec decreases for larger TiO2 contents. This dramatic reduction in Ec is strongly correlated to the change in the role of Ti cation in the glass matrix.