The role of trivalent element oxides in CaO (Na2O)-M2O3-SiO2 glasses from T-g

In this paper T-g values of calcium (sodium) silicate glasses containing ad ded with oxides of trivalent elements are reported. The plots of T-g as a f unction of composition or vs. the ionic field strength prove to be useful i n discussing the role of the oxides in the glass structure. It is found tha t, at least in the studied composition range, Sc2O3, Y2O3, La2O3, and In2O3 , behave as network modifier oxides. In the compositional ranges studied, the hypothesis based on them well agre e with the expectations based on the known criteria reported in literature and on FTIR spectra.