The values of the thermal heat-capacity changes at the glass transition temperature Tg (ΔCp=Cpl−Cpg) and the values of the apparent activation energy Δh* of the sub Tg relaxation process are determined for GexTe1−x (0.15x0.20) vitreous alloys by means of differential scanning calorimetry investigations. The values of Δh* are then used to determine the values of the fragility index, m. The comparison of these new data to those already obtained on the GexSe1−x vitreous system leads to conclude that both systems exhibit strong thermodynamic character. The stronger thermodynamic character is reached at the Phillips–Thorpe's floppy-to-rigid transition. On the other hand, we find that GexTe1−x exhibits a kinetically fragile character which decreases as the amount of Ge increases in the alloy.

Physica B: Condensed Matter, Volume 304, Issues 1-4, September 2001, Pages 228-236