Microcrystalline Stability and Connectivity Thresholds in (Si,Ge)x(Se, Te)1-x Glasses

The connectivity threshold (predicted by constraint theory 1 to occur at x=0.20) is found experimentally at x+0.23 (2) in GexSe1-x glasses 2 and at x=0.20 (1) in (Si, Ge)x Te1-x glasses. While both experimental thresholds are in good agreement with theory, the agreement is perfect (within experimental uncertainty) in the latter case. This idealized behavior is related to the defect nature of c-SiTe3 which can accommodate short wave-length compositional and mechanical stresses frozen-in during quenching.