Coordination Number Induced Morphological Structural Transition in a Network Glass.

Mossbauer Electric Field Gradients, Raman vibrational modes and crystallization temperatures exhibit threshold behavior near the composition x = 0.20 in binary Si sub x Te sub (1- x) glasses. This threshold is evidence of a morphological structural change that may be driven by network connectivity or average coordination number. At x = 0.20 Te sub n chains reconstruct with tetrahedral Si(Te sub 1/2) sub 4 units and nucleate a defect-ridden Si sub 2 Te sub 3-like layered molecular fragment. These fragments represent the elastically rigid domains that percolate above the threshold.