Molecular Structure Of Six Te1-X Glasses And Oxygen Alloying Effects

Raman vibrational modes, Mossbauer Electric Field Gradients and crystallization temperatures exhibit threshold behavior near the composition x=0.20 in binary SixTel_x glasses. This threshold is evidence of a morphological structural change that may be driven by average coordination number. At x.0.20, the glass structure largely consists of Ten chain segments cross-linked by Si atoms and this structure is characteristic of other IV-VI semiconductors. At x Z 0.20, Ten chains reconstruct with tetrahedral Si(Te112)4 units and nucleate a defectridden Si2Te3-like closed packed layer structure which is more metallic in character. Oxygen alloying effects in the semiconducting phase are qualitatively different from those in the metallic phase. The presence of oxygen drastically alters the kinetics of crystallization of the alloy glasses.