Structural transitions in liquid Te1−xSex alloys

Polarized and depolarized Raman scattering measurements are reported in liquid ${\mathrm{Te}}_{1\ensuremath{-}x}{\mathrm{Se}}_{x}$ alloys near the melting point. The results provide the first direct evidence for a structural transition within the range $x=0.2\ensuremath{-}0.3$ from a twofold, chainlike bonding to a threefold, pyramidal As-like bonding. Higher-temperature polarized Raman measurements at $x=0.3$ do not indicate a twofold to threefold transition, as has been suggested, but rather indicate increased intrachain disorder.