X-ray scattering studies of the short and medium range ordering in AsxTe1−x glasses

The structures of As_xTe_1−x(x = 0.2, 0.4, and 0.5) glasses are studied using the differential X-ray anomalous scattering technique. The partial distribution functions have also been obtained for the stoichiometric As₂Te₃ glass, giving information on the medium range ordering. All the glasses show chemical disorder to differing extents, the As₂Te₃ glass being the most disordered. The Te coordination number undergoes a change at x=0.4 where it is 2.5 compared with 2 for AsTe. This change indicates the existence of about 50% of threefold Te sites in the stoichiometric glass, as well as in the Te-rich glasses. Some of the physical properties of the glasses may be explained based on these results.