X-ray-absorption spectroscopy studies of glassyAs2S3: The role of rapid quenching

We have examined the effect of the thermal quenching rate on the structure of ${\mathrm{As}}_2$ ${\mathrm{S}}_3$ chalcogenide glasses. Structural differences among glasses are discussed on the basis of results of x-ray-absorption measurements. We find that small structural differences are seen among glassy ${\mathrm{As}}_2$ ${\mathrm{S}}_3$ samples bulk quenched from various temperatures between 350 and 800 °C. Comparatively large changes are observed, however, among samples quenched from annealing temperatures between 200 and 300 °C with the structural disorder decreasing with increasing annealing temperature. Material quenched at 300 °C shows a strong tendency toward ordering. Structural differences among samples are discussed in terms of (1) distortions in the As—S—As bond angles between helices and within a helix and (2) deviations of the As apex angles.