Network Structure in GeS2–Sb2S3 Chalcogenide Glasses: Raman Spectroscopy and Phase Transformation Study

Structural order beyond the next-nearest-neighbor structural units is of great interest in network glasses, especially in chalcogenide glasses, but little specific description can be reached. Here, the structure of pseudobinary (100 – x)GeS2–xSb2S3 chalcogenide glasses is elucidated using differential scanning calorimetry, Raman scattering, and laser-induced phase transformation experiments over its full range (0 ≤ x ≤ 100) of compositions. We observe two compositional thresholds of x = 40 and 50 in the calorimetric experiments, which are confirmed by Raman scattering and laser-induced phase transformation studies, respectively. Three structural features can be derived from these results: the structural motifs in this glass network are the [SbS3] pyramid and [GeS4] tetrahedra, respectively; at x ≥ 40, the connection between [GeS4] tetrahedra vanishes; and at x ≥ 50, the aggregation of four [SbS3] units happens, preparing for the laser-induced crystallization of Sb2S3 crystallites. Combined with valuable indication from the topological thresholds, a specific structural model covering the arrangement of structural units in a large atomic scale is clarified, which can perfectly explain all the experimental results. This work provides a new way to get insight into the intermediate-range order of glass networks and understand their related physical properties.