Physical aging of arsenic trisulfide thick films and bulk materials

Differential scanning calorimetry (DSC) measurements were performed at different heating rates under nonisothermal conditions to probe the glass transition kinetics of As₂S₃ bulk glass and thick films. We found that, for films, the glass transition temperature (T_g) increases with increasing annealing temperature, and sharp crystalline-like melting endothermic peaks appear in samples annealed at 160°C. Such sharp endothermic peaks could also be found for samples annealed at 140°C for 300 h, indicating a very slow crystallization process. The activation energy for the molecular motions and rearrangements around T_g could be estimated as 2.12 eV for films and 2.3 eV for the bulk, respectively.