Nucleation in As2Se3 glass studied by DSC

Differential scanning calorimetry was used to study nucleation behavior in As2Se3 glass, dependent on particle size. The nucleation process was examined for a series of different coarse powders; the nucleation rate was estimated from the proportion of the crystalline material fraction. The enthalpy of fusion was utilized in this respect, and a correlation between ΔHm and ΔHc was confirmed. Two mechanisms of nucleus formation were found: classical heterogeneous nucleation (following CNT) and so-called “activation” of mechanically-induced defects. The latter appears to represent rapid formation of crystallization centers from a damaged glassy structure, where complete saturation occurs for fine powders in the range of 195-235 °C. A high amount of mechanical defects, on the other hand, was found to partially suppress the CNT nucleation process.