Non-isothermal crystallization of (GeS2)0.1(Sb2S3)0.9 chalcogenide glass: Influence of reaction atmosphere

• Influence of reaction atmosphere on crystallization of (GeS2)0.1(Sb2S3)0.9 glass was studied.
• Presence of oxygen accelerates crystal growth from mechanically induced defects.
• Formal kinetic description is similar for crystallization in air and in nitrogen.
• Presence of oxygen partially inhibits powder sintering above glass transition.

Differential scanning calorimetry, X-ray diffraction analysis and infrared microscopy were used to investigate the influence of reaction atmosphere (air versus pure nitrogen) on crystallization behavior of (GeS2)0.1(Sb2S3)0.9 powdered and bulk glass. The presence of oxygen was found to accelerate (in comparison to pure N2) the crystallization process in dependence on particle size of the powdered glass. Large amounts of mechanically induced defects (and not the increased surface area) were found to be the key catalyzing factor. Formal kinetic description of the crystallization mechanism (presented in terms of the nucleation-growth model) remained unchanged by the presence of oxygen. In addition, also the crystallographic nature of the crystalline products was similar for crystallization in air and in pure N2. Direct observations by infrared microscopy confirmed that the (GeS2)0.1(Sb2S3)0.9 glass crystallizes from surface. These observations also evidenced similar morphology of the crystallites growing in and without presence of oxygen, as well as the more preferential defects-based growth in case of the oxygenated samples. In addition, presence of oxygen was found to partially inhibit the powder sintering above the glass transition temperature.