Crystallization of (GeSe2)0.3(Sb2Se3)0.7 chalcogenide glass - Influence of reaction atmosphere

Abstract

Differential scanning calorimetry, infrared microscopy and X-ray diffraction analysis and were used to investigate the influence of reaction atmosphere (air versus pure nitrogen) on crystallization behavior of (GeSe2)0.3(Sb2Se3)0.7 glass. The presence of oxygen was found to accelerate the crystal growth both on surface and in bulk material, with a similar effect in case of powders and bulk samples. Detailed crystallization kinetics study was performed, revealing that the presence of oxygen leads to a lowered activation energy and steeper onset of the processsingle-curve-averaged masterplot approach was used to deal with the temperature-differentiated complexity of the crystallization. Direct observations by infrared microscopy have shown that the presence of oxygen leads to a formation of robust surface crystalline layer, which prevents powder sintering and bulk samples deformation by viscous flow, and to a more rapid nucleation and crystal growth within the sample volume. Based on the viscosity values estimated for the crystallization temperatures, an explanation for the accelerated volume crystallization was proposed, employing the quasi-stationary conditions contributing to better cohesivity of critical nuclei and crystal/glass interface. The existence of the surface crystalline layer however prevents the sample from reaching full crystallinity.