Thermal behavior of Se-rich GeSb2Se(4-y)Tey (glassy) system

• Thermal behavior of the GeSb2Se(4-y)Tey chalcogenide glasses was studied by DSC.
• Glass transition kinetics was described by the Tool-Narayanaswamy-Moynihan formalism.
• Crystallization kinetics was described in terms of the Johnson-Mehl-Avrami model.
• Glass-forming ability was correlated with the determined P-type heat capacity dependences.

The thermokinetic behavior of the GeSb2Se(4-y)Tey glassy chalcogenide system (a compositional analog of the famous GST-124 PCM material) was thoroughly investigated. Regarding the glass transition kinetics, the substitution of Se by Te was found to lead to looser structural packing resulting in lower activation energy and more independent relaxation movements. On the other hand, in the case of cold crystallization (studied in dependence on particle size) the addition of Te led to the formation of different crystalline phases with higher activation energy of the crystallization process. In addition, based on the description in terms of the Johnson-Mehl-Avrami nucleation-growth kinetics it was found that the Te addition resulted in prioritization of the volume-located 3D crystal growth. Furthermore, P-type heat capacity dependence was found to occur in the present chalcogenide system, where the Te addition led to an increase of the Cp-T curvature in the undercooled liquid. Concerning the overall thermokinetic characterization, the effect of Se↔Te substitution on glass-stability and glass-forming ability was discussed.