Synthesis and thermal characterization of novel phase change materials (PCMs) of the Se-Te-Sn-Ge (STSG) multi-component system: calorimetric studies of the glass/crystal phase transition.

ABSTRACT

According to recent literature, germanium-containing chalcogenide glasses (ChGs) show improvement in thermal stability and glass-forming ability because of the self-organization of the glass network towards a more rigid structure. The Ge-containing ChGs play a potential role as PCMs in phase-change optical memory (PCOM) applications. This endeavor reports the synthesis of some novel PCMs with Ge as the chemical modifier to improve the kinetic parameters of glass/crystal phase transition. The compositional variation of the various kinetic parameters in the present STSG chalcogen-rich non-oxide glasses Se78-yGeyTe20Sn2 (0 ≤ y ≤ 6) has been studied by means of the state-of-the-art differential scanning calorimetric (DSC) technique in the non-isothermal mode. The thermally assisted glass transition and crystallization phenomena have been investigated by examining the variation in various kinetic parameters like the characteristic kinetic temperatures (glass transition temperature Tg, on-set crystallization temperature To and peak crystallization temperature Tc), the activation energies involved in both phenomena, the thermal stability factor S and the glass-forming ability (GFA). The thermal stability factor S and GFA increase appreciably at higher concentrations of Ge as a signature of stiffness transition followed by the self-organization of the corner-sharing and the edge-sharing arrangements of the GeSe4 phase.