Experimental Nonevidence of Fragile-to-Strong Crossover.

Area of Science:

• Materials Science
• Solid State Chemistry
• Glass Science

Background:

• Chalcogenide glasses, particularly Ge-Se systems, are technologically important.
• Understanding their viscosity is crucial for processing and applications.
• The presence or absence of a fragile-to-strong crossover impacts glass properties.

Purpose of the Study:

• To investigate the viscosity behavior of Ge-Se glass-forming systems.
• To determine if a fragile-to-strong crossover occurs in these compositions.
• To characterize the flow properties of Ge-Se glasses with varying germanium content.

Main Methods:

• Synthesized four Ge-Se glass compositions with 5-20 at.% Ge.
• Measured viscosity over ~13 orders of magnitude.
• Combined pressure-assisted melt filling with penetration and parallel-plate viscometry.

Main Results:

• Viscosity measurements covered an extensive dynamic range.
• No fragile-to-strong crossover was observed in any of the studied Ge-Se compositions.
• The viscosity behavior is consistent across the examined compositional range.

Conclusions:

• The Ge-Se glass system does not exhibit a fragile-to-strong crossover.
• Viscosity measurements confirm the unique flow behavior of these chalcogenide glasses.
• Further research can explore the implications for material processing and device fabrication.