Study of correlations between glass-transition temperature and local structure of Ge-As-Se, Ge-As-Se-S chalcogenide glasses

ABSTRACT

The local structure and glass transition of Ge-As-Se, Ge-As-Se-Schalcogenide glasses have been studied by X-ray diffraction and differential scanning calorimetry. By applying the theory of topological constraints and considering chemically ordered network models, it has been determined that Ge₁₀As₂₀S₁₀Se₆₀ (average coordination number $⟨r⟩$ = 2.4), Ge₂₅As₁₀S₂₅Se₄₀ ($⟨r⟩$ = 2.6) are the compositions associated with the more stable glasses. This result is related to the larger differences between the glass transition (T_g) and crystallization-transition (T_cr) temperatures (ΔT_g-cr∼ 38 and 43 K) at these compositions. Relatively high values of short-range (d∼5.7–6.34 Å) and medium-range (L∼26.59–33.74 Å) order parameters of the local structure in the glass compositions satisfying the mentioned conditions affect the glass-transition temperature (T_g) and cause its value to increase (T_g∼589–689 K). As a result of comparative analyses of X-ray diffraction and differential scanning calorimetry curves it has been determined that there is a correlation between the glass-transition temperature (T_g) with the short range (d) and medium range order (L) parameters of the local structure.

KEYWORDS:

• Chalcogenide glasses
• amorphous
• non-crystalline
• medium-range order
• short-range order
• DSC
• XRD
• glass transition

Disclosure statement

No potential conflict of interest was reported by the author(s).