Short-Range Disorder in TeO₂ Melt and Glass

Area of Science:

• Materials Science
• Solid State Chemistry
• Amorphous Materials

Background:

• Tellurium dioxide (TeO2) exists in various polymorphs (α, β, γ) with distinct structures.
• Understanding the local atomic arrangements in glassy and molten TeO2 is crucial for predicting material properties.
• Previous studies suggest disorder in TeO2, but detailed structural insights remain limited.

Purpose of the Study:

• To investigate the local structure and coordination environments in molten and glassy TeO2.
• To elucidate the nature of short-range disorder and its temperature dependence.
• To compare the structural characteristics of TeO2 with canonical oxide glass formers.

Main Methods:

• High-resolution X-ray pair distribution function (PDF) analysis.
• Analysis of molten and glassy states of TeO2.
• Comparison with theoretical calculations (ab initio).

Main Results:

• Coordination numbers (nTeO) of approximately 4 were observed in both molten and glassy TeO2.
• Significant short-range disorder was identified, with no clear distinction between bonded and non-bonded interactions.
• A broad distribution of asymmetric Te-O-Te bridges was found, becoming more pronounced with increasing temperature.
• These findings align with Raman spectroscopy data and suggest temperature-induced coordination number reduction.

Conclusions:

• Molten and glassy TeO2 exhibit a distribution of local environments that are temperature-dependent.
• The observed disorder and asymmetric bonding distinguish TeO2 from typical single-oxide glass formers.
• The results are consistent with high-level ab initio cluster calculations, validating the experimental findings.