Structure of TeO₂ Glass and Melt by Reverse Monte Carlo Simulations of High-Energy X-Ray Diffraction Data Sets

Area of Science:

• Materials Science
• Condensed Matter Physics
• Inorganic Chemistry

Background:

• Understanding the atomic structure of tellurium dioxide (TeO2) in both glassy and molten states is essential for predicting its physical and chemical properties.
• Previous studies using High-Energy X-ray Diffraction provided initial structural insights but required further refinement for accurate coordination number determination.

Purpose of the Study:

• To elucidate the short-range and medium-range structural characteristics of TeO2 glass and melt.
• To accurately determine Te-O coordination numbers in both phases by addressing limitations in previous analyses.

Main Methods:

• Utilized Reverse Monte Carlo (RMC) simulations applied to High-Energy X-ray Diffraction data.
• Analyzed Te-O, O-O, and Te-Te pair distribution functions (PDFs) to characterize atomic arrangements.
• Calculated coordination numbers using refined, phase-specific coordination sphere radii.

Main Results:

• Identified a wide distribution of Te-O bond lengths in both TeO2 glass and melt.
• Observed distinct Te-O partial PDFs for the melt, including a peak at 2.35 Å absent in glass.
• Determined accurate Te-O coordination numbers: 3.99 for glass and 3.33 for melt, using appropriate radii (2.41 Å for glass, 2.22 Å for melt).
• Found first peaks in O-O pair distributions around 2.31-2.33 Å and noted greater medium-range disorder in the melt.

Conclusions:

• The structural differences between TeO2 glass and melt, particularly in Te-O bonding and coordination, are significant.
• The RMC simulations provide a more accurate structural model, correcting previous assumptions about coordination sphere radii.
• These findings offer critical insights into the behavior of TeO2 under different phase conditions.