On Structural Rearrangements Near the Glass Transition Temperature in Amorphous Silica

Area of Science:

• Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Amorphous silica (SiO2) exhibits complex behavior near its glass transition temperature (Tg).
• Understanding the structural and dynamic changes during vitrification is crucial.
• The Angell model provides a framework using 'configurons' to describe broken bonds.

Purpose of the Study:

• To analyze cluster formation in topologically disordered amorphous silica.
• To investigate the nature of the glass transition using configuron percolation theory (CPT).
• To compare configuron phase formation with typical second-order phase transformations.

Main Methods:

• Analysis of cluster formation in a disordered network of amorphous silica bonds.
• Application of the Angell model and the concept of configurons.
• Utilizing configuron percolation theory (CPT) and the Kantor-Webman theorem.

Main Results:

• A fractal-dimensional configuron phase was identified in amorphous silica above Tg.
• The glass transition was shown to be analogous to second-order phase transformations.
• The configuron phase formation above Tg differs from typical second-order transformations where the ordered phase is below the threshold.

Conclusions:

• The glass transition in amorphous silica shares similarities with second-order phase transformations.
• Configuron phase formation above Tg is a key characteristic of the glass transition.
• The reversibility of the glass transition differs between heating and cooling processes.