Structural Evolution of Fused Silica below the Glass-transition Temperature Revealed by In-situ Neutron Total Scattering
| Autor: | Stephen R. Elliott, Bryan R. Wheaton, Dong Ma, Mathieu Bauchy, Albert P. Song, Ying Shi |
|---|---|
| Přispěvatelé: | Apollo - University of Cambridge Repository |
| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
Diffraction Materials science Scattering First sharp diffraction peak 02 engineering and technology Atmospheric temperature range 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Molecular physics Thermal expansion Electronic Optical and Magnetic Materials Rigid-unit mode 0103 physical sciences Materials Chemistry Ceramics and Composites Tetrahedron Neutron In-situ neutron total scattering 0210 nano-technology Glass transition Structure factor Short- and medium-range structure Structural change of fused silica |
| DOI: | 10.17863/cam.46088 |
| Popis: | The common belief that glass structure is completely frozen-in at room temperature is challenged at both macroscopic and atomic scales. Here, we demonstrate an analytical method to elucidate the fine details of a continuous structural change of fused silica (FS) at temperatures below the glass-transition temperature using in-situ neutron total scattering. We find that the SiO4 tetrahedron expands through the entire temperature range with a local coefficient of thermal expansion of 9.1 × 10−6 K−1, while the average medium-range distance, derived from the first sharp diffraction peak of the structure factor, expands at a rate of 21 × 10−6 K−1. Such an expansion difference reflects glass-structure changes within the “rigid-unit mode” model, where each tetrahedron behaves as a rigid unit and the flexible rotations between rigid units lead to more than two times higher medium-range thermal expansion. We further demonstrate that such rotations change the shape of individual rings, leading to a measurable change in the first sharp diffraction peak (FSDP). This study paves the way to measure the structural changes of other silicate glasses, especially through the glass transition. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|