Relaxation processes of densified silica glass
Abstract
Densified SiO2 glasses, obtained from different pressure and temperature routes, have been annealed over a wide range of temperatures far below the glass transition temperature (500 °C-900 °C). Hot and cold compressions were useful to separate the effects of pressure and the compression temperature. In situ micro-Raman spectroscopy was used to follow the structural evolution during the thermal relaxation. A similar glass structure between the non-densified silica and the recovered densified silica after the temperature annealing demonstrates a perfect recovery of the non-densified silica glass structure. While the density decreases monotonically, the structural relaxation takes place through a more complex mechanism, which shows that density is not a sufficient parameter to fully characterize the structure of densified silica glass. The relaxation takes place through a transitory state, consisting in an increase of the network inhomogeneity, shown by an increase in the intensity of the D2 band which is associated with 3 membered rings. The activation energy of these processes is 255 ± 45 kJ/mol for the hot compressed samples. The kinetic is overall faster for the cold compressed samples. In that last case, the relaxation is partially activated by internal stresses release.
- Publication:
-
Journal of Chemical Physics
- Pub Date:
- March 2017
- DOI:
- 10.1063/1.4977036
- arXiv:
- arXiv:2402.05315
- Bibcode:
- 2017JChPh.146i4504C
- Keywords:
-
- Physics - Chemical Physics;
- Condensed Matter - Materials Science
- E-Print:
- J. Chem. Phys. 7 March 2017