Point defect formation and annihilation in silica glass by heat-treatment: Role of water and stress
It was discovered that E′ centers were created by heat-treatment when silica glass contains water and has residual stress. Silica glass samples were heat-treated at 1000 °C for various lengths of time in 355 torr (47 000 Pa) water vapor pressure and dry nitrogen gas atmospheres. The electron paramag...
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Published in: | Journal of non-crystalline solids 2008-03, Vol.354 (14), p.1509-1515 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | It was discovered that
E′ centers were created by heat-treatment when silica glass contains water and has residual stress. Silica glass samples were heat-treated at 1000
°C for various lengths of time in 355
torr (47
000
Pa) water vapor pressure and dry nitrogen gas atmospheres. The electron paramagnetic resonance (EPR) signal of
E′ centers increased initially with heat-treatment time in both atmospheres but then decreased afterwards in the wet atmosphere. It is known that water molecules eliminate paramagnetic defects, such as
E′ centers and non-bridging oxygen hole centers (NBOHCs) by reacting with these defects in the glass, transforming them to non-paramagnetic species such as
Si–OH or
Si–H. The present study indicates that water molecules are also capable of initially creating paramagnetic defects in the glass structure by breaking the silica network structure in the presence of stress. The present observation may be relevant to mechanical strength reduction of silica glasses, which is commonly observed in the presence of water and stress. |
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ISSN: | 0022-3093 1873-4812 |
DOI: | 10.1016/j.jnoncrysol.2007.08.039 |