Hydrogen release in SiO2: Source sites and release mechanisms

We investigate molecular scale mechanisms for radiation-induced release of hydrogen from precursor sites using density functional theory applied to a fully periodic model of SiO2. We focus on proton release from H-decorated oxygen vacancies in the bulk oxide. After hole-capture at the vacancy, a pro...

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Bibliographic Details
Published in:Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 2006-09, Vol.250 (1-2), p.274-278
Main Authors: Van Ginhoven, R.M., Hjalmarson, H.P., Edwards, A.H., Tuttle, B.R.
Format: Article
Language:English
Subjects:
Amorphous silica
DFT
Hydrogen
Radiation effects
Silicon dioxide
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Summary:We investigate molecular scale mechanisms for radiation-induced release of hydrogen from precursor sites using density functional theory applied to a fully periodic model of SiO2. We focus on proton release from H-decorated oxygen vacancies in the bulk oxide. After hole-capture at the vacancy, a proton can hop to an energetically favorable bound state at a neighboring oxygen atom. In α-quartz, this release mechanism has an activation energy of about 1.2eV. In amorphous silica, this hop has a range of low barriers, from 0.1 to 0.5eV. Furthermore, another proton release mechanism involves cracking of H2 molecules by a reaction with an isolated, positively charged Si-dangling bond.
ISSN:0168-583X
1872-9584
DOI:10.1016/j.nimb.2006.04.123