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Theoretical Study of Hydroxylated and Dehydroxylated Surfaces of a Cristobalite Model of Silica
The (100) face of β-cristobalite covered by geminal hydroxyls has been taken as a model for the silica surface in order to describe the hydrogen bonding and the condensation of the surface hydroxyls of silica. Periodic Hartree−Fock calculations have been performed for slabs of five atomic layers. Th...
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Published in: | The journal of physical chemistry. B 1997-10, Vol.101 (41), p.8197-8203 |
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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: | The (100) face of β-cristobalite covered by geminal hydroxyls has been taken as a model for the silica surface in order to describe the hydrogen bonding and the condensation of the surface hydroxyls of silica. Periodic Hartree−Fock calculations have been performed for slabs of five atomic layers. The optimized orientation of the hydroxyls corresponds indeed to hydrogen bonds at the surface. As a result, the surface atoms are slightly more negative and the hydroxyls have a specific orientation: one pointing outside the surface plane and the other one directed toward the bulk. The H-bond energy is evaluated to 25 kJ·mol-1. The dehydration, leading to siloxane bridges, is endothermic by ≈200 kJ·mol-1. It must be accompanied by a surface restructuring implicating more than only the first silicon and oxygen layers. |
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ISSN: | 1520-6106 1520-5207 |
DOI: | 10.1021/jp964012b |