Details
| Original language | English |
|---|---|
| Pages (from-to) | 501-508 |
| Number of pages | 8 |
| Journal | Materials Science- Poland |
| Volume | 23 |
| Issue number | 2 |
| Publication status | Published - 2005 |
Abstract
MgO hydration is an expansive process. It is used in cement to compensate for shrinkage, but it can be harmful at higher concentrations. In this quantum-chemical study, the first steps of the hydration of MgO have been explored. The semiempirical MO method MSINDO with the cyclic cluster model, including long-range electrostatic interactions, has been applied to investigate water adsorption on the (001) surface of MgO. Both molecular adsorption and dissociative adsorption have been found to occur. The latter is stabilized by hydrogen bonding from neighbouring water molecules and surface oxygen. Several energy minima exist for the experimentally low temperature p(3×2) monolayer H2O observed on the MgO (001) surface which consists of a mixture of dissociated and molecular water. One third of the water molecules were dissociated, which is consistent with previous DFT studies. A stable fully hydroxylated MgO (001) surface with OH bridging two Mg ions and the hydrogen bound to the surface oxygen was discovered. This structure appears to promote the expansive, topotactic nucleation of brucite on the MgO (001) surface.
Keywords
- Adsorption, Brucite, Hydration, Magnesium oxide, Water
ASJC Scopus subject areas
- Materials Science(all)
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
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In: Materials Science- Poland, Vol. 23, No. 2, 2005, p. 501-508.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Ceramic hydration with expansion. the structure and reaction of water layers on magnesium oxide. A cyclic cluster study
AU - Heidberg, Bettina
AU - Bredow, Thomas
AU - Littmann, Klaus
AU - Jug, Karl
PY - 2005
Y1 - 2005
N2 - MgO hydration is an expansive process. It is used in cement to compensate for shrinkage, but it can be harmful at higher concentrations. In this quantum-chemical study, the first steps of the hydration of MgO have been explored. The semiempirical MO method MSINDO with the cyclic cluster model, including long-range electrostatic interactions, has been applied to investigate water adsorption on the (001) surface of MgO. Both molecular adsorption and dissociative adsorption have been found to occur. The latter is stabilized by hydrogen bonding from neighbouring water molecules and surface oxygen. Several energy minima exist for the experimentally low temperature p(3×2) monolayer H2O observed on the MgO (001) surface which consists of a mixture of dissociated and molecular water. One third of the water molecules were dissociated, which is consistent with previous DFT studies. A stable fully hydroxylated MgO (001) surface with OH bridging two Mg ions and the hydrogen bound to the surface oxygen was discovered. This structure appears to promote the expansive, topotactic nucleation of brucite on the MgO (001) surface.
AB - MgO hydration is an expansive process. It is used in cement to compensate for shrinkage, but it can be harmful at higher concentrations. In this quantum-chemical study, the first steps of the hydration of MgO have been explored. The semiempirical MO method MSINDO with the cyclic cluster model, including long-range electrostatic interactions, has been applied to investigate water adsorption on the (001) surface of MgO. Both molecular adsorption and dissociative adsorption have been found to occur. The latter is stabilized by hydrogen bonding from neighbouring water molecules and surface oxygen. Several energy minima exist for the experimentally low temperature p(3×2) monolayer H2O observed on the MgO (001) surface which consists of a mixture of dissociated and molecular water. One third of the water molecules were dissociated, which is consistent with previous DFT studies. A stable fully hydroxylated MgO (001) surface with OH bridging two Mg ions and the hydrogen bound to the surface oxygen was discovered. This structure appears to promote the expansive, topotactic nucleation of brucite on the MgO (001) surface.
KW - Adsorption
KW - Brucite
KW - Hydration
KW - Magnesium oxide
KW - Water
UR - http://www.scopus.com/inward/record.url?scp=22944460437&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:22944460437
VL - 23
SP - 501
EP - 508
JO - Materials Science- Poland
JF - Materials Science- Poland
SN - 0137-1339
IS - 2
ER -