Ceramic hydration with expansion. The structure and reaction of water layers on magnesium oxide. A cyclic cluster study

• Autorzy: Bredow, T. , Heidberg, B. , Littmann, K. , Jug, K.
• Konferencja: E-MRS 2004 Fall Meeting Warsaw, Poland , 6-10 September,2004
• Języki publikacji: EN

Abstrakty

EN

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 x 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.

Słowa kluczowe

EN

magnesium oxide; brucite; water; hydration; adsorption

• Czasopismo: Materials Science Poland
• Rocznik: 2005
• Tom: Vol. 23, No. 2
• Strony: 501--508
• Opis fizyczny: Bibliogr. 26 poz.

Twórcy

autor

Bredow, T.

• Universität Hannover, Fachbereich Chemie, Fachgebiet Theoretische Chemie, Hannover, Germany
• Universität Hannover, Fachbereich Architektur, Fachgebiet für Beschichtungstechnik und Werkstoffchemie, Hannover, Germany

autor

Heidberg, B.

• Universität Hannover, Fachbereich Chemie, Fachgebiet Theoretische Chemie, Hannover, Germany

autor

Littmann, K.

• Universität Hannover, Fachbereich Chemie, Fachgebiet Theoretische Chemie, Hannover, Germany

autor

Jug, K.

• Universität Hannover, Fachbereich Chemie, Fachgebiet Theoretische Chemie, Hannover, Germany

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