AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS-TuP

Paper SS-TuP6
Water Dissociation on Boron-Doped Single Crystal Ni@sub3@(Al,Ti) (110) Surface

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: J. Wang, Northwestern University
Authors: J. Wang, Northwestern University
B. Zhou, Northwestern University
Y.W. Chung, Northwestern University
Correspondent: Click to Email
Previous work demonstrated that water dissociates into hydrogen on Ni@sub3@(Al, Ti) (100) surfaces. There is clear evidence that this dissociation reaction results in the reduced ductility of many polycrystalline aluminum-based alloys in a moist environment. Ductility measurements further showed that addition of boron suppresses this moisture-induced embrittlement. To explore the effect of boron on water dissociation, we first dosed the surface of clean Ni@sub3@(Al, Ti) (110) with controlled amounts of boron, using a specially designed low-energy boron ion source, followed by low-temperature exposure to D@sub2@O and temperature-programmed desorption. Results indicated that water dissociates into atomic hydrogen on clean Ni@sub3@(Al, Ti) (110) boron-free surface, which was further verified by x-ray photoemission studies. This dissociation reaction is strongly suppressed by boron adsorption at a coverage of 0.5 monolayer. Auger studies on boron modified surfaces showed that boron is oxidized in this process. The chemical state of water was followed by x-ray photoemission. These studies indicated that addition of boron suppresses water dissociation into atomic hydrogen. By co-adsorption of D@sub2@O and oxygen on boron-modified Ni@sub3@(Al, Ti) (110) surfaces, the effect of oxygen was also investigated by temperature-programmed desorption. The significance of this observation will be discussed.