Surface segregation in alloys: LEED, Auger, and gas adsorption study of segregation of Au to the (111) surface of Ni
Abstract
The (111) surface of Ni single crystals containing less than 1% Au was studied using Auger spectroscopy, LEED, and gas adsorption. The heat of segregation of gold to the Ni(111) surface, obtained from equilibrium measurements of the surface composition as a function of temperature, was found to be 12±2 kcal/mole. This result is not temperature, was found to be 12±2 kcal/mole. This result is not adequately described by existing theories of surface segregation. We also observed a variety of other complex phenomena. For gold surface concentrations above about 50%, an ordered overlayer of gold formed on the nickel substrate. Exposure of a partially gold covered surface to oxygen causes the disappearance of the gold. Small amounts of gold on the surface effectively poison it for adsorption of CO.
- Publication:
-
Journal of Chemical Physics
- Pub Date:
- August 1976
- DOI:
- 10.1063/1.433171
- Bibcode:
- 1976JChPh..65.1089B
- Keywords:
-
- 79.20.Fv;
- 68.20.Dy;
- 73.20.Hb;
- Electron impact: Auger emission;
- Impurity and defect levels;
- energy states of adsorbed species