| AVS 54th International Symposium | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Poster Session |
| Presenter: | F. Qin, Iowa State University and Ames Laboratory |
| Authors: | F. Qin, Iowa State University and Ames Laboratory J.W. Anderegg, Ames Laboratory C.J. Jenks, Ames Laboratory B. Glesson, Iowa State University D.J. Sordelet, Ames Laboratory P.A. Thiel, Iowa State University and Ames Laboratory |
| Correspondent: | Click to Email |
We have studied the early stage of oxide formation on (111) oriented (Pt, Ni)3Al single crystals in air. From X-ray photoelectron spectroscopy (XPS), the predominant surface oxide changed from NiO to Al2O3, as oxidation temperature increased from 900 to 1300 K. Some NiAl2O4(spinel) also formed at the higher temperatures. Under conditions where NiO and/or NiAl2O4 was present, it resided atop a layer of aluminum oxide, mixed in some cases with metallic Ni. By comparing samples that contained 0, 10 and 20 at. % Pt in the bulk, we found that the effects of Pt were to (1) promote the preferential formation of aluminum oxide over nickel oxide(s) in the top layer at all temperatures studied, (2) suppress the amount of metallic Ni mixed with Al2O3 in the underlying oxide region, (3) reduce the total oxide layer thickness, and (4) sharpen the interface between the oxide and the metallic alloy. The effects of Pt probably arise from a combination of sources: The non-oxidizing nature of Pt relative to Ni or Al; the substitution of Pt for Ni that occurs in the Ni3Al lattice structure; and the increase in Al activity that is induced by Pt.