Initial oxidation stage of CuAu; Protective layer formation

Okada, Michio*; Teraoka, Yuden

It has been found that Cu products containing Au keep their bodies from oxidation. In the oxidation of the CuAu(100) surface, dissociative adsorption of O occurs accompanied by Cu segregation on the surface. No obvious growth of CuO was observed, even for prolonged doses of the 2.3 eV hyperthermal O molecular beam. Thus, it was proposed that surface alloying of Cu-based material with Au works as a perfect protective layer. On the other hand, on the more open (110) surface, additional oxidation-related processes contribute to CuO formation. Although, as on (100), Cu segregation on the (110) surface occurs, the oxidation efficiency is nearly the same for exposure of Cu(110) and CuAu(110) to thermal O. In our recent study for the (111) surface, strong Au segregation to the top layer was found, while on the oxidized surface Cu segregation and formation of the Au rich second (47 at% Au) and third layer (45 at% Au) were found.