Electron spectroscopic study of surface segregation and oxidation of Cu-In and Cu-Au alloys

XPS and AES techniques were employed to study the surface segregation and oxidation of Cu-1at%In alloy. Surface segregation of In has been observed with an enthalpy of segregation of about -34 kJ/mol. The surface oxidation of the Cu-In alloy at 480 K showed first a formation of Cu2O on the alloy surface. The displacement reaction 3Cu2O + 2In → 6Cu + In2O3 occurred on the alloy surface, on further heating of the oxidized surface in vacuum at 700 K. XPS and UPS techniques were employed to study the oxygen interaction with Cu-5at%Au and Cu-11at%Au alloys. At 300 K, oxygen was dissociatively chemisorbed on the Cu sites of the Cu-11% Au alloy surface, and the oxygen desorbed on heating. TDS study showed that desorption follows second order kinetics with an activation energy of desorption of about 75 kJ/mol