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

Abstract

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.