A first principles study on the electronic origins of silver segregation at the Ag-Au (111) surface

The special electronic structure of gold gives rise to many interesting phenomena, such as its color. The surface segregation of the silver-gold system has been the subject of numerous experimental and theoretical studies, yielding conflicting results ranging from strong Ag surface enrichment to Au...

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Bibliographic Details
Published inJournal of applied physics Vol. 122; no. 23
Main Authors Hoppe, Sandra, Müller, Stefan
Format Journal Article
LanguageEnglish
Published Melville American Institute of Physics 21.12.2017
Subjects
Applied physics
Charge transfer
Computer simulation
Density functional theory
Electronegativity
Electronic structure
First principles
Gold
Oxygen enrichment
Silver
Surface layers
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Summary:The special electronic structure of gold gives rise to many interesting phenomena, such as its color. The surface segregation of the silver-gold system has been the subject of numerous experimental and theoretical studies, yielding conflicting results ranging from strong Ag surface enrichment to Au surface segregation. Via a combined approach of density functional theory (DFT) and statistical physics, we have analyzed the segregation at the Ag-Au (111) surface with different Ag bulk concentrations. Interestingly, we observe a moderate Au surface segregation, which is due to a charge transfer from the less electronegative Ag to Au. Canonical Monte Carlo simulations suggest that the calculated concentration profile with a Au-enriched surface layer remains stable up to higher temperatures. However, the presence of adsorbed oxygen reverses the segregation behavior and leads to strong Ag enrichment of the surface layer.
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ISSN:0021-8979
1089-7550
DOI:10.1063/1.5017959