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VOLUME 85, NUMBER 3 P H Y S I C A L R E V I E W L E T T E R S 17 JULY 2000 Surface Stoichiometry and the Initial Oxidation of NiAl(110)
 

Summary: VOLUME 85, NUMBER 3 P H Y S I C A L R E V I E W L E T T E R S 17 JULY 2000
Surface Stoichiometry and the Initial Oxidation of NiAl(110)
Alexander Y. Lozovoi, Ali Alavi, and Michael W. Finnis
Atomistic Simulation Group, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN, United Kingdom
(Received 21 March 2000)
Selective oxidation of the surface of an ordered alloy requires redistribution of the atomic species in
the vicinity of the surface. This process can be understood in terms of the formation and movements of
point defects in the compound. On the basis of ab initio density-functional calculation we found both the
creation of exchange defects near the NiAl surface and segregation of Ni vacancies to the top layer to be
extremely favorable in the presence of oxygen. Scenarios for the initial oxidation of NiAl are suggested
which demonstrate the appearance of an additional energy barrier on the Ni-rich side compared to the
Al-rich side. The expulsion of Ni from the oxide layer as it forms is the driving force for its stability.
PACS numbers: 68.35.Md, 68.35.Dv, 71.20.Lp, 81.15.Aa
The oxidation of metal surfaces is relevant to many
fields in which the metal-oxide interface occurs, including
heterogeneous catalysis and corrosion. Understanding the
microscopic processes which govern the initial stages of
oxidation has been the focus of much research recently,
using both experimental and theoretical ab initio tech-
niques. The oxidation of pure metal surfaces such as

  

Source: Alavi, Ali - Department of Chemistry, University of Cambridge

 

Collections: Chemistry