Berlin 2018 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 38: Metal substrates: Adsorption of atoms and inorganic molecules
O 38.5: Vortrag
Dienstag, 13. März 2018, 15:00–15:15, MA 144
Oxidation of Transition-Metal Surfaces: A Cluster-Expansion Study — •Zhong-Kang Han1, Ray Miyazaki3, Somayeh Farajinafchi1, Santiago Rigamoni2, Maria Troppenz2, Jun-ya Hasegawa3, Sergey V. Levchenko1, and Matthias Scheffler1 — 1Fritz-Haber-Institut der MPG, Berlin 14195, Germany — 2Humboldt–Universität zu Berlin, Berlin 12489, Germany — 3Hokkaido University, Sapporo 001-0021, Japan
Oxidation of metal surfaces plays a fundamental role when functional devices are in contact with an oxidizing environment. The thermodynamics of oxidation and its dependence on the metal type and surface cut are still not fully understood. We study the adsorption of atomic oxygen at Au, Pt, Ni (110), and Rh (100) surfaces, using a cluster-expansion model, parametrized with RPBE calculations. We find that atomic oxygen randomly adsorbs on the short-bridge site of Au(110) or Pt(110) at low coverages (<25%), forming a c(2× 2) pattern as the coverage increases. For coverage >25%, this pattern is destabilized, and a new pattern c(2×√2) will form with top and hollow sites occupied. Interestingly, although O at short-bridge sites is most stable at low coverages, no short-bridge sites are occupied by oxygen at the coverage of 50%. On the contrary, Ni (110) passes through a variety of ordered adsorbed O phases as the coverage is increased, with a mixed occupation of the short-bridge and other sites. Increasing coverage above 75% for Pt (110) or Ni(110), and above 50% for Au(110) or Rh (100) leads to destabilization of dissociative versus molecular adsorption.