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Title: Surface oxidation of a Pt--20% CO alloy: An x-ray photoelectron spectroscopy and low-energy electron diffraction study on the (100) and (111) oriented single-crystal surfaces

Abstract

The interaction of oxygen with the surface of a Pt alloy containing approx.20 at. % of cobalt was studied by low-energy electron diffraction (LEED) and x-ray photoelectron spectroscopy (XPS). At this composition, cobalt was found to be randomly substituted in the Pt fcc lattice both in the bulk and at the surface. (111) and 100) oriented single-crystal surfaces as well as polycrystalline surfaces were studied. Dosing these surfaces with oxygen at room temperature at pressures lower than approx.1 x 10/sup -5/ Torr resulted in the formation of a chemisorbed oxygen layer. At temperatures over approx.700 K dosing with oxygen in the same range of pressures led to the formation of a sequence of ordered oxide overlayers. XPS and LEED data showed that the first layer to form was an epitaxial monolayer structurally equivalent to either the (111) or (100) plane of cobalt monoxide (CoO). Under conditions of controlled oxygen dosing, CoO islands of monatomic thickness nucleated and randomly decorated a nearly pure Pt surface. This surface-decoration structure was metastable over a narrow range of oxygen partial pressures and surface temperature. At higher temperatures and pressures, the oxide islands first coalesced, forming a compact monolayer that completely blocked the surface formore » chemisorption, then changed in stoichiometry and structure to form a structural precursor to Co/sub 3/ O/sub 4/.« less

Authors:
; ;
Publication Date:
Research Org.:
Dipartimento di Chimica, Universita di Firenze, 50121 Firenze, Italy
OSTI Identifier:
5312551
Resource Type:
Journal Article
Journal Name:
J. Vac. Sci. Technol., A; (United States)
Additional Journal Information:
Journal Volume: 6:3
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COBALT ALLOYS; OXIDATION; SORPTIVE PROPERTIES; COBALT OXIDES; NUCLEATION; OXYGEN; CHEMISORPTION; PLATINUM BASE ALLOYS; ELECTRON DIFFRACTION; FCC LATTICES; FILMS; HIGH TEMPERATURE; HIGH VACUUM; LAYERS; MONOCRYSTALS; PHOTOELECTRON SPECTROSCOPY; POLYCRYSTALS; STOICHIOMETRY; THICKNESS; THIN FILMS; VERY HIGH TEMPERATURE; X RADIATION; ALLOYS; CHALCOGENIDES; CHEMICAL REACTIONS; COBALT COMPOUNDS; COHERENT SCATTERING; CRYSTAL LATTICES; CRYSTAL STRUCTURE; CRYSTALS; CUBIC LATTICES; DIFFRACTION; DIMENSIONS; ELECTROMAGNETIC RADIATION; ELECTRON SPECTROSCOPY; ELEMENTS; IONIZING RADIATIONS; NONMETALS; OXIDES; OXYGEN COMPOUNDS; PLATINUM ALLOYS; PLATINUM METAL ALLOYS; RADIATIONS; SCATTERING; SEPARATION PROCESSES; SORPTION; SPECTROSCOPY; SURFACE PROPERTIES; TRANSITION ELEMENT COMPOUNDS; 360106* - Metals & Alloys- Radiation Effects

Citation Formats

Bardi, U, Beard, B C, and Ross, P N. Surface oxidation of a Pt--20% CO alloy: An x-ray photoelectron spectroscopy and low-energy electron diffraction study on the (100) and (111) oriented single-crystal surfaces. United States: N. p., 1988. Web. doi:10.1116/1.575149.
Bardi, U, Beard, B C, & Ross, P N. Surface oxidation of a Pt--20% CO alloy: An x-ray photoelectron spectroscopy and low-energy electron diffraction study on the (100) and (111) oriented single-crystal surfaces. United States. doi:10.1116/1.575149.
Bardi, U, Beard, B C, and Ross, P N. Sun . "Surface oxidation of a Pt--20% CO alloy: An x-ray photoelectron spectroscopy and low-energy electron diffraction study on the (100) and (111) oriented single-crystal surfaces". United States. doi:10.1116/1.575149.
@article{osti_5312551,
title = {Surface oxidation of a Pt--20% CO alloy: An x-ray photoelectron spectroscopy and low-energy electron diffraction study on the (100) and (111) oriented single-crystal surfaces},
author = {Bardi, U and Beard, B C and Ross, P N},
abstractNote = {The interaction of oxygen with the surface of a Pt alloy containing approx.20 at. % of cobalt was studied by low-energy electron diffraction (LEED) and x-ray photoelectron spectroscopy (XPS). At this composition, cobalt was found to be randomly substituted in the Pt fcc lattice both in the bulk and at the surface. (111) and 100) oriented single-crystal surfaces as well as polycrystalline surfaces were studied. Dosing these surfaces with oxygen at room temperature at pressures lower than approx.1 x 10/sup -5/ Torr resulted in the formation of a chemisorbed oxygen layer. At temperatures over approx.700 K dosing with oxygen in the same range of pressures led to the formation of a sequence of ordered oxide overlayers. XPS and LEED data showed that the first layer to form was an epitaxial monolayer structurally equivalent to either the (111) or (100) plane of cobalt monoxide (CoO). Under conditions of controlled oxygen dosing, CoO islands of monatomic thickness nucleated and randomly decorated a nearly pure Pt surface. This surface-decoration structure was metastable over a narrow range of oxygen partial pressures and surface temperature. At higher temperatures and pressures, the oxide islands first coalesced, forming a compact monolayer that completely blocked the surface for chemisorption, then changed in stoichiometry and structure to form a structural precursor to Co/sub 3/ O/sub 4/.},
doi = {10.1116/1.575149},
journal = {J. Vac. Sci. Technol., A; (United States)},
number = ,
volume = 6:3,
place = {United States},
year = {1988},
month = {5}
}