Interaction of oxygen with ZrC(001) and VC(001): Photoemission and first-principles studies

Journal Article · Mon Aug 15 00:00:00 EDT 2005 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.72.075427· OSTI ID:20719343

Rodriguez, J A; Liu, P; Gomes, J; Nakamura, K; Vines, F; Sousa, C; Illas, F ^[1]

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1. Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

High-resolution photoemission and first-principles density-functional calculations were used to study the interaction of oxygen with ZrC(001) and VC(001) surfaces. Atomic oxygen is present on the carbide substrates after small doses of O{sub 2} at room temperature. At 500 K, the oxidation of the surfaces is fast and clear features for ZrO{sub x} or VO{sub x} are seen in the O(1s), Zr(3d), and V(2p{sub 3/2}) core levels spectra, with an increase in the metal/carbon ratio of the samples. A big positive shift (1.3-1.6 eV) was detected for the C 1s core level in O/ZrC(001), indicating the existence of strong O{r_reversible}C or C{r_reversible}C interactions. A phenomenon corroborated by the results of first-principles calculations, which show a CZrZr hollow as the most stable site for the adsorption of O. Furthermore, the calculations also show that a C{r_reversible}O exchange is exothermic on ZrC(001), and the displaced C atoms bond to CZrZr sites. In the O/ZrC(001) interface, the surface C atoms play a major role in determining the behavior of the system. In contrast, the adsorption of oxygen induces very minor changes in the C(1s) spectrum of VC(001). The O{r_reversible}V interactions are stronger than the O{r_reversible}Zr interactions, and O{r_reversible}C interactions do not play a dominant role in the O/VC(001) interface. In this system, C{r_reversible}O exchange is endothermic. VC(001) has a larger density of metal d states near the Fermi level than ZrC(001), but the rate of oxidation of VC(001) is slower. Therefore the O/ZrC(001) and O/VC(001) systems illustrate two different types of pathways for the oxidation of carbide surfaces.

• OSTI ID: 20719343
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 7 Vol. 72; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ADSORPTION
ATOMS
CARBON
CHEMICAL BONDS
D STATES
DENSITY FUNCTIONAL METHOD
EV RANGE
FERMI LEVEL
INTERFACES
METALS
OXIDATION
OXYGEN
PHOTOELECTRON SPECTROSCOPY
PHOTOEMISSION
SUBSTRATES
SURFACES
VANADIUM CARBIDES
ZIRCONIUM CARBIDES