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

# metadata.dc.description.abstract[].value
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
2
 at room temperature. At 
500
K
, the oxidation of the surfaces is fast and clear features for 
Zr
O
x
 or 
V
O
x
 are seen in the 
O
(
1
s
)
, 
Zr
(
3
d
)
, and 
V
(
2
p
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 
1
s
 core level in 
O
∕
Zr
C
(
001
)
, indicating the existence of strong 
O
↔
C
 or 
C
↔
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
↔
O
 exchange is exothermic on ZrC(001), and the displaced C atoms bond to CZrZr sites. In the 
O
∕
Zr
C
(
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
(
1
s
)
 spectrum of VC(001). The 
O
↔
V
 interactions are stronger than the 
O
↔
Zr
 interactions, and 
O
↔
C
 interactions do not play a dominant role in the 
O
∕
V
C
(
001
)
 interface. In this system, 
C
↔
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
∕
Zr
C
(
001
)
 and 
O
∕
V
C
(
001
)
 systems illustrate two different types of pathways for the oxidation of carbide surfaces.

# metadata.dc.relation.isformatof[].value
Reproducció digital del document publicat en format paper, proporcionada per PROLA i http://dx.doi.org/10.1103/PhysRevB.72.075427

# metadata.dc.source[].value
Articles publicats en revistes (Ciència dels Materials i Química Física)

# metadata.dc.title[].value
Interaction of oxygen with ZrC(001) and VC(001): Photoemission and first-principles studies