The characterization of surface carbides of tungsten

Jay Burton Benziger; E. I. Ko; Robert J. Madix

doi:10.1016/0021-9517(78)90089-1

The characterization of surface carbides of tungsten

Jay Burton Benziger, E. I. Ko, Robert J. Madix

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Abstract

The properties of surface carbides of tungsten single crystals were studied using LEED, AES, and thermal desorption spectroscopy. Carburization of W (100) produced a series of surface structures; at θ = 0.5 a c(2 × 2) structure was observed which compressed into a double row ( 3 -) structure at θ = 0.67. This surface was inert to further carburization below 1000 K. Heating the crystal to 1500 K in ethylene resulted in the formation of an interstitial carbon layer having the structure of ditungsten carbide at the surface. The dissociative adsorption of hydrogen and CO were inhibited by adsorbed carbon or oxygen occupying fourfold symmetry interstitial sites on the W (100) surface. Dissociative adsorption of CO was directly related to the number of pairs of unoccupied fourfold sites. Adsorption of molecular CO correlated with the number of surface sites passivated by adsorbed carbon or oxygen. A surface passivated by dissociatively adsorbed CO was found to behave qualitatively similarly to a carbide surface.

Original language	English (US)
Pages (from-to)	414-425
Number of pages	12
Journal	Journal of Catalysis
Volume	54
Issue number	3
DOIs	https://doi.org/10.1016/0021-9517(78)90089-1
State	Published - Oct 13 1978

All Science Journal Classification (ASJC) codes

Catalysis
Physical and Theoretical Chemistry

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10.1016/0021-9517(78)90089-1

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title = "The characterization of surface carbides of tungsten",

abstract = "The properties of surface carbides of tungsten single crystals were studied using LEED, AES, and thermal desorption spectroscopy. Carburization of W (100) produced a series of surface structures; at θ = 0.5 a c(2 × 2) structure was observed which compressed into a double row ( 3 -) structure at θ = 0.67. This surface was inert to further carburization below 1000 K. Heating the crystal to 1500 K in ethylene resulted in the formation of an interstitial carbon layer having the structure of ditungsten carbide at the surface. The dissociative adsorption of hydrogen and CO were inhibited by adsorbed carbon or oxygen occupying fourfold symmetry interstitial sites on the W (100) surface. Dissociative adsorption of CO was directly related to the number of pairs of unoccupied fourfold sites. Adsorption of molecular CO correlated with the number of surface sites passivated by adsorbed carbon or oxygen. A surface passivated by dissociatively adsorbed CO was found to behave qualitatively similarly to a carbide surface.",

author = "Benziger, {Jay Burton} and Ko, {E. I.} and Madix, {Robert J.}",

note = "Funding Information: The authors gratefully acknowledge the support of the National Science Foundation through the Center for Materials Research at Stanford (NSF-ENG-76-00726). We also wish to express our appreciation for National Science Foundation Equipment Grant NSF-ENG-75-14191, without which this work could not have been accomplished.",

year = "1978",

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doi = "10.1016/0021-9517(78)90089-1",

language = "English (US)",

volume = "54",

pages = "414--425",

journal = "Journal of Catalysis",

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T1 - The characterization of surface carbides of tungsten

AU - Benziger, Jay Burton

AU - Ko, E. I.

AU - Madix, Robert J.

N1 - Funding Information: The authors gratefully acknowledge the support of the National Science Foundation through the Center for Materials Research at Stanford (NSF-ENG-76-00726). We also wish to express our appreciation for National Science Foundation Equipment Grant NSF-ENG-75-14191, without which this work could not have been accomplished.

PY - 1978/10/13

Y1 - 1978/10/13

N2 - The properties of surface carbides of tungsten single crystals were studied using LEED, AES, and thermal desorption spectroscopy. Carburization of W (100) produced a series of surface structures; at θ = 0.5 a c(2 × 2) structure was observed which compressed into a double row ( 3 -) structure at θ = 0.67. This surface was inert to further carburization below 1000 K. Heating the crystal to 1500 K in ethylene resulted in the formation of an interstitial carbon layer having the structure of ditungsten carbide at the surface. The dissociative adsorption of hydrogen and CO were inhibited by adsorbed carbon or oxygen occupying fourfold symmetry interstitial sites on the W (100) surface. Dissociative adsorption of CO was directly related to the number of pairs of unoccupied fourfold sites. Adsorption of molecular CO correlated with the number of surface sites passivated by adsorbed carbon or oxygen. A surface passivated by dissociatively adsorbed CO was found to behave qualitatively similarly to a carbide surface.

AB - The properties of surface carbides of tungsten single crystals were studied using LEED, AES, and thermal desorption spectroscopy. Carburization of W (100) produced a series of surface structures; at θ = 0.5 a c(2 × 2) structure was observed which compressed into a double row ( 3 -) structure at θ = 0.67. This surface was inert to further carburization below 1000 K. Heating the crystal to 1500 K in ethylene resulted in the formation of an interstitial carbon layer having the structure of ditungsten carbide at the surface. The dissociative adsorption of hydrogen and CO were inhibited by adsorbed carbon or oxygen occupying fourfold symmetry interstitial sites on the W (100) surface. Dissociative adsorption of CO was directly related to the number of pairs of unoccupied fourfold sites. Adsorption of molecular CO correlated with the number of surface sites passivated by adsorbed carbon or oxygen. A surface passivated by dissociatively adsorbed CO was found to behave qualitatively similarly to a carbide surface.

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JO - Journal of Catalysis

JF - Journal of Catalysis

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The characterization of surface carbides of tungsten

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