The dipole model at the atomic scale: Explaining variations in work function due to configurational and compositional changes in Ba/Sc/O adsorbates on W (001), (110), and (112)

Matthew J. Beck; Qunfei Zhou; Xiaotao Liu; Tyler Maxwell; Bernard Vancil; T. John Balk

doi:10.1109/IVEC.2018.8391543

The dipole model at the atomic scale: Explaining variations in work function due to configurational and compositional changes in Ba/Sc/O adsorbates on W (001), (110), and (112)

Matthew J. Beck, Qunfei Zhou, Xiaotao Liu, Tyler Maxwell, Bernard Vancil, T. John Balk

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

Abstract

The adsorption of alkaline-earth metals (and/or their oxides) on transition metal surfaces reduces the work function significantly, an effect that has been widely applied in thermionic dispenser cathodes to improve electron emission. Even slight changes in adsorbate composition and configuration on the emitting surface can lead to remarkable differences in work function. In this work, atomistic calculations of the structure, work function, and stability of a range of Ba/Sc/O-adsorbed W surfaces relevant to scandate cathodes are used to develop an atomic-scale understanding of the mechanisms leading to changes in work function. While a range of theoretical explanations have been put forward to explain how alkaline-earth ions or oxide layers modify the work function, the present results strongly support the idea that surface dipole effects are the critical mechanism controlling work function changes. These results provide signifiant insight into efforts to design new and novel low-work function surfaces and materials.

Original language	English
Title of host publication	2018 IEEE International Vacuum Electronics Conference, IVEC 2018
Pages	43-44
Number of pages	2
ISBN (Electronic)	9781538604540
DOIs	https://doi.org/10.1109/IVEC.2018.8391543
State	Published - Jun 20 2018
Event	19th IEEE International Vacuum Electronics Conference, IVEC 2018 - Monterey, United States Duration: Apr 23 2018 → Apr 26 2018

Publication series

Name	2018 IEEE International Vacuum Electronics Conference, IVEC 2018

Conference

Conference	19th IEEE International Vacuum Electronics Conference, IVEC 2018
Country/Territory	United States
City	Monterey
Period	4/23/18 → 4/26/18

Bibliographical note

Publisher Copyright:
© 2018 IEEE.

Funding

This work was financially supported by the Defense Advanced Research Projects Agency (DARPA) Innovative Vacuum Electronics Science and Technology (INVEST) program, under grant number N66001-16-1-4041. The views, opinions, and/or findings expressed are those of the author(s) and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government.

Funders	Funder number
Innovative Vacuum Electronics Science and Technology	N66001-16-1-4041
Defense Advanced Research Projects Agency

Keywords

dipole moment
electro-static potential
surface structure
thermionic cathode
work function

ASJC Scopus subject areas

Electrical and Electronic Engineering
Instrumentation

Access to Document

10.1109/IVEC.2018.8391543

Cite this

Beck, M. J., Zhou, Q., Liu, X., Maxwell, T., Vancil, B., & Balk, T. J. (2018). The dipole model at the atomic scale: Explaining variations in work function due to configurational and compositional changes in Ba/Sc/O adsorbates on W (001), (110), and (112). In 2018 IEEE International Vacuum Electronics Conference, IVEC 2018 (pp. 43-44). (2018 IEEE International Vacuum Electronics Conference, IVEC 2018). https://doi.org/10.1109/IVEC.2018.8391543

Beck, Matthew J. ; Zhou, Qunfei ; Liu, Xiaotao et al. / The dipole model at the atomic scale : Explaining variations in work function due to configurational and compositional changes in Ba/Sc/O adsorbates on W (001), (110), and (112). 2018 IEEE International Vacuum Electronics Conference, IVEC 2018. 2018. pp. 43-44 (2018 IEEE International Vacuum Electronics Conference, IVEC 2018).

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title = "The dipole model at the atomic scale: Explaining variations in work function due to configurational and compositional changes in Ba/Sc/O adsorbates on W (001), (110), and (112)",

abstract = "The adsorption of alkaline-earth metals (and/or their oxides) on transition metal surfaces reduces the work function significantly, an effect that has been widely applied in thermionic dispenser cathodes to improve electron emission. Even slight changes in adsorbate composition and configuration on the emitting surface can lead to remarkable differences in work function. In this work, atomistic calculations of the structure, work function, and stability of a range of Ba/Sc/O-adsorbed W surfaces relevant to scandate cathodes are used to develop an atomic-scale understanding of the mechanisms leading to changes in work function. While a range of theoretical explanations have been put forward to explain how alkaline-earth ions or oxide layers modify the work function, the present results strongly support the idea that surface dipole effects are the critical mechanism controlling work function changes. These results provide signifiant insight into efforts to design new and novel low-work function surfaces and materials.",

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Beck, MJ, Zhou, Q, Liu, X, Maxwell, T, Vancil, B & Balk, TJ 2018, The dipole model at the atomic scale: Explaining variations in work function due to configurational and compositional changes in Ba/Sc/O adsorbates on W (001), (110), and (112). in 2018 IEEE International Vacuum Electronics Conference, IVEC 2018. 2018 IEEE International Vacuum Electronics Conference, IVEC 2018, pp. 43-44, 19th IEEE International Vacuum Electronics Conference, IVEC 2018, Monterey, United States, 4/23/18. https://doi.org/10.1109/IVEC.2018.8391543

The dipole model at the atomic scale: Explaining variations in work function due to configurational and compositional changes in Ba/Sc/O adsorbates on W (001), (110), and (112). / Beck, Matthew J.; Zhou, Qunfei; Liu, Xiaotao et al.
2018 IEEE International Vacuum Electronics Conference, IVEC 2018. 2018. p. 43-44 (2018 IEEE International Vacuum Electronics Conference, IVEC 2018).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

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AB - The adsorption of alkaline-earth metals (and/or their oxides) on transition metal surfaces reduces the work function significantly, an effect that has been widely applied in thermionic dispenser cathodes to improve electron emission. Even slight changes in adsorbate composition and configuration on the emitting surface can lead to remarkable differences in work function. In this work, atomistic calculations of the structure, work function, and stability of a range of Ba/Sc/O-adsorbed W surfaces relevant to scandate cathodes are used to develop an atomic-scale understanding of the mechanisms leading to changes in work function. While a range of theoretical explanations have been put forward to explain how alkaline-earth ions or oxide layers modify the work function, the present results strongly support the idea that surface dipole effects are the critical mechanism controlling work function changes. These results provide signifiant insight into efforts to design new and novel low-work function surfaces and materials.

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Beck MJ, Zhou Q, Liu X, Maxwell T, Vancil B, Balk TJ. The dipole model at the atomic scale: Explaining variations in work function due to configurational and compositional changes in Ba/Sc/O adsorbates on W (001), (110), and (112). In 2018 IEEE International Vacuum Electronics Conference, IVEC 2018. 2018. p. 43-44. (2018 IEEE International Vacuum Electronics Conference, IVEC 2018). doi: 10.1109/IVEC.2018.8391543

The dipole model at the atomic scale: Explaining variations in work function due to configurational and compositional changes in Ba/Sc/O adsorbates on W (001), (110), and (112)

Abstract

Publication series

Conference

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

Access to Document

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