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Title: Thermal stability of Li films on polycrystalline molybdenum substrates

Abstract

Lithium (Li) coatings on plasma facing components (PFCs) have been proposed as potential solutions to first wall and divertor challenges in tokamak fusion reactors. We report on the thermal behavior of ultrathin pure Li films deposited on polycrystalline substrates of molybdenum (Mo) and a molybdenum alloy (titanium zirconium molybdenum, TZM). These Li films were studied under controlled ultrahigh vacuum (UHV) conditions and thermal stabilities were primarily compared via temperature programmed desorption (TPD) measurements. In addition, on TZM, which is of particular interest, we obtained additional spectroscopic data using Auger electron spectroscopy (AES) and low energy ion scattering (LEIS) to further characterize the film structure and composition. Here, the monolayer of Li in these films in contact with the substrate is bound much stronger than in bulk Li films, and thermally desorbs at much higher temperatures. Interfacial Li on Mo(poly) has a higher thermal stability than that on TZM(poly), where the limiting values for the desorption activation energies, E d, are 3.56 and 2.84 eV, respectively, in the low coverage, high temperature desorption tail. LEIS indicates some clustering or interdiffusion of the Li films on the TZM substrate at 500 K. No appreciable irreversible absorption of Li occurs on Mo ormore » TZM under the conditions of these experiments.« less

Authors:
 [1]; ORCiD logo [1]
  1. Princeton Univ., NJ (United States)
Publication Date:
Research Org.:
Princeton Univ., NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1571882
Report Number(s):
DOE-PU-0012890-4
Journal ID: ISSN 0022-3115
Grant/Contract Number:  
SC0012890
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 509; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Lithium; Molybdenum; Surface analysis

Citation Formats

Fasoranti, O., and Koel, B. E. Thermal stability of Li films on polycrystalline molybdenum substrates. United States: N. p., 2018. Web. doi:10.1016/j.jnucmat.2018.05.081.
Fasoranti, O., & Koel, B. E. Thermal stability of Li films on polycrystalline molybdenum substrates. United States. doi:10.1016/j.jnucmat.2018.05.081.
Fasoranti, O., and Koel, B. E. Fri . "Thermal stability of Li films on polycrystalline molybdenum substrates". United States. doi:10.1016/j.jnucmat.2018.05.081. https://www.osti.gov/servlets/purl/1571882.
@article{osti_1571882,
title = {Thermal stability of Li films on polycrystalline molybdenum substrates},
author = {Fasoranti, O. and Koel, B. E.},
abstractNote = {Lithium (Li) coatings on plasma facing components (PFCs) have been proposed as potential solutions to first wall and divertor challenges in tokamak fusion reactors. We report on the thermal behavior of ultrathin pure Li films deposited on polycrystalline substrates of molybdenum (Mo) and a molybdenum alloy (titanium zirconium molybdenum, TZM). These Li films were studied under controlled ultrahigh vacuum (UHV) conditions and thermal stabilities were primarily compared via temperature programmed desorption (TPD) measurements. In addition, on TZM, which is of particular interest, we obtained additional spectroscopic data using Auger electron spectroscopy (AES) and low energy ion scattering (LEIS) to further characterize the film structure and composition. Here, the monolayer of Li in these films in contact with the substrate is bound much stronger than in bulk Li films, and thermally desorbs at much higher temperatures. Interfacial Li on Mo(poly) has a higher thermal stability than that on TZM(poly), where the limiting values for the desorption activation energies, Ed, are 3.56 and 2.84 eV, respectively, in the low coverage, high temperature desorption tail. LEIS indicates some clustering or interdiffusion of the Li films on the TZM substrate at 500 K. No appreciable irreversible absorption of Li occurs on Mo or TZM under the conditions of these experiments.},
doi = {10.1016/j.jnucmat.2018.05.081},
journal = {Journal of Nuclear Materials},
number = C,
volume = 509,
place = {United States},
year = {2018},
month = {6}
}

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