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Title: Tailoring low energy electron absorption via surface nano-engineering of cesiated chromium films

Abstract

Here, we demonstrate that improved low energy electron absorption is achieved by suppressing the crystallinity of chromium thin-films grown on W[110], which points to a promising route for achieving highly efficient thermionic energy converters. Using low energy electron microscopy (LEEM) and in situ film growth, we show that substrate temperature control permits well-controlled fabrication of either epitaxial Cr[110] films or nanocrystalline Cr layers. We show that the work function of cesium saturated nanocrystalline Cr thin-films is ~0.20 eV lower than that of epitaxial Cr[110] films. Our LEEM measurements of absorbed and reflected currents as a function of electron energy demonstrate that nanocrystallinity of cesiated chromium films results in 96% electron absorption in the range up to 1 eV above the work function, compared to just 79% absorption in cesiated crystalline Cr[110] films. These results point to metal films with suppressed crystallinity as an economical and scalable means to synthesize nanoengineered surfaces with optimized properties for next generation anode materials in high performance thermionic energy converters.

Authors:
ORCiD logo [1];  [2]; ORCiD logo [1];  [3];  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Spark Thermionics, Inc., Berkeley, CA (United States)
  3. Spark Thermionics, Inc., Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1605692
Alternate Identifier(s):
OSTI ID: 1557025
Grant/Contract Number:  
AC02-05CH11231; AR0000664
Resource Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 115; Journal Issue: 7; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Fernandes Cauduro, Andre L., Hess, Lucas H., Ogletree, D. Frank, Schwede, Jared W., and Schmid, Andreas K. Tailoring low energy electron absorption via surface nano-engineering of cesiated chromium films. United States: N. p., 2019. Web. https://doi.org/10.1063/1.5099115.
Fernandes Cauduro, Andre L., Hess, Lucas H., Ogletree, D. Frank, Schwede, Jared W., & Schmid, Andreas K. Tailoring low energy electron absorption via surface nano-engineering of cesiated chromium films. United States. https://doi.org/10.1063/1.5099115
Fernandes Cauduro, Andre L., Hess, Lucas H., Ogletree, D. Frank, Schwede, Jared W., and Schmid, Andreas K. Tue . "Tailoring low energy electron absorption via surface nano-engineering of cesiated chromium films". United States. https://doi.org/10.1063/1.5099115. https://www.osti.gov/servlets/purl/1605692.
@article{osti_1605692,
title = {Tailoring low energy electron absorption via surface nano-engineering of cesiated chromium films},
author = {Fernandes Cauduro, Andre L. and Hess, Lucas H. and Ogletree, D. Frank and Schwede, Jared W. and Schmid, Andreas K.},
abstractNote = {Here, we demonstrate that improved low energy electron absorption is achieved by suppressing the crystallinity of chromium thin-films grown on W[110], which points to a promising route for achieving highly efficient thermionic energy converters. Using low energy electron microscopy (LEEM) and in situ film growth, we show that substrate temperature control permits well-controlled fabrication of either epitaxial Cr[110] films or nanocrystalline Cr layers. We show that the work function of cesium saturated nanocrystalline Cr thin-films is ~0.20 eV lower than that of epitaxial Cr[110] films. Our LEEM measurements of absorbed and reflected currents as a function of electron energy demonstrate that nanocrystallinity of cesiated chromium films results in 96% electron absorption in the range up to 1 eV above the work function, compared to just 79% absorption in cesiated crystalline Cr[110] films. These results point to metal films with suppressed crystallinity as an economical and scalable means to synthesize nanoengineered surfaces with optimized properties for next generation anode materials in high performance thermionic energy converters.},
doi = {10.1063/1.5099115},
journal = {Applied Physics Letters},
number = 7,
volume = 115,
place = {United States},
year = {2019},
month = {8}
}

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