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Title: Temporal and thermal evolutions of surface Sr-segregation in pristine and atomic layer deposition modified La 0.6Sr 0.4CoO 3-δ epitaxial films

Abstract

The bulk-to-surface Sr segregation can seriously compromise the stability of oxygen electrocatalysis in La 1-xSr xCoO 3-δ and limit its practical applications such as in solid oxide fuel cells. We show via in situ ambient pressure X-ray photoelectron spectroscopy (APXPS) that the surface Sr-segregation is a kinetically fast process and the equilibrium surface Sr-concentration follows Arrhenius law from 250 to 520 °C at a fixed p O2 = 1 × 10 -3 atm. We also show that application of a nanoscaled, atomic layer deposition (ALD) derived ZrO 2 overcoat can effectively suppress the Sr-segregation by reducing the surface concentration of oxygen vacancies. Electrochemical impedance spectroscopy (EIS) study further confirms that the ALD-ZrO 2-coated LSCo epitaxial film exhibits a much lower and more stable polarization resistance than the uncoated one at 550 °C for >300 hours, suggesting that Sr-segregation is the source of the higher resistance.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [1]
  1. Univ. of South Carolina, Columbia, SC (United States). Dept. of Mechanical Engineering
  2. Univ. of South Carolina, Columbia, SC (United States). Dept. of Mechanical Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Sciences and Technology Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Sciences and Technology Division
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of South Carolina, Columbia, SC (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1491297
Alternate Identifier(s):
OSTI ID: 1482846
Grant/Contract Number:  
AC05-00OR22725; AC02-05CH11231; DMR-1464112
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. A
Additional Journal Information:
Journal Volume: 6; Journal Issue: 47; Journal ID: ISSN 2050-7488
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Wen, Yeting, Yang, Tianrang, Lee, Dongkyu, Lee, Ho Nyung, Crumlin, Ethan J., and Huang, Kevin. Temporal and thermal evolutions of surface Sr-segregation in pristine and atomic layer deposition modified La0.6Sr0.4CoO3-δ epitaxial films. United States: N. p., 2018. Web. doi:10.1039/c8ta08355j.
Wen, Yeting, Yang, Tianrang, Lee, Dongkyu, Lee, Ho Nyung, Crumlin, Ethan J., & Huang, Kevin. Temporal and thermal evolutions of surface Sr-segregation in pristine and atomic layer deposition modified La0.6Sr0.4CoO3-δ epitaxial films. United States. doi:10.1039/c8ta08355j.
Wen, Yeting, Yang, Tianrang, Lee, Dongkyu, Lee, Ho Nyung, Crumlin, Ethan J., and Huang, Kevin. Fri . "Temporal and thermal evolutions of surface Sr-segregation in pristine and atomic layer deposition modified La0.6Sr0.4CoO3-δ epitaxial films". United States. doi:10.1039/c8ta08355j.
@article{osti_1491297,
title = {Temporal and thermal evolutions of surface Sr-segregation in pristine and atomic layer deposition modified La0.6Sr0.4CoO3-δ epitaxial films},
author = {Wen, Yeting and Yang, Tianrang and Lee, Dongkyu and Lee, Ho Nyung and Crumlin, Ethan J. and Huang, Kevin},
abstractNote = {The bulk-to-surface Sr segregation can seriously compromise the stability of oxygen electrocatalysis in La1-xSrxCoO3-δ and limit its practical applications such as in solid oxide fuel cells. We show via in situ ambient pressure X-ray photoelectron spectroscopy (APXPS) that the surface Sr-segregation is a kinetically fast process and the equilibrium surface Sr-concentration follows Arrhenius law from 250 to 520 °C at a fixed pO2 = 1 × 10-3 atm. We also show that application of a nanoscaled, atomic layer deposition (ALD) derived ZrO2 overcoat can effectively suppress the Sr-segregation by reducing the surface concentration of oxygen vacancies. Electrochemical impedance spectroscopy (EIS) study further confirms that the ALD-ZrO2-coated LSCo epitaxial film exhibits a much lower and more stable polarization resistance than the uncoated one at 550 °C for >300 hours, suggesting that Sr-segregation is the source of the higher resistance.},
doi = {10.1039/c8ta08355j},
journal = {Journal of Materials Chemistry. A},
number = 47,
volume = 6,
place = {United States},
year = {2018},
month = {11}
}

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Works referenced in this record:

Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides
journal, September 1976


Enhanced oxygen reduction activity on surface-decorated perovskite thin films for solid oxide fuel cells
journal, January 2011

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  • DOI: 10.1039/c1ee01245b