Temporal and thermal evolutions of surface Sr-segregation in pristine and atomic layer deposition modified La0.6Sr0.4CoO3-δ epitaxial films
- Univ. of South Carolina, Columbia, SC (United States). Dept. of Mechanical Engineering
- 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
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Sciences and Technology Division
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source
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.
- Research Organization:
- 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 Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF) (United States)
- Grant/Contract Number:
- AC05-00OR22725; AC02-05CH11231
- OSTI ID:
- 1491297
- Alternate ID(s):
- OSTI ID: 1656484; OSTI ID: 1482846
- Journal Information:
- Journal of Materials Chemistry. A, Journal Name: Journal of Materials Chemistry. A Journal Issue: 47 Vol. 6; ISSN 2050-7488
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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Nanostructured Materials and Interfaces for Advanced Ionic Electronic Conducting Oxides
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