Effect of Doping on Surface Reactivity and Conduction Mechanism in Sm-doped CeO2 Thin Films
Scanning probe microscopy measurements show irreversible surface electrochemistry in Sm-doped CeO2 thin films, which depends on humidity, temperature and doping concentration. A systematic study by electrochemical strain microscopy (ESM) in samples with two different Sm content and in several working conditions allows disclosing the microscopic mechanism underlying the difference in water adsorption and splitting with subsequent proton liberation. We measure the behavior of the hysteresis loops by changing temperature and humidity, both in standard ESM configuration and using the first order reversal curve (FORC) method. Complementing our study with spectroscopic measurements by hard x-ray photoemission spectroscopy we find that water incorporation is favored until the doping with Sm is too high to allow the presence of Ce3+. The influence of doping on the surface reactivity and conduction mechanism clearly emerges from all of our experimental results. We find that at lower Sm concentration proton conduction is prevalent, featured by lower activation energy and higher mobility. Defect concentrations determine the type of the prevalent charge carrier in a doping dependent manner.
- Univ. of Rome Tor Vergata (Italy)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Science and Technology Facilities Council (STFC), Harwell Campus, Oxford (United Kingdom). Diamond Light Source, Ltd.
- University of Roma Tor Vergata, Italy
- Publication Date:
- OSTI Identifier:
- Grant/Contract Number:
- Accepted Manuscript
- Journal Name:
- Advanced Functional Materials
- Additional Journal Information:
- Journal Volume: 8; Journal Issue: 12
- Research Org:
- Oak Ridge National Laboratory (ORNL); Center for Nanophase Materials Sciences (CNMS)
- Sponsoring Org:
- USDOE Office of Science (SC)
- Country of Publication:
- United States
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY Sm-doped Ceria; ion conduction; scanning probe microscopy; hard x-ray photoemission
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