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Title: Effect of Doping on Surface Reactivity and Conduction Mechanism in Sm-doped CeO2 Thin Films

A systematic study by reversible and hysteretic electrochemical strain microscopy (ESM) in samples of Cerium oxide with different Sm content and in several working conditions allows disclosing the microscopic mechanism underlying the difference in electrical conduction mechanism and related surface activity, such as water adsorption and dissociation with subsequent proton liberation. We measure the behavior of the reversible hysteresis loops by changing temperature and humidity, both in standard ESM configuration and using the first order reversal curve method. The measurements have been performed at much lower temperature ranges with respect to alternative measuring techniques. Complementing our study with hard x-ray photoemission spectroscopy and irreversible scanning probe measurements 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 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 electrical conductivity. The defect concentrations determine the type of the prevalent charge carrier in a doping dependent manner.
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [1] ;  [3] ;  [3] ;  [2] ;  [2] ;  [2] ;  [4] ;  [4] ;  [5]
  1. Univ. of Rome Tor Vergata (Italy)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Science and Technology Facilities Council (STFC), Harwell Campus, Oxford (United Kingdom). Diamond Light Source, Ltd.
  4. ORNL
  5. University of Roma Tor Vergata, Italy
Publication Date:
Grant/Contract Number:
AC05-00OR22725; CNMS2014-046
Type:
Accepted Manuscript
Journal Name:
Advanced Functional Materials
Additional Journal Information:
Journal Volume: 8; Journal Issue: 12
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Center for Nanophase Materials Sciences (CNMS); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Sm-doped Ceria; ion conduction; scanning probe microscopy; hard x-ray photoemission; 36 MATERIALS SCIENCE; Sm-doped ceria
OSTI Identifier:
1185545
Alternate Identifier(s):
OSTI ID: 1286788