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Influence of Ce3+ polarons on grain boundary space-charge in proton conducting Y-doped BaCeO3

Abstract

Defect segregation and space-charge formation were investigated for a (0 2 1)[1 0 0] symmetric tilt grain boundary in Y-doped BaCeO3. Density functional theory calculations according to the PBE+U formalism were used to calculate segregation energies for protons, oxygen vacancies and Y-acceptor dopants from the bulk to the grain boundary core. Defect concentration and potential profiles across the grain boundary were obtained from thermodynamic space-charge models. Oxygen vacancies were found to exhibit a particularly exothermic segregation energy of up to −1.66 eV while protons exhibited segregation energies in the range of −0.47 eV to −0.93 eV. The grain boundary was determined to be predominated by protons below 800 K in 3% H2O and the corresponding space-charge potential was 0.4–0.7 V under the Mott–Schottky approximation. The role of electronic defects in the space-charge properties was evaluated, and it was substantiated that electron conduction along the grain boundary could become evident under reducing conditions.
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Category

Academic article

Language

English

Author(s)

Affiliation

  • SINTEF Industry / Sustainable Energy Technology

Year

2018

Published in

Physical Chemistry, Chemical Physics - PCCP

ISSN

1463-9076

Volume

20

Issue

23

Page(s)

16209 - 16215

View this publication at Norwegian Research Information Repository