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Electrical conductivity, magnetism, and optical properties of reduced BaCeO 3
Author(s)
Date Issued
March 1, 2019
Type
Article
Abstract
BaCeO 3 -based perovskites are well-known proton and oxygen ion conductors. For practical applications as electrolytes in solid oxide fuel cells, these compounds must be robust towards reduction of cerium ion. In this work, we explore the effect of reducing atmosphere on the physical properties of undoped and Nb-doped BaCeO 3 . The BaCeO 3 perovskite structure is thermodynamically stable at least up to 1450 ∘ C upon annealing in H 2 -containing atmosphere. Annealing at 1550 ∘ C causes a decomposition of the BaCeO 3 . The higher annealing temperature leads to higher concentration of Ce 3 + ions and a higher electrical conductivity. With increasing the annealing temperature from 1300 to 1450 ∘ C , the activation energy of conductivity decreases from E a = 0.31–0.263 eV. We attribute the electrical conductivity in reduced BaCeO 3 to the activation of the small polaron hopping in agreement with the recent first-principles calculations. However, in contrast to the theoretical predictions, we find no evidence of the Ce 3 + –Ce 3 + spin-singlet small bipolarons.
Citation
Applied Physics A Materials Science and Processing, 125(3), 2019