Defect and dopant properties of the SrCeO3-based proton conductor

G C Mather, M S Islam

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Abstract

Atomic-scale studies using advanced simulation techniques have investigated the energetics of defects, oxygen migration, and dopant incorporation in the proton-conducting SrCeO3 system. The interatomic potential model first reproduces the observed distorted perovskite structure of SrCeO3, Substitution with trivalent dopants (M) on the A site in SrCe(Yb)O3-delta (via V-o(..) consumption) is compared with substitution on the B site (via V-o(..) creation); the results support the premise that the absence of ionic conductivity at low doping levels is associated with dopant partitioning over both A and B sites. Dopant-vacancy association is predicted to occur in SrCe0.9M0.1O2.95 for a wide range of M cations. Formation of (M'(Ce)-OHo.) clusters is also calculated to be favorable in accordance with reported proton-trapping effects. The lowest M'(Ce)-OHo. binding energies and the largest M-H distances are found for the most common dopants for proton conductivity in the SrCeO3 system, namely, Y and Yb. The pathway for oxygen migration is proposed as a curved trajectory with an asymmetric energy distribution. The lowest energy redox process is calculated to be oxidation with the formation of holes in accordance with the observation of p-type conductivity at increasing oxygen partial pressures (pO(2)).
LanguageEnglish
Pages1736-1744
Number of pages9
JournalChemistry of Materials
Volume17
Issue number7
DOIs
StatusPublished - 2005

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Protons
Doping (additives)
Defects
Oxygen
Substitution reactions
Proton conductivity
Ionic conductivity
Binding energy
Partial pressure
Perovskite
Vacancies
Cations
Positive ions
Trajectories
Association reactions
Oxidation

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Defect and dopant properties of the SrCeO3-based proton conductor. / Mather, G C; Islam, M S.

In: Chemistry of Materials, Vol. 17, No. 7, 2005, p. 1736-1744.

Research output: Contribution to journalArticle

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abstract = "Atomic-scale studies using advanced simulation techniques have investigated the energetics of defects, oxygen migration, and dopant incorporation in the proton-conducting SrCeO3 system. The interatomic potential model first reproduces the observed distorted perovskite structure of SrCeO3, Substitution with trivalent dopants (M) on the A site in SrCe(Yb)O3-delta (via V-o(..) consumption) is compared with substitution on the B site (via V-o(..) creation); the results support the premise that the absence of ionic conductivity at low doping levels is associated with dopant partitioning over both A and B sites. Dopant-vacancy association is predicted to occur in SrCe0.9M0.1O2.95 for a wide range of M cations. Formation of (M'(Ce)-OHo.) clusters is also calculated to be favorable in accordance with reported proton-trapping effects. The lowest M'(Ce)-OHo. binding energies and the largest M-H distances are found for the most common dopants for proton conductivity in the SrCeO3 system, namely, Y and Yb. The pathway for oxygen migration is proposed as a curved trajectory with an asymmetric energy distribution. The lowest energy redox process is calculated to be oxidation with the formation of holes in accordance with the observation of p-type conductivity at increasing oxygen partial pressures (pO(2)).",
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AU - Islam,M S

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N2 - Atomic-scale studies using advanced simulation techniques have investigated the energetics of defects, oxygen migration, and dopant incorporation in the proton-conducting SrCeO3 system. The interatomic potential model first reproduces the observed distorted perovskite structure of SrCeO3, Substitution with trivalent dopants (M) on the A site in SrCe(Yb)O3-delta (via V-o(..) consumption) is compared with substitution on the B site (via V-o(..) creation); the results support the premise that the absence of ionic conductivity at low doping levels is associated with dopant partitioning over both A and B sites. Dopant-vacancy association is predicted to occur in SrCe0.9M0.1O2.95 for a wide range of M cations. Formation of (M'(Ce)-OHo.) clusters is also calculated to be favorable in accordance with reported proton-trapping effects. The lowest M'(Ce)-OHo. binding energies and the largest M-H distances are found for the most common dopants for proton conductivity in the SrCeO3 system, namely, Y and Yb. The pathway for oxygen migration is proposed as a curved trajectory with an asymmetric energy distribution. The lowest energy redox process is calculated to be oxidation with the formation of holes in accordance with the observation of p-type conductivity at increasing oxygen partial pressures (pO(2)).

AB - Atomic-scale studies using advanced simulation techniques have investigated the energetics of defects, oxygen migration, and dopant incorporation in the proton-conducting SrCeO3 system. The interatomic potential model first reproduces the observed distorted perovskite structure of SrCeO3, Substitution with trivalent dopants (M) on the A site in SrCe(Yb)O3-delta (via V-o(..) consumption) is compared with substitution on the B site (via V-o(..) creation); the results support the premise that the absence of ionic conductivity at low doping levels is associated with dopant partitioning over both A and B sites. Dopant-vacancy association is predicted to occur in SrCe0.9M0.1O2.95 for a wide range of M cations. Formation of (M'(Ce)-OHo.) clusters is also calculated to be favorable in accordance with reported proton-trapping effects. The lowest M'(Ce)-OHo. binding energies and the largest M-H distances are found for the most common dopants for proton conductivity in the SrCeO3 system, namely, Y and Yb. The pathway for oxygen migration is proposed as a curved trajectory with an asymmetric energy distribution. The lowest energy redox process is calculated to be oxidation with the formation of holes in accordance with the observation of p-type conductivity at increasing oxygen partial pressures (pO(2)).

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