Double perovskite cathodes for proton-conducting ceramic fuel cells: are they triple mixed ionic electronic conductors?

Helena Téllez Lozano, John Druce, Samuel J. Cooper, John A. Kilner

    Research output: Contribution to journalArticlepeer-review

    22 Citations (Scopus)

    Abstract

    18O and 2H diffusion has been investigated at a temperature of 300 °C in the double perovskite material PrBaCo2O5+δ (PBCO) in flowing air containing 200 mbar of 2H2 16O. Secondary ion mass spectrometry (SIMS) depth profiling of exchanged ceramics has shown PBCO still retains significant oxygen diffusivity (~1.3 × 10−11 cm2s−1) at this temperature and that the presence of water (2H2 16O), gives rise to an enhancement of the surface exchange rate over that in pure oxygen by a factor of ~3. The 2H distribution, as inferred from the 2H2 16O SIMS signal, shows an apparent depth profile which could be interpreted as 2H diffusion. However, examination of the 3-D distribution of the signal shows it to be nonhomogeneous and probably related to the presence of hydrated layers in the interior walls of pores and is not due to proton diffusion. This suggests that PBCO acts mainly as an oxygen ion mixed conductor when used in PCFC devices, although the presence of a small amount of protonic conductivity cannot be discounted in these materials.

    Original languageEnglish
    Pages (from-to)977-986
    Number of pages10
    JournalScience and Technology of Advanced Materials
    Volume18
    Issue number1
    DOIs
    Publication statusPublished - Dec 31 2017

    All Science Journal Classification (ASJC) codes

    • Materials Science(all)

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