Proton trapping in yttrium-doped barium zirconate

Yoshihiro Yamazaki*, Frédéric Blanc, Yuji Okuyama, Lucienne Buannic, Juan C. Lucio-Vega, Clare P. Grey, Sossina M. Haile

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

185 Scopus citations

Abstract

The environmental benefits of fuel cells have been increasingly appreciated in recent years. Among candidate electrolytes for solid-oxide fuel cells, yttrium-doped barium zirconate has garnered attention because of its high proton conductivity, particularly in the intermediate-temperature region targeted for cost-effective solid-oxide fuel cell operation, and its excellent chemical stability. However, fundamental questions surrounding the defect chemistry and macroscopic proton transport mechanism of this material remain, especially in regard to the possible role of proton trapping. Here we show, through a combined thermogravimetric and a.c. impedance study, that macroscopic proton transport in yttrium-doped barium zirconate is limited by proton-dopant association (proton trapping). Protons must overcome the association energy, 29 kJ mol -1, as well as the general activation energy, 16 kJ mol -1, to achieve long-range transport. Proton nuclear magnetic resonance studies show the presence of two types of proton environment above room temperature, reflecting differences in proton-dopant configurations. This insight motivates efforts to identify suitable alternative dopants with reduced association energies as a route to higher conductivities.

Original languageEnglish (US)
Pages (from-to)647-651
Number of pages5
JournalNature materials
Volume12
Issue number7
DOIs
StatePublished - Jul 2013

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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