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- Title
Proton trapping in yttrium-doped barium zirconate.
- Authors
Yamazaki, Yoshihiro; Blanc, Frédéric; Okuyama, Yuji; Buannic, Lucienne; Lucio-Vega, Juan C.; Grey, Clare P.; Haile, Sossina M.
- 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.
- Subjects
PROTON detection; YTTRIUM compounds; DOPING agents (Chemistry); BARIUM zirconate; THERMOGRAVIMETRY; ACTIVATION energy
- Publication
Nature Materials, 2013, Vol 12, Issue 7, p647
- ISSN
1476-1122
- Publication type
Article
- DOI
10.1038/nmat3638