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Proton trapping in yttrium-doped barium zirconate

Yamazaki, Yoshihiro and Blanc, Frédéric and Okuyama, Yuji and Buannic, Lucienne and Lucio-Vega, Juan C. and Grey, Clare P. and Haile, Sossina M. (2013) Proton trapping in yttrium-doped barium zirconate. Nature Materials, 12 (7). pp. 647-651. ISSN 1476-1122.

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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.

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Buannic, Lucienne0000-0003-3055-4058
Haile, Sossina M.0000-0002-5293-6252
Additional Information:© 2013 Macmillan Publishers Limited. Received 10 September 2012; Accepted 28 March 2013; Published online 12 May 2013. This work was supported by the Japan Science Technology Agency, PRESTO and the Gordon and Betty Moore Foundation. Y.O. thanks the JSPS Institutional Program for Young Researcher Overseas Visits. F.B., L.B. and C.P.G. acknowledge financial support from the NSF under grant DMR0804737; F.B. also thanks the EU Marie Curie actions for an International Incoming fellowship 2011-2013 (grant no. 275212) and Clare Hall, University of Cambridge, UK for a Research fellowship. We thank L. Sperrin and B. Y. Zhu for fruitful discussions. Author contributions: Y.Y. designed the experiments, Y.Y. and J.C.L-V. synthesized the samples, Y.O. and Y.Y. performed and analysed the electrochemical and thermogravimetric measurements, Y.Y. and S.M.H. derived the diffusion equations for proton trapping, L.B and Y.Y. performed the NMR measurements, F.B., Y.Y., L.B. and C.P.G. analysed the NMR results, Y.Y., F.B., Y.O., L.B., C.P.G. and S.M.H. discussed the results, and Y.Y., F.B., C.P.G. and S.M.H. co-wrote the manuscript.
Funding AgencyGrant Number
Japan Science Technology AgencyUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
EU Marie Curie Actions International Incoming Fellowship 2011-2013275212
University of Cambridge Research FellowshipUNSPECIFIED
Issue or Number:7
Record Number:CaltechAUTHORS:20130814-134902895
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:39915
Deposited By: Tony Diaz
Deposited On:16 Aug 2013 22:43
Last Modified:09 Mar 2020 13:18

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