Oxygen Affinity: The Missing Link Enabling Prediction of Proton Conductivities in Doped Barium Zirconates

Yoshihiro Yamazaki, Akihide Kuwabara, Junji Hyodo, Yuji Okuyama, Craig A.J. Fisher, Sossina M. Haile

研究成果: Contribution to journalArticle査読

4 被引用数 (Scopus)

抄録

Proton-conducting oxides, specifically doped barium zirconates, have garnered much attention as electrolytes for solid-state electrochemical devices operable at intermediate temperatures (400-600 °C). In chemical terms, hydration energy, Ehyd, and proton-dopant association energy, Eas, are two key parameters that determine whether an oxide exhibits fast proton conduction, but to date ab initio studies have for the most part studied each parameter separately, with no clear correlation with proton conductivity identified in either case. Here, we demonstrate that the oxygen affinity, EO.dopant, defined as the energy released when an oxide ion enters an oxygen vacancy close to a dopant atom, is the missing link between these two parameters and correlates well with experimental proton conductivities in doped barium zirconates. Ab initio calculations of point defects and their complexes in Sc-, In-, Lu-, Er-, Y-, Gd-, and Eu-doped barium zirconates are used to determine Ehyd, Eas, EO.dopant, and the hydrogen affinity, EH.host, of each system. These four energy terms are related by Ehyd = EO.dopant + 2EH.host + 2Eas. Complementary impedance spectroscopy measurements reveal that the stronger the calculated oxygen affinity of a system, the higher the proton conductivity at 350 °C. Although the proton trapping site is also an important factor, the results show that oxygen affinity is an excellent predictor of proton conductivity in these materials.

本文言語英語
ページ(範囲)7292-7300
ページ数9
ジャーナルChemistry of Materials
32
17
DOI
出版ステータス出版済み - 9 8 2020

All Science Journal Classification (ASJC) codes

  • 化学 (全般)
  • 化学工学(全般)
  • 材料化学

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