Electrolytic properties and nanostructural features in the La2O3-CeO2 system

Toshiyuki Mori, John Drennan, Yarong Wang, Jong Huen Lee, Ji Guang Li, Takayasu Ikegami

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52 Citations (Scopus)

Abstract

Doped ceria (CeO2) compounds are fluorite-type oxides which show oxide ionic conductivity higher than yttria-stabilized zirconia in oxidizing atmosphere. As a consequence of this, considerable interest has been shown in applications of these materials for low or intermediate temperature operation of solid-oxide fuel cells (SOFCs). In this study, the effective index was suggested to maximize the ionic conductivity in La2O3-CeO2 based oxides. The index considers the fluorite structure, and combines the expected oxygen vacancy level with the ionic radius mismatch between host and dopant cations. Using this approach, the ionic conductivity of this system has been optimized and tested under operating conditions of SOFCs. LaxCe1-xO2-δ (x = 0.125, 0.15, 0.175, and 0.20), (LaxSr1-x)0.175Ce0.825 O2-δ (x = 0.1, 0.2, and 0.4), and (La1-xSr0.2Bax)0.175 Ce0.825O2-δ (x = 0.03, 0.05, and 0.07) were prepared and characterized as the specimens with low, intermediate, and high index, respectively. The ionic conductivity was increased with increasing suggested index. The transmission electron microscopy analysis suggested that partial substitution of alkaline earth elements in place of La into Ce site contributes to a decrease of microdomain size and an improvement of conductivity. (La0.75Sr0.2Ba0.05)0.175 Ce0.825O1.891 with high index and small microdomains exhibited the highest conductivity, wide ionic domain, and good performance in SOFCs.

Original languageEnglish
Pages (from-to)A665-A673
JournalJournal of the Electrochemical Society
Volume150
Issue number6
DOIs
Publication statusPublished - 2003 Jul
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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