Electrolytic properties and nanostructural features in the La2O3-CeO2 system

被引:52
作者
Mori, T [1 ]
Drennan, J
Wang, YR
Lee, JH
Li, JG
Ikegami, T
机构
[1] Natl Inst Mat Sci, Ecomat Ctr, Tsukuba 3050044, Japan
[2] Adv Mat Lab, Tsukuba 3050044, Japan
[3] Univ Queensland, Ctr Microscopy & Microanal, Brisbane, Qld 4072, Australia
[4] Seoul Natl Univ, Sch Mat Sci & Engn, Seoul 151742, South Korea
关键词
D O I
10.1149/1.1567265
中图分类号
O646 [电化学、电解、磁化学];
学科分类号
081704 ;
摘要
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-delta (x = 0.125, 0.15, 0.175, and 0.20), (LaxSr1-x)(0.175)Ce0.825O2-delta (x = 0.1, 0.2, and 0.4), and (La1-xSr0.2Bax)(0.175)Ce0.825O2-delta (x 5 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. (C) 2003 The Electrochemical Society.
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页码:A665 / A673
页数:9
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