Application of a crystallographic index for improvement of the electrolytic properties of the CeO{sub 2}-Sm{sub 2}O{sub 3} system

Journal Article · Wed Dec 01 04:00:00 EST 1999 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1.1392647· OSTI ID:20013024

Mori, Toshiyuki; Ikegami, Takayasu; Yamamura, Hiroshi

Ceria-samaria (CeO{sub 2}-Sm{sub 2}O{sub 3}) is one of the most interesting of fluorite oxides since its oxide ionic conductivity is higher than that of yttria-stabilized zirconia and other CeO{sub 2}-based oxides. In this study, the effective index is proposed to maximize the oxide ionic conductivity in CeO{sub 2}-Sm{sub 2}O{sub 3} based oxides. Considering the crystallographic character of fluorite structure in CeO{sub 2}-Sm{sub 2}O{sub 3} system, the oxygen vacancy level was combined with the ionic radius mismatch between host and dopant cations as criteria for fast ionic conduction. Sm{sub x}Ce{sub 1{minus}x}O{sub 2{minus}{delta}} (0.2 < x < 0.3), (Sm{sub 0.5}Ca{sub 0.5}){sub x}Ce{sub 1{minus}x}O{sub 2{minus}{delta}} (0.175 < x < 0.3), and (Sm{sub 0.936}Cs{sub 0.06}Li{sub 0.004}){sub x}Ce{sub 1{minus}x}O{sub 2{minus}{delta}} (0.2 < x < 0.275) were prepared and characterized as examples with low, intermediate, and high index, respectively. The oxide ionic conductivity increased with an increase of the effective index, confirming the validity of the index. Furthermore, the electrochemical properties of Sm{sub 0.25}Ce{sub 0.75}O{sub 1.88}, (Sm{sub 0.5}Ca{sub 0.5}){sub 0.225}Ce{sub 0.775}O{sub 1.84}, and (Sm{sub 0.936}Cs{sub 0.06}Li{sub 0.004}){sub 0.25}Ce{sub 0.75}O{sub 1.86} were investigated in the temperature range from 700 to 1000 C as representative examples. The oxide ionic conductivity in reducing atmosphere improved with increasing index. It was found that (Sm{sub 0.936}Cs{sub 0.06}Li{sub 0.004}){sub 0.25}Ce{sub 0.75}O{sub 1.86}, with the highest index value in the CeO{sub 2}-Sm{sub 2}O{sub 3} system, exhibited high oxide ionic conductivity and good performance in planar solid-oxide fuel cells.

• Research Organization: National Inst. for Research in Inorganic Materials, Tsukuba, Ibaraki (JP)
• OSTI ID: 20013024
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 12 Vol. 146; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
CERIUM OXIDES
CRYSTALLOGRAPHY
IONIC CONDUCTIVITY
SAMARIUM OXIDES
SOLID OXIDE FUEL CELLS