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Improvement of Fluorite Structures in M203-CeO2 (M=Sm, La) System Based on a Novel Effective Index

Published online by Cambridge University Press:  15 February 2011

Toshiyuki Mori ,
Takayasu Ikegami  and
Hiroshi Yamamura
Toshiyuki Mori
Affiliation:
First Research Group, National Institute for Research in Inorganic Materials, 1–1, Namiki, Tsukuba, Ibaraki, 305-0044, Japan, tmori@nirim.go.jp
Takayasu Ikegami
Affiliation:
First Research Group, National Institute for Research in Inorganic Materials, 1–1, Namiki, Tsukuba, Ibaraki, 305-0044, Japan
Hiroshi Yamamura
Affiliation:
Faculty of Engineering, Kanagawa University, 3–27–1, Rokkakubashi, Kanagawa, 221-8686, Japan
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Abstract

M2O3-CeO2(M=Sm, La) system is one of the most interesting of fluorite oxides since the oxide ionic conductivity of it is higher than that of yttria-stabilized zirconia. In this study, the effective index for the improvement of ionic conductivity in CeO2 systems was defined using information regarding ionic radii and the level of oxygen vacancies from the perspective of crystallography. It is assumed that the M2O3 CeO2 based oxides approach the ideal fluorite structure for fast ionic conduction when the effective index increases toward 1. A small amount of alkali- or alkali-earth doped M2O3-CeO2 (M=Sm, La) solid solutions were prepared based on this effective index. The oxide ionic conductivity increased with an increase of this effective index. (La0.75Sr0.2Ba0.05)0.175 Ce0.825 O1.89 that had high effective index, showed high oxide ionic conductivity over the order of magnitude in comparison with 8mol% yttria-stabilized zirconia. Moreover, the oxygen partial pressure dependence of oxide ionic conductivity of M2O3-CeO2(M=Sm, La) solid solutions was improved by the increasing effective index. The utility of this effective index, for improvement of the electrical properties in fluorite CeO2 based materials, was investigated.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 548: Symposia EE – Solid State Ionics V , 1998 , 635
Copyright
Copyright © Materials Research Society 1999

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