Electronic Conductivity of La-Doped Ceria Ceramics
Abstract:Lanthanum-doped ceria powder with a composition Ce0.8La0.2O1.9 was prepared by heating the oxalate solid solution (Ce0.8La0.2)2(C2O4)3 at 873 K in air. As-prepared powder was densified to 96%–97% relative density by sintering in air at 1773 K for 4 h. The electronic current of the disk sample was measured in a temperature range from 773 to 1113 K by the direct current polarization method using a Hebb–Wagner ion-blocking cell. A linear relationship, which was theoretically predicted, was measured between log e (electronic conductivity) and E (applied voltage) in the applied voltage range of 0.2–1.0 V. The e was proportional to PO2−1/4.3≈PO2−1/4.6 in the oxygen partial pressure range of 10−2–10−8 Pa, and to PO2−1/6.7≈PO2−1/7.1 in the oxygen partial pressure range of 10−7.5–10−22 Pa. The apparent activation energy of the electronic conduction was 1.87–1.94 eV. The hole conduction was also measured in the Po2 range of 102–105 Pa. The transport number of oxide ion was 0.96–1.00 at 773–1113 K under an oxygen partial pressure of 10−5 Pa.
Document Type: Research Article
Affiliations: 1: Department of Advanced Nanostructured Materials Science and Technology, Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan 2: Fuel Cell Group, Energy Electronics Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan
Publication date: August 1, 2005