Electrical Conductivity of Novel Tetragonal t′meta-(Ce0.5Zr0.5)O2 Phase Prepared by Reduction and Successive Oxidation of t′ Phase

✍ Scribed by Noriya Izu; Haruo Kishimoto; Takahisa Omata; Shinya Otsuka-Yao-Matsuo

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 194 KB
• Volume: 151
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.8648

✦ Synopsis

A tetragonal t-(Ce 0.5 Zr 0.5 )O 2 , (t), prepared from ceria and zirconia mixtures by a conventional ceramic method, was reduced at 1123 K and successively oxidized at 873 K to attain a novel tetragonal phase, t meta -(Ce 0.5 Zr 0.5 )O 2 (t meta ). The electrical conductivity t of t meta was measured as a function of temperature and time and compared with that for t. The conducting species were also discussed on the basis of the measurements for ionic transference number tN ion . The t for t meta was approximately an order of magnitude higher than that for t, and reproducible as a function of temperature between 973 and 1073 K. At increasing temperatures above 1173 K, the t decreased gradually with time and became consistent with t. The change in t resulted from the fact that a phase transition, t meta Pt, occurred above 1173 K. It was concluded that t meta is a metastable phase with lower thermodynamic stability than that of t; however, it is virtually stable up to around 1143 K. t meta and t are the predominant electronic conductors, possibly because of a hopping mechanism. 2000 Academic Press