Synthesis and electrophysical properties of (1−x)Ce0.8Gd0.2O2−δ+xTiO2 (x=0–0.06) solid-state solutions

• Published in: Solid state ionics Vol. 179; no. 27-32; pp. 1557 - 1561
• Main Authors: Pikalova, E.Yu, Maragou, V.I., Demin, A.K., Murashkina, A.A., Tsiakaras, P.E.
• Format: Journal Article
• Language: English
• Published: 30.09.2008
• ISSN: 0167-2738
• DOI: 10.1016/j.ssi.2007.12.086

In the present work the electrical properties of (1 - x)Ce0.8Gd0.2O2 - delta + xTiO2 (x = 0-0.06) synthesized by the standard ceramic technology were investigated, in a wide range of oxygen partial pressures (0.21-10- 20atm at 900 deg C) and temperatures (600-900 deg C), both in air and H2 + 3%H2O atmosphere. It was found, that only the introduction of above 1 mol% TiO2 decreases the sintering temperature of Ce0.8Gd0.2O2 - delta. The values of total electrical conductivity do not change significantly with the content of the sintering aid up to 3 mol%, while the activation energy of total conductivity in air decreases considerably with the introduction of TiO2 into Ce0.8Gd0.2O2 - delta from 87 to 67 kJ/mol; however, it is independent of x up to 0.03. The dependence of the total conductivity on the oxygen partial pressure is characterized by three regions. In the intermediate region (10- 10-10- 14) the conductivity behavior is described according to the oxygen vacancy model. The n-type conductivity region curve of Ce0.8Gd0.2O2 - delta is fitted to a -1/5 slope. The increase of TiO2 content leads to the slope increase at - 1/6, - 1/8 and - 1/9 for 1, 2 and 3 mol% TiO2, respectively, due to the trapping of electrons by Ti4+. 1 mol% doping increases the electrolytic region of Ce0.8Gd0.2O2 - delta from 10- 10 to 10- 13atm. Finally, the optimal content of TiO2 from the viewpoint of sintering and electrical properties was found to be 2 mol%.