Electronic conductivity of ZrO2-CeO2-YO1.5 solid solutions

The temperature and the oxygen partial pressure dependencies of the electro nic conductivity of [(ZrO2)(1-x)(CeO2)(x)](0.8)(YO1.5)(0.2) (x = 0-1, 0.1 s tep) solid solutions were measured by dc polarization using a Hebb-Wagner's ion-blocking cell. The main charge carrier was electron for ceria-containi ng compositions (x greater than or equal to 0.1) in a whole range of measur ed oxygen partial pressure [log(p(O2)/Pa) = -6 to 3]. With increasing CeO2 concentration, the electronic conductivity drastically increased for x = 0- 0.5, slightly decreased for x = 0.5-1.0, and showed a maximum at x = 0.5. T he electronic conductivity is proportional to p(O2)(-1/4) at the higher oxy gen partial pressures and p(O2)(-1/m) (m > 4) at the lower oxygen partial p ressures. It is suggested that Ce4+ ions in ZrO2-CeO2-YO1.5 solid solutions with low CeO2 concentration were reduced more easily. The compositional de pendence of the electronic conductivity can be explained by the reduction o f Ce4+ to Ce3+ and the stabilization of Ce3+ ion in the [(ZrO2)(1-x)(CeO2)( x)](0.8)(YO1.5)(0.2) structure. (C) 2001 The Electrochemical Society.