Microstructural and Electrical Conductivity Relationships in Alumina- Containing Yttria Stabilized Cubic Zirconia Used as a Solid Electrolyte in Solid Oxide Fuel Cells

Abstract

Cubic zirconia is a well known material that has good oxygen ionic conductivity and chemical stability over wide ranges of temperature and oxygen partial pressure and thus it has been developed for use in a variety of electrical applications such as oxygen sensors, oxygen pumps, thermal barriers and solid oxide fuel cell electrolytes. In the present study, the effect of Al2O3 addition on the microstructure and electrical conductivity of 8 mol% yttria stabilized cubic zirconia doped with up to 10 wt% Al2O3 was investigated. The electrical conductivity of the specimens was measured using a frequency response analyzer in the frequency range of 5-13 MHz and in the temperature range of 300-800 oC. The experimental results showed that the addition of Al2O3 led to decreased grain size due to grain boundary pinning and increased grain boundary volume. It was also seen that grain conductivity slightly increased with increasing Al2O3 content up to 1 wt% and further increase in Al2O3 led to a decreased in the conductivity.