Correlation between microstructure and ionic conductivity in cubic zirconia polycrystals

Abstract

Material based on stabilized zirconia is widely applied in electrochemical devices. Therefore its microstructure should be optimized with respect to its electrical properties. The ionic conductivity of zirconia is mainly determined by the crystallographic form of the zirconia solid solution – the cubic phase is a better medium for the transport of oxygen vacancies than the tetragonal phase. However, the final microstructure after sintering is also very important for the global conductivity of zirconia, even if it exists as a cubic phase. The correlation between the three-dimensional grain size distribution and ionic conductivity in cubic zirconia sintered with different mean grain size was investigated using three-dimensional electron backscatter diffraction (3D-EBSD) technique and impedance spectroscopy. The grain size distribution of sintered materials determines the grain boun\\dary density and strongly influences the ratio of grain boundary conductivity to bulk conductivity. Complex impedance spectroscopy analysis allowed a description of electrical properties and 3D-EBSD gave an insight to its internal microstructure.