Effect of Niobium Doping on the Properties of Yttria-Stabilised Zirconia for Solid Electrolyte in Solid Oxide Fuel Cell

Abstract

8 mol % Yttria Stabillize Zirconia (8YSZ) generally used as solid electrolyte in solid oxide fuel cell (SOFC). In this study, niobium (0, 1, 2, 3 mol%) doped 8YSZ ceramics were prepared by the conventional solid state process. The mixtures of powders were calcined, compacted into cylinderical pellets, and sintered at 1500°C for 2 hours in air atmosphere. All samples were evaluated for phase stability, microstructure and electrical conductivity. Tetragonal phase was detected as the major phase for all studied samples. With increasing in Nb addition, tetragonal and cubic phase started to transform to monoclinic phase. The introduction of Nb2O5 (more than 0.5 mol %) was not only useful to enhance the densification, but also helpful to enhanced the ionic conductivity of 8YSZ samples. SEM micrographs of niobium-doped zirconia powders indicated the coalesce of fine particles with sizes varying from 10 μm to 1 μm, in response to increasing in Nb content.