Structural and electrical characterisation of silica-containing yttria-stabilised zirconia

Zirconia stabilised by yttria has a high oxide ion conductivity at high temperature and therefore, is currently used as electrolyte in Solid Oxide Fuel Cells. Silica is normally avoided in this material because formation of amorphous silica phases along the grain boundaries causes an increased grain boundary impedance. The present study examines the effect of SiO2 and SiO2 with Mn-oxide on the structure and resistivity of yttria stabilised zirconia electrolyte materials. During fabrication of Solid Oxide Fuel Cells, Mn readily diffuses from the manganite-based cathode into the electrolyte. It is shown that a grain boundary phase which causes an insulating layer in the grain boundaries is formed when both SiO2 and Mn-oxide coexist in the samples, whereas such effects are much less pronounced when only SiO2 is present. (C) 1999 Elsevier Science Limited. All rights reserved.