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

Zirconia stabilised by yttria has a high oxide ion conductivity at high tem perature and therefore, is currently used as electrolyte in Solid Oxide Fue l Cells. Silica is normally avoided in this material because formation of a morphous 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 zircon ia 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 th e grain boundaries is formed when both SiO2 and Mn-oxide coexist in the sam ples, whereas such effects are much less pronounced when only SiO2 is prese nt. (C) 1999 Elsevier Science Limited. All rights reserved.