Y2Zr2O7 (YZ)-pyrochlore based oxide as an electrolyte material for intermediate temperature solid oxide fuel cells (ITSOFCs) - Influence of Mn addition on YZ

Abstract

Compositions in the pyrochlore system Y2Zr2O7 (YZ) and Y2Zn2-xMnxO7-delta (YZM) (where x=0.025, 0.05, 0.075 and 0.10) were examined as possible alternatives to stabilised zirconia solid oxide electrolyte in intermediate temperature solid oxide fuel cells (ITSOFC). Such materials were prepared by glycine-nitrate combustion process. The prepared compounds were characterised by X-Ray Diffraction and Thermal analysis. Circular pellets were fabricated and annealed at different temperatures ranging from 1000 to 1400 degrees C. The sintering behaviour of YZ and YZM were investigated to obtain information on the densification factor, relative percentage shrinkage/expansion in volume after heat treatment and apparent porosity value. The small doping level of Mn (<= 10.0 wt%) resulted in increased conductivity values. The component diffusion coefficients and mobility of ions are calculated from its conductivity value. D-comp and mu(i) are found in the range of 10(-8) cm(2) s(-1) and 10(-7) cm(2) V-1 s(-1), respectively. The key features, which make the YZ and YZM systems attractive as a fuel cell electrolyte, are discussed. (C) 2007 Elsevier B.V. All rights reserved.