Characterization of Nd1-xSrxMnO3±δ SOFC cathode materials

The crystal structure, thermal expansion behavior and electrical conductivity of Nd1-xSrxMnO3+/-delta (x = 0-0.5) perovskite oxides were investigated The chemical compatibility of the compositions with 40 and 50 mol% Sr with Gd2O3 doped CeO2 (CGO) electrolyte was also studied. An orthorhombic GdFeO3-type symmetry (space group Pbnm, z=4) was identified for all perovskite oxides, and the lattice parameters were determined. As the level of Sr doping increases, the pseudo-cubic lattice constant decreases, and the thermal expansion coefficient increases. The electrical conductivity can be described by the small polaron hopping conductivity model. The conductivity increases on increasing Sr doping, while the activation energy decreases. The compositions with 40 and 50 mol% Sr show very good thermal expansion and chemical compatibility with CGO electrolyte and can be considered as candidate intermediate temperature solid oxide fuel cell cathode materials. (C) 1999 Elsevier Science Limited All rights reserved.