ELECTRICAL AND MICROSTRUCTURAL CHARACTERIZATION OF (LA0.8SR0.2)(FE1-XALX)O-3 AND (LA0.8SR0.2)(MN1-XALX)O-3 AS POSSIBLE SOFC CATHODE MATERIALS

The perovskites with nominal compositions (La0.8Sr0.2)(Fe1-xAlx)O-3 an d (La0.8Sr0.2)(Mn1-xAlx)O-3 (x from 0 to 0.94) were evaluated as possi ble solid oxide fuel cell (SOFC) cathodes. Cell parameters of solid so lutions were calculated. The electrical and microstructural characteri stics and high temperature interactions with YSZ were studied. As comp ared with 'pure' perovskites, doping with strontium and aluminium decr eases and increases their specific resistivity, respectively. The inco rporation of alumina and strontium oxide substantially reduces the sin terability resulting in a rather porous, fine grained microstructure. The reaction rate between perovskite materials and YSZ at high tempera tures is higher for lanthanum manganites than for lanthanum ferrites, and the partial exchange of cations on 'B' sites with aluminium decrea ses the reaction rate.