Electrical and microstructural characterisation 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 and (La0.8Sr0.2)(Mn1-xAlx)O-3 (x from 0 to 0.94) were evaluated as possible solid oxide fuel cell (SOFC) cathodes. Cell parameters of solid solutions were calculated. The electrical and microstructural characteristics and high temperature interactions with YSZ were studied. As compared with 'pure' perovskites, doping with strontium and aluminium decreases and increases their specific resistivity, respectively. The incorporation of alumina and strontium oxide substantially reduces the sinterability resulting in a rather porous, fine grained microstructure. The reaction rate between perovskite materials and YSZ at high temperatures is higher for lanthanum manganites than for lanthanum ferrites, and the partial exchange of cations on 'B' sites with aluminium decreases the reaction rate.