Synthesis and Electrical Characterisation of the Doped Perovskite Titanates as Potential Anode Materials for Solid Oxide Fuel Cells

This work reports the synthesis and electrical characterisation over a range of oxygen partial pressures (10(-20)-1 atm) of the A-site deficient perovskites Sr1-3x/2LaxTiO3-delta , with a view to establishing their potential as anode materials for solid oxide fuel cells. Single phase samples were observed for synthesis in air for 0 less than or equal to x less than or equal to 0.6, and the materials remained phase pure for both high and low oxygen partial pressures at the measurement temperature of 930 degrees C. Good electrical conductivity, which increased with increasing La content, was observed on reduction in low oxygen partial pressures, with values as high as 7 S cm(-1) [P(O-2)=10(-20) atm], similar to values observed for the related system, Sr1-x/2Ti1-xNbxO3-delta, examined previously. The conductivity of the fully reduced samples showed metallic character from 100 to 930 degrees C. As the oxygen partial pressure was raised, the conductivity dropped, showing an approximate CP(O,)I-lis dependence for porous samples. New samples, Sr1-y/2-3x/2LaxTi1-yNbyO3-delta, With both La and Nb substitutions, were also studied, and these phases showed similar electrical behaviour. Further results for the Sr1-x/2Ti1-xNbxO3-delta system are presented and compared with the La doped systems.