SYNTHESIS AND ELECTRICAL CHARACTERIZATION OF 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 defic ient perovskites Sr1-3x/2LaxTiO3-delta , with a view to establishing t heir potential as anode materials for solid oxide fuel cells. Single p hase samples were observed for synthesis in air for 0 less than or equ al to x less than or equal to 0.6, and the materials remained phase pu re for both high and low oxygen partial pressures at the measurement t emperature of 930 degrees C. Good electrical conductivity, which incre ased with increasing La content, was observed on reduction in low oxyg en 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 reduc ed 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 behaviou r. Further results for the Sr1-x/2Ti1-xNbxO3-delta system are presente d and compared with the La doped systems.