Tetragonal tungsten bronze type phases (Sr1-xBax)0.6Ti0.2Nb0.8O3-δ:: Material characterisation and performance as SOFC anodes

The oxide material Sr0.2Ba0.4Ti0.2Nb0.8O3 was investigated for application as a potential anode material in solid oxide fuel cells (SOFCs). impedance spectroscopy in air and DC conductivity measurements under varying oxygen partial pressure revealed high electronic conductivity of 10 S cm(-1) [p(O-2)=10(-20) atm and 930 degreesC]. Additionally these anode materials were tested in SOFC single cells. AC-impedance measurements under operation showed a Warburg type behaviour, which indicated a diffusion limited process. This diffusion limitation is most likely due to either low oxide ion conduction of the anode or due to a reaction layer formed during sintering of the anode onto the electrolyte at the relatively high temperatures of above 1250 degreesC. Reactivity tests between YSZ electrolyte material and the Sr0.2Ba0.4Ti0.2Nb0.8O3 anode up to 1300 degreesC showed the formation of t-ZrO2. (C) 2000 Elsevier Science B.V. All rights reserved.