Characterization of the La1-xBaxCoO3-d; (0< x< 1) system as cathode material for IT-SOFC

C.SETEVICH; L. MOGNI; A. CANEIRO; F. PRADO

JOURNAL OF THE ELECTROCHEMICAL SOCIETY

ELECTROCHEMICAL SOC INC

Año: 2012 vol. 159 p. 73 - 80

0013-4651

The influence of temperature and procedure on the phase relationships of LaxBa1-xCoO3-d with 0 < x < 1.0, the contribution of the thermal and chemical expansion, in air, and the electrochemical response of electrodes formed by three porous layers of LaxBa1-xCoO3-d /(50:50wt%)LaxBa1-xCoO3-d+Ce0.9Gd0.1O1.95/Ce0.9Gd0.1O1.95 have been investigated. Samples were found to be single phase for 0 < x < 0.5 and x = 1.0. The cubic perovskite phase could be obtained for the x = 0.5-0.7 furnace-cooled samples (~ 5 °C/min). This phase was found unstable for x = 0.6 and 0.7, in air, at T <1000 °C. For the x = 0.8 and 0.9 samples a mixture of phases has been obtained. The expansion coefficient reaches a maximum of 26  10-6 K-1 for x = 0.6 and a minimum of 16  10-6 K-1 for the x = 0.8 and 0.9 samples for T = 20-900 C. AC impedance spectroscopy measurements were carried out in the intermediate temperature range of 400 < T < 700 °C. A minimum polarization resistance value of Rp ~ 0.065 - 0.075 Ohm cm2 was obtained for 0.4 < x < 0.7 at T = 600 °C, which compares very well with the Rp value reported for composites prepared with cobaltites.