Synthesis and characterization of GdCoO3 as a potential SOFC cathode material

Gadolinium cobaltite (GdCoO3) powder has been synthesized by solution polymerization method and characterized for its application as cathode material in gadolinia doped ceria (GDC) electrolyte based intermediate temperature SOFC (IT-SOFC). Perovskite structured phase pure and nanocrystalline GdCoO3 powder was obtained after calcining the precursor at 800 degrees C. The powder was found to start sintering at about 850 degrees C on heating and could be sintered to near theoretical density at 1200 degrees C. The electrical conductivity of the sintered material was measured to be 580 S cm(-1) at 800 degrees C and its coefficient of thermal expansion varied from 16 x 10(-6) to 25 x 10(-6) K-1 in the temperature range from 200 to 1000 degrees C. GdCoO3-GDC (1:1 wt.%) composite cathode was found to have coefficient of thermal expansion that match closely with GDC electrolyte. Symmetric cells were prepared using GDC electrolyte and GdCoO3-GDC composite as the electrode and the area specific resistance (ASR) for interfacial polarization was evaluated by AC impedance spectroscopic technique. ASR values of 1.1, 0.55 and 0.2 Omega cm(2) have been obtained at 800, 850 and 900 degrees C, respectively.(C) 2012 Elsevier B.V. All rights reserved.