Synthesis and characterization of (Pr_0.75Sr_0.25)_1-xCr_0.5Mn_0.5O_3-δ as anode for SOFCs

The complex perovskite (Pr0.75Sr0.25)(1-x)Cr0.5Mn0.5O3-delta (PSCM) has been prepared and studied as possible anode material for high-temperature solid oxide fuel cells (SOFCs). PSCM exhibits GdFeO3-type structure and is both physically and chemically compatible with the conventional YSZ electrolyte. The reduction Of PSCM resulted in structural change from orthorhombic Pbnm to Cubic Pm-3m. Selected area electron diffraction (SAED) analysis on the reduced phases indicated the presence of a root 2 x root 2 x 2 superlattice. The total conductivity values of similar to 75% dense Pr0.75Sr0.25Cr0.5Mn0.5O3-delta at 900 degrees C in air and 5% H-2/Ar are 9.6 and 0.14 Scm(-1) respectively. The conductivity of PSCM drops with decreasing Po-2 and is a p-type conductor at all studied Po-2. The average TEC of Pr0.75Sr0.25Cr0.5Mn0.5O3-delta in the temperature range of 100-900 degrees C and is close to that of YSZ electrolyte. The anode polarization resistance of PSCM ill wet 5%H-2 is 1.31 Omega cm(2) at 910 degrees C and in wet CH4 at 930 degrees C: the polarization resistance is 1.29 Omega cm(2). PSCM was unstable at 900 degrees C in unhumidified hydrogen. Cell performance measurements carried Out Using graded PSCM and La0.8Sr0.2MnO3 as anode and cathode respectively yielded a maximum power density of 0.18 W cm(-2) in Wet 5%H-2/Ar at 910 degrees C and the corresponding current density was 0.44 A cm(-2) at 0.4 V. The activation energy for the electrochemical cell operating in wet (3% H2O) 5%H-2/Ar fuel is 85 kJ mol(-1). (C) 2009 Elsevier B.V. All rights reserved.