High density and low temperature sintered proton conductor BaCe_0.5Zr_0.35Sc_0.1Zn_0.05O_3–δ

Rare-earth-doped BaCeO3 and BaZrO3 electrolytes with perovskite structure have been studied extensively in developing proton conducting intermediate temperature SOFC. Traditional solid state sintering has been used to prepare the perovskite type proton conductor BaCe0.5Zr0.35Sc0.1Zn0.05O3-delta. The density of the sample obtained about 96% of the theoretical density after sintering at 1350 degrees C and X-ray diffraction study confirms the pure phase. Rielveld refinement of the neutron and X-ray powder diffraction data shows that this material crystallizes in the orthorhombic symmetry in the space group Pbnm. Thermogravimetric analysis (TGA) traces obtained for the sample on heating in a 3%H2O/5%H-2/Ar atmosphere shows that the maximum water uptake occurs around 380 degrees C. AC impedance measurement under wet 5% H-2/Ar and dry 5% H-2/Ar shows that the material is a good conductor and the conductivity increases under wet atmosphere. The total conductivity in wet 5%H,/Ar at 600 degrees C and 900 degrees C is 1.12 x 10(-3) S cm(-1) and 3.46 x 10(-3) S cm(-1), respectively. (C) 2008 Elsevier B.V. All rights reserved.