Chemical Stability and Electrical Conductivity of Ba0.8Ce0.85-xZrxTb0.15O3-δ Proton Conductors with ZnO as Sintering Aid

The chemical stability of Ba0.8Ce0.85-xZrxTb0.15O3-delta (0.1 <= x <= 0.5) has been studied in dry 5% H-2/Ar, wet 5% H-2/Ar and dry CO2 atmosphere at higher temperature. These materials are promising candidates for mixed ionic electronic conductor based H-2 separation membr ane. The materials are prepared by combustion synthesis technique successively followed by calcination at 1100 degrees C and sintering at 1550 degrees C in air. The stabilization mechanism of sintered specimens in various atmospheres is explained with respect to the combined effect of zirconium oxide and zinc oxide as stabilizing agent and sintering aid respectively. Zr4+ introduction into Ce4+ site of doped bar ium cerate perovskite enhances the chemical stability of these materials, particularly for the composition with x>0.3. The stable sintered material is obtained with total electrical conductivity of 0.0189 S.cm(-1) for the composition Ba0.8Ce0.35Zr0.5Tb0.15O3-delta in moist reducing atmosphere at 900 degrees C. So, in the present work, we report a composition which shows excellent stability in pure CO2 atmosphere at high temperature without much compromising its ionic conductivity.