Azad, Abul K. and Savaniu, Cristian and Tao, Shanwen and Duval, Sophie and Holtappels, Peter and Ibberson, Richard M. and Irvine, John T. S. (2008) Structural origins of the differing grain conductivity values in BaZr0.9Y0.1O2.95 and indication of novel approach to counter defect association. Journal of Materials Chemistry, 18 (29). pp. 3414-3418. ISSN 0959-9428Full text not available in this repository. (Request a copy from the Strathclyde author)
Proton conducting oxides such as BaCe0.9Y0.1O3-delta have considerable promise for intermediate temperature fuel cells. Unfortunately these tend to be unstable, e. g. to attack by carbonation. Previous work has highlighted the possibility of utilising barium zirconate to provide a chemically stable electrolyte; however such materials are difficult to sinter yielding very high overall resistances. Whilst this sintering problem is soluble, there are still very significant questions about the intrinsic grain conductivity, which varies by orders of magnitude for different reports. Here we demonstrate that there are two variants of BaZr0.9Y0.1O2.95, both with the cubic perovskite structure. The a-form exhibits a slightly smaller unit cell and much lower protonic conductivity than the beta-form. The alpha-form is observed in better equilibrated samples and neutron diffraction demonstrates that this difference originates in a small degree of cross substitution of the Y atom onto the A-sites for the beta-form, suggesting a novel approach to enhance ionic conductivity by reducing defect association through A-site substitution.
|Keywords:||CATION NONSTOICHIOMETRY, TRANSPORT-PROPERTIES, PROTON CONDUCTIVITY, CHEMICAL-STABILITY, OXIDES, SITE, DIFFRACTION, NEUTRON, BACEO3, Materials Chemistry, Chemistry(all)|
|Department:||Faculty of Engineering > Chemical and Process Engineering|
|Depositing user:||Pure Administrator|
|Date Deposited:||31 Oct 2011 12:51|
|Last modified:||15 Jul 2016 03:30|