The influence of anionic heterovalent doping on transport properties and chemical stability of F-, Cl-doped brownmillerite Ba2In2O5

The novel Cl-doped compound based on brownmillerite Ba2In2O5 was synthesized by the solid state method and its structure, thermal properties, hydration behavior and electrical properties have been investigated. The thermogravimetry, mass spectrometry and impedance spectroscopy methods were used for the characterization of the materials. The conductivity was measured at T, pO(2) and pH(2)O variation. The sample Ba1.95In2O4.9Cl0.1 was capable to water uptake, however in comparison with Ba2In2O5 and F-doped composition, the protonic conductivity was lower owing to the lower proton mobility. The changes in the chemical O-H bonding due to introduction of halogen in oxygen sublattice play an important role in the hydrogen-migration process. It was found that anionic heterovalent doping (F, Cl) of brownmillerite Ba2In2O5 leads to an increase in oxygen-ion conductivity and chemical stability against carbon dioxide. (c) 2017 Elsevier B.V. All rights reserved.