Effect of microstructure on chemical stability and electrical properties of BaCe0.9Y0.1O3 − δ

Abstract

Y-doped barium cerate BaCe0.9Y0.1O3 − δ was synthesised by a solid-state reaction method. Materials with different average grain sizes and grain boundary surface areas were obtained. The effect of microstructure on the chemical stability in the CO2 and H2O-containing atmosphere and electrical properties was analysed and discussed. To evaluate the chemical stability of BaCe0.9Y0.1O3 − δ, the exposure test was performed. Samples were exposed to the carbon dioxide and water vapour-rich atmosphere at 25 °C for 700 h. Thermogravimetry supplied by mass spectrometry was applied to analyse the samples before and after this comprehensive test. The mass loss for samples before and after the test and the amount of BaCO3 formed during the test were directly treated as the measure of chemical instability of BaCe0.9Y0.1O3 − δ in the atmosphere rich in carbon dioxide and water vapour. As it was observed, the BaCe0.9Y0.1O3 − δ chemical stability towards CO2 and H2O is not affected by the materials’ microstructure. Electrical properties of BaCe0.9Y0.1O3 − δ which differs with microstructure were determined using electrochemical impedance spectroscopy (EIS). It was found that the grain interior resistivity and activation energy of grain interior conductivity is microstructure independent. However, the effect on microstructure was seen on the EIS spectra in the range of grain boundary contribution. Therefore, the lowest activation energy and the highest conductivity were observed for a material with the lowest grain boundary surface area.