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.
Highlights
Materials based on barium cerate are widely study as potential proton-conducting solid-state electrolytes
The effect of Ionics (2016) 22:1405–1414 microstructure on the grain boundary electrical properties seems to be a more complex issue. As it was reported for gadolinium and niobium-doped barium cerate, the specific grain boundary conductivity seems to be independent on the grain size [8, 9]
Samples of Y-doped barium cerate were synthesised by a solid-state reaction method
Summary
Materials based on barium cerate are widely study as potential proton-conducting solid-state electrolytes. Concerning the blocking effect of grain boundaries especially for barium zirconate and barium cerate materials, the increase of total conductivity can be observed for smallgrain size samples. The effect of microstructure on electrical properties of BaCeO3-based materials was not extensively studied. The effect of Ionics (2016) 22:1405–1414 microstructure on the grain boundary electrical properties seems to be a more complex issue. As it was reported for gadolinium and niobium-doped barium cerate, the specific grain boundary conductivity seems to be independent on the grain size [8, 9]. The activation energy of grain boundary conductivity shows significant changes with the microstructure [10]. For materials based on barium compounds sintered in the relatively high temperature, the change in the composition of grain boundaries caused by e.g. barium vaporisation or segregation of second phases on the grain boundaries can result in a decrease of grain boundary conductivity [5]
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