Grain boundary segregation and its influences on ionic conduction properties of scandia doped zirconia electrolytes |
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Authors: | Qiannan Xue Xiaowei Huang Jianxing Zhang He Zhang Zongyu Feng |
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Affiliation: | 1. National Engineering Research Center for Rare Earth Materials, General Research Institute for Nonferrous Metals, Beijing 100088, China;2. Grirem Advanced Materials Co., Ltd., Beijing 100088, China |
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Abstract: | Solid oxide fuel cell is a promising energy conversion system which converts chemical energy into electrical energy directly. Electrolyte is the key component and determines the working temperature. In this paper, ceria and scandia co-doped zirconia electrolytes sintered from 1300 to 1550 °C were chosen as research objects. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy were performed to characterize the ceramic samples. The effects of grain size and grain boundary element segregation on the electrical conductivity were focused. Electrochemical impedance spectroscopy was used to calculate the bulk, grain boundary and specific grain boundary conductivity. Results show that the bulk and grain boundary ionic conductivity increases with the increasing grain size. However, the specific grain boundary conductivity decreases with the increasing grain size. This is explained by the fact that Sc3+ is segregated at the grain boundary, which leads to higher oxygen vacancy concentration when sintered at lower temperature. |
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Keywords: | Corresponding author. National Engineering Research Center for Rare Earth Materials, General Research Institute for Nonferrous Metals, Beijing 100088, China. Electrolytes Co-doped zirconia Grain size Dopant segregation Ionic conductivity Rare earths |
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