Study of microstructure and electrochemical properties of zirconium-doped barium cerium oxide

• Main Authors: Chia-Han Yang, 楊佳翰
• Other Authors: 曾重仁
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/qy2ae8

碩士 === 國立中央大學 === 能源工程研究所 === 107 === This study explores the relationship between the ratio of cerium and zirconium to study the relationship between the microstructure and electrical properties of barium cerium oxide with different zirconium doping ratios. In this study, BaCe0.8-xZrxY0.2O3-δ (BCZYx, x=0.1~0.5) electrolyte powder was successfully prepared by solid state reaction method. As the increase of Zr doping ratio, the XRD diffraction angle of the main peak of perovskite increased, indicating Zr successfully doped into the BaCeYO3. The SEM microstructure shows that as the Zr doping ratio increases, the grain size decreases, causing increase the grain boundary length of the barium cerium oxide, resulting in increase grain boundary impedance. The proton conductivity results show that as the Zr ratio increases, the highest proton conductivity is 0.010 S/cm at 700 °C when the Zr doping ratio is 0.3. But when the zirconium doping ratio increase to 0.4, the conductivity begins to decrease. The reason for this is because the carrier concentration and crystal structure vary with the Zr doping ratio. The conductivity results under humidified hydrogen show that the trend is consistent with that of non-humidification. BCZY0.3 also has the highest proton conductivity of 0.014 S/cm at 700 °C. This result also proves that the humidified atmosphere can enhance the proton conduction. In this study, Electron back scattered diffraction (EBSD) was also used to identify the crystal structure of different samples. The results of the mapping showed that all samples had the highest proportion of orthorhombic crystals. In addition, in this study, BCZY0.3 electrolyte was prepared by using different particle size powders. The performance results show that as the size of the zirconium beads used is reduced, it contributes to the improvement of electrolyte density, and the use of 1 mm zirconium beads of the electrolyte has a maximum power density of 84 mW/cm2 at 700 oC.