Investigation on Sintering and Electrical Conductivity of Ceria-based Materials by Addition of Multiple Metal Oxides

• Main Authors: Ting-Yi Yang, 楊庭懿
• Other Authors: Wen-Cheng J. Wei
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/pn46b6

碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 107 === Ceria-based electrolyte materials are synthesized by an EDTA-citric acid method. Two samples, Ce0.9Sm0.1O2 (ST00) and Ce0.9Sm0.09Fe0.005Mn0.005O2 (S9HH) are prepared and sintered to single cubic fluorite structure and still kept within solution limit. The microstructure and electrical properties are analyzed, showing S9HH having >99% theoretical density (T.D.) observed by SEM after sintered at 1250 ℃ for 5 hr, and suitable for an electrolyte of solid oxide fuel cell. Bulk electrical conductivity of S9HH and ST00 is a liner relationship to the reverse of the temperature (1/T). The bulk electrical conductivity of S9HH samples is 7.15*10-2 S•cm-1 higher than that of ST00 samples 2.60*10-2 S•cm-1 at 800 ℃. Both of the activation energy of ceria-based materials are around 1.10-1.20 eV, indicating the same conductivity mechanism by oxygen vacancy/ion exchange and diffusion. After an aging treatment at 650 ℃ for a holding time of 500 h, the electrical conductivity of S9HH reduces to 3.11*10-2 S•cm-1, but still higher than that of ST00 1.60*10-2 S•cm-1 at 800 ℃. The electrical conductivity degradation in long-term aging is because of the formation of continues Sm-rich fluorite sub-micro grains.