Long-term degradation of Ta2O5-doped Bi2O3 systems |
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Authors: | SE LinWCJ Wei |
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Affiliation: | Dept. Mat. Sci. Eng., National Taiwan University, 1 Roosevelt Rd., Sect. 4, Taipei 106, Taiwan, ROC |
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Abstract: | Bismuth oxide in δ-phase is a well-known high oxygen ion conductor and can be used as an electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). 5-10 mol% Ta2O5 are doped into Bi2O3 to stabilize δ-phase by solid state reaction process. One Bi2O3 sample (7.5TSB) was stabilized by 7.5 mol% Ta2O5 and exhibited single phase δ-Bi2O3-like (type I) phase. Thermo-mechanical analyzer (TMA), X-ray diffractometry (XRD), AC impedance and high-resolution transmission electron microscopy (HRTEM) were used to characterize the properties. The results showed that holding at 800-850 °C for 1 h was the appropriate sintering conditions to get dense samples. Obvious conductivity degradation phenomenon was obtained by 1000 h long-term treatment at 650 °C due to the formation of α-Bi2O3 phase and Bi3TaO7, and 〈1 1 1〉 vacancy ordering in Bi3TaO7 structure. |
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Keywords: | Ta2O5 Bi2O3 Fuel cell Annealing Conductivity |
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