| Synthesis and Characterization of Co-Doped Ceria Ceramics by Sol-Gel Method |
| S. Ramesh*, K. C. James Raju and C. Vishnuvardhan Reddy** |
| Abstract |
| Doped and co-doped ceria electrolyte materials are very useful in solid oxide fuel cells. The Ce0.9Sm1–xSrxO2 (x = 0-0.09) compositions were synthesized through the sol-gel method. Dense Ce0.9Sm1–xSrxO2 ceramics were obtained through sintering the pellets at 1300oC for 8 h. XRD measurements indicate that all synthesized materials crystallized in cubic fluorite-type structure. Average crystallite size of the samples was in the range 21-27 nm. The relative density of Ce0.9Sm1–xSrxO2 samples was over 94% of the theoretical density. The lattice parameter increased linearly with increasing Sr concentration in Ce0.9Sm1–xSrxO2 following Vegard’s rule. Surface morphology was analyzed using SEM. It was observed that the thermal expansion increased linearly with increasing temperature. The two-probe a.c. impedance spectroscopy was used to study the grain, grain boundary and total ionic conductivity of doped and co-doped ceria in the temperature range 250o-500oC. The Ce0.9Sm0.07Sr0.03O2 composition showed higher grain ionic conductivity and minimum activation energy at 500oC. |
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