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Characterization of Co-doped LSGM electrolyte prepared by GNP for IT-SOFC Dokyol Lee, Ju-Hyeong Han* Korea University Department of Materials Science and Engineering, Korea University, 5-1 Anam-dong, Seongbuk-gu, Seoul 136713, Republic of Korea Introduction CeO2 and Bi2O3-based solid oxides are well-known electrolyte materials which show much higher electrical conductivity than yttria stabilizedzirconia(YSZ). But these materials become mixed ionic/electronic conductors in reducing atmospheres. On the contrary, strontium- and magnesium-doped lanthanum gallate has a wide range of electrolytedomain and high electrical conductivity. In our previous studies, La0.8Sr0.2Ga0.8Mg0.2O2.8(LSGM) showed the highest electrical conductivity among La1-xSrxGa1of various compositions[1, 2]. In thisstudy, Co-doped LSGM powders were prepared by glycine nitrate process(GNP) for the IT-SOFC electrolyte material with electrical conductivity even higher than LSGM and examined whether it would meet therequirements for the electrolyte (electrical conductivity, mechanical and chemical stability, sinterability). Experimental LSGM and La0.8Sr0.2Ga0.8Mg0.2-xCoxO2.8(LSGMC5 and LSGMC10 respectively forx=0.05 and 0.1) powders were prepared using GNP. After calcined at 1000°C for 2 hours, the powders were wet-milled for 24 hours using zirconia balls and ethanol. The slurry was dried in an oven andcrushed in a mano mortar. The powders were then passed through a #120 sieve(12 ㎛ size) and compacted into cylindrical pellets(12mm in diameter) under a pressure of 1ton/cm2. The pellets were sintered at1400°C for 4 hours in air and their ionic conductivities, thermal expansion coefficients and relative densities were measured for characterization. Results and discussion The Arrhenius plots for theelectrical conductivity of LSGM, LSGMC5 and LSGMC10 are shown in Fig. 1. Here you can see that the electrical conductivity increases with increasing Co content and the value is 0.145S/㎝ at 800℃ for...
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