| Abstrakt: |
Cathode powders of Ba0.5Sr0.5(Co1−xMgx)0.2Fe0.8O3system (where x= 0, 0.2, 0.4, 0.6, 0.8, 1) were prepared by solid-state reaction route with an objective to reduce the coefficient of thermal expansion (CTE) by lowering Co concentration and by doping Mg for low-temperature solid oxide fuel cell (SOFC) applications. The relative density of the produced cathodes was measured, and from the values, the presence of porosity was observed. With the increased sintering temperature from 900 to 1175 °C, the density was significantly increased. X-ray diffraction analysis was carried out for all the samples, and formation of no new phases was observed. The average crystallite size was measured as ~ 18 nm with perovskite type structure. The lattice parameters were calculated, and the unit cell dimension (a) was measured as increased with the increased content of Mg. The temperature-dependent electric conductivity of the prepared samples was measured from room temperature to 800 °C. Highest conductivity was observed for the cathode with Co0.08and Mg0.12composition. The presence of Co showed profound effect on increasing the electric conductivity of the cathode material compared with Mg. However, coefficient of thermal expansion (CTE) was observed as lower (13.5 × 10–6/°C) for Mg-rich and Co-free cathode, which is favourable for SOFC applications. The results demonstrate the promising role of doping Mg ion in developing low-temperature SOFCs. |
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