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Abstract: The aim of present investigation is to study the effect of co-doping of lanthanum and magnesium on the ionic conductivity of CeO2 for its use as a solid electrolyte in the intermediate temperature solid oxide fuel cells (IT SOFC). Attempts have been made to synthesize compositions with x =0.075, 0.07, 0.06, 0.05 and 0.00 and y =0.00, 0.01, 0.03, 0.05 and 0.15 in the system Ce1−x−y Mg x La y O2−x−y/2 (CML) by auto-combustion method. X-ray diffraction patterns show that all the samples have fluorite structure similar to undoped ceria. Microstructures of thermally etched samples have been studied by scanning electron microscopy (SEM). In order to evaluate the contributions of grains σ g, grainboundaries σ gb and electrode–specimen interface to the total conductivity σ t, use is made of AC impedance analysis. Impedance measurements are made in the frequency range 1Hz to 1MHz and temperature range 250–500°C. The results show that the conductivity of the system increases with increasing lanthanum content. There is no enhancement in conductivity due to co-doping with La and Mg. [Copyright &y& Elsevier]

Abstract: The aim of the present investigation was to study the effect of doping of magnesium and calcium on the ionic conductivity of CeO2 in the system Ce1−xCax−yMgyO2−x (x=0.150) for its use as a solid electrolyte in the intermediate temperature solid oxide fuel cells (IT SOFC).Attempts have been made to synthesize a few compositions in this system with x=0.150 and y=0.000, 0.050, 0.060, 0.065 and 0.070. The precursor materials have been synthesized by auto-combustion method. Solid solution forms in compositions with y≤0.060. Microstructures of thermally etched samples have been studied by scanning electron microscopy (SEM). In order to evaluate the total electrical conductivity, σt, use is made of complex plane impedance analysis. Impedance measurements were made in the frequency range 1Hz–1MHz and temperature range 250–500°C. It is found that co-doped samples show higher conductivity than undoped and singly doped samples. [Copyright &y& Elsevier]