Document Type : Original Article
Author
Ambo University, College of Natural & Computational Sciences, Department of Physics
Abstract
The aim of this study is to investigate the structural, morphological, and electrical properties of ceria co-doped with samarium and lanthanum (LSDC) for application as an electrolyte in solid oxide fuel cells operating at lower temperatures. To assess the crystal structure, microstructure, and electrical characteristics, techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and impedance spectroscopy were employed. The findings from XRD indicated that all samples crystallized into a single-phase, cubic fluorite structure, with crystallite sizes ranging from 20 to 29 nm. Confirmation of grain formation, along with average grain sizes between 380 and 966 nm, as well as the presence of pores, is determined by the SEM micrograph. The conductivity values determined through impedance spectroscopy for the compositions Ce0.9Sm0.05La0.05O1.95, Ce0.85Sm0.05La0.1O1.925, Ce0.85Sm0.1La0.05O1.925, and Ce0.8Sm0.1La0.1O1.9 were 4.28x10-3 S/cm, 6.5x10-3 S/cm, 1.63x10-2 S/cm, and 1.13x10-2 S/cm, respectively, at a temperature of 500 0C in an air atmosphere. The activation energies calculated for the samples Ce0.9Sm0.05La0.05O1.95, Ce0.85Sm0.05La0.1O1.925, Ce0.85Sm0.1La0.05O1.925, and Ce0.8Sm0.1La0.1O1.9 are 0.83 eV, 0.76 eV, 0.64 eV, and 0.67 eV, respectively. Among the LSDC-series samples, the composition Ce0.85Sm0.1La0.05O1.925 exhibits the highest ionic conductivities and the lowest activation energies across all measured temperatures. Additionally, every LSDC sample demonstrated ionic conductivities greater than 10-3 S/cm, even at the reduce temperature of 400 °C. These results collectively validate that the co-doping of samarium and lanthanum in ceria enhances its structure, morphology, and ionic conductivity, making it a viable strong electrolyte for applications in low-temperature solid oxide fuel cells.
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