Journal
SOLID STATE IONICS
Volume 347, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.ssi.2020.115255
Keywords
Solid oxide fuel cell; Electrolyte; Ceria; Doping; Ionic conductivity; Activation energy
Categories
Funding
- University of St Andrews
- UK Engineering and Physical Sciences Research Council [EP/M506631/1]
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In a systematic study, two compositional series of ceria-based oxides, both co-doped with Sm and Gd, were synthesised using a low temperature method and evaluated as oxygen ion-conducting electrolytes for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs). Series one, Ce1-2xSmxGdxO2-x had equal concentrations of Sm and Gd but varying total dopant concentration. Series two, Ce-0.825,SmxGd0.175-xO1.9125, had a fixed total dopant concentration but the Sm:Gd concentration ratio was varied. The materials were characterised using scanning and transmission electron microscopy, inductively coupled plasma mass spectrometry and X-ray diffraction. Impedance spectra were recorded on dense pellets of these materials. From these, total, bulk and grain boundary conductivities and capacitances along with activation energies, pre-exponential constants and enthalpies of ion migration and defect association were obtained. These gave a detailed insight into the fundamental conduction processes in the materials. Ce0.825Sm0.0875Gd0.0875O1.9125 had the highest total ionic conductivity at temperatures of 550 degrees C and above and also demonstrated an enhanced conductivity with respect to its singly-doped parent compounds, Ce0.825Sm0.175O1.9125 and Ce0.825Gd0.175O1.9125, at 400 degrees C and above. This compares favourably with previously-reported values and has promising implications for the development of IT-SOFCs.
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