Oxygen ion conductivity in ceria-based electrolytes co-doped with samarium and gadolinium
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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, Ce0.825SmxGd0.175-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 °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 °C and above. This compares favourably with previously-reported values and has promising implications for the development of IT-SOFCs.
Coles-Aldridge , A V & Baker , R T 2020 , ' Oxygen ion conductivity in ceria-based electrolytes co-doped with samarium and gadolinium ' , Solid State Ionics , vol. 347 , 115255 . https://doi.org/10.1016/j.ssi.2020.115255
Solid State Ionics
Copyright © 2020 Elsevier B.V. All rights reserved. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1016/j.ssi.2020.115255
DescriptionThe authors thank the University of St Andrews and the UK Engineering and Physical Sciences Research Council for the PhD studentship for AVC-A (grant code: EP/M506631/1). Electron microscopy was performed at the Electron Microscope Facility, University of St Andrews.
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