Abstract
The influence of copper addition (0.5–2 mol%) on the crystal structure, densification microstructure, and electrochemical properties of Ce0.8Gd0.2O1.9 synthesized in a one-step sol–gel combustion synthesis route has been studied. It has been found that Cu is very active as sintering aids, with a significative reduction of GDC firing temperature. A reduction of 500 °C with a small amount of copper (0.5 mol%) was observed achieving dense bodies with considerable ionic conductivities. Rietveld refined was used to investigate the crystal structure while relative density and microstructural examination were performed in the sintering temperature range of 1000–1200 °C after dilatometer analysis. High dense bodies were fabricated at the lowest sintering temperature, which promotes the formation of Ce0.8(1−x)Gd0.2(1−x)CuxO[1.9(1−x)+x] solid solution and the absence of secondary phase Cu-rich or the segregation or copper at the grain boundary. As compared to the pure GDC an improvement of total conductivity was achieved with a maximum for the highest copper content of 2.23·10−3–9.19·10−2 S cm−1 in the temperature range of 200–800 °C.
Highlights
The development of ceramic ceria-based powders doped with rare earth elements is extensively regarded as favorable electrolytes type-component for intermediate and low-temperature solid oxide fuel cells (SOFCs)
This work purposes to evaluate the effect of copper precursor on the microstructure, densification, and ionic conductivity of Ce0.8 Gd0.2 O1.9 by mean a very simple and fast reproducible synthesis procedure as sol–gel combustion synthesis
Copper doped samples instead have a similar behavior above 450 ◦ C indicating that electrochemical properties are comparable while at temperatures lower than 450 ◦ C the differences are ascribed to the grain boundary conductivities
Summary
The development of ceramic ceria-based powders doped with rare earth elements is extensively regarded as favorable electrolytes type-component for intermediate and low-temperature solid oxide fuel cells (SOFCs). Additional polishing steps to remove the contaminants added during milling are often required before calcination and the inclusion of dispersants during compaction of the pellets can be a supplementary stage in the electrolyte preparation In this scenario, this work purposes to evaluate the effect of copper precursor on the microstructure, densification, and ionic conductivity of Ce0.8 Gd0.2 O1.9 by mean a very simple and fast reproducible synthesis procedure as sol–gel combustion synthesis. This study is the starting point to the optimization of the fabrication process of the anode-supported cells where the electrolyte should be densified even if the firing temperature is less than 1500 ◦ C to prevent the additional and unwanted densification of the supporting anode substrate For these reasons, the electrochemical properties were evaluated in the range of 200–800 ◦ C by impedance spectroscopy after the identification of the best sintering temperature
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