Electrical conductivity of nanostructured acceptor-doped ceria fabricated by Spark Plasma Sintering (SPS)

High purity nanoscale powders (∼10-15 nm size) of two different compositions of ceria, doped with Gd3+ and Ca2+, have been consolidated by spark plasma sintering (SPS) at different temperatures. Fully-dense samples were observed only at a sintering temperature of 980 °C. The as-sintered samples showed rather fast grain growth with an average grain size below 300 nm. The electrical properties of the samples were evaluated by impedance spectroscopy over a wide range of temperatures (300-550 °C) in air. Electrical conductivity significantly enhanced with increasing sintering temperature. The compounds show an electrical blocking effect at the grain boundary, depending on the doping cations.