Preparation and ionic conduction of CaZr1−xScxO3−α ceramics

A series of CaZr1−xScxO3−α (x=0, 0.05, 0.10, 0.15) perovskite oxide ceramics were successfully fabricated at 1400 °C for 10 h and then further sintered at 1650 °C for 10 h via a solid-state reaction sintering process. Conductivities of the ceramics were measured under the atmosphere that contains 1% H2/Ar and 5.63 kPa H2O/Ar by the electrochemical impedance spectra technique. It was found that the conductivities of CaZr1−xScxO3−α (x=0, 0.05, 0.10, 0.15) ceramics increased with the increase of the measuring temperature, and the conductivity achieved its maximum value of 2.03×10−5–6.5×10−3 S cm−1 when the doping amount of Sc (x) was 0.10. Additionally, element doping can increase the conductivities and decrease the conductivity activation energies of CaZr1−xScxO3−α ceramics. The results of transport number measurement indicated that the CaZr0.9Sc0.1O3−α is almost a pure protonic conductor at 500–750 °C, while it is a mixed protonic-oxygen ionic-electronic conductor at 750–1300 °C.