Sintering and conductivity of BaCe0.9Y0.1O2.95 synthesized by the sol–gel method

Ceramic powders of BaCe0.9Y0.1O2.95 (BCY10) have been prepared by the sol–gel method. Barium and yttrium acetate and cerium nitrate were used as ceramic precursors in a water solution. The reaction process studied by DTA–TG and XRD showed that calcination of the precursor powder at T ≥ 1000 °C produces a single perovskite phase. The densification behaviour of green compacts studied by constant heating rate dilatometry revealed that the shrinkage rate was maximal at 1430 °C. Sintered densities higher than 95% of the theoretical one were thus obtained below 1500 °C. The bulk and additional blocking effects were characterized by impedance spectroscopy in wet atmosphere between 150 and 600 °C. A proton conduction behaviour was clearly identified. The blocking effect can be related to a space-charge depletion layer of protons in the vicinity of grain boundaries.

► Very fine yttrium-doped barium cerate powders were synthesized. ► Relative densities as high as 95% of the theoretical one were achieved. ► Bulk and blocking contributions were clearly separated by impedance spectroscopy. ► The blocking effect originates from space charge layers.