Effect of CuO on microstructure and conductivity of Y-doped BaCeO3

Effect of CuO additions on sinterability and conductivity of BaCe0·85Y0.15O2.925 was studied. Two different amounts, 0.75 and 1.5 wt% with respect to the pure powder, were considered. Microstructural characterization showed that for smaller additions Cu was completely incorporated on B-site of the perovskite, while formation of the secondary phase Y2BaCuO5 was detected when higher amount of CuO was added. Enhanced cations diffusivity at grain boundary is responsible for a pronounced reduction of sintering temperature and grain growth. Density as high as 96-97% of theoretical value was obtained when sintering at 1000 °C for 2 h. As long as Cu is incorporated in the perovskite, higher conductivity and lower activation energy of grain core were found. In addition, total conductivity of 0.75 wt% doped material was limited by fine grain size that resulted in apparent poor conductivity of the grain boundary. On the contrary when Cu segregates in the Y2BaCuO5 phase, overall conductivity increased mostly because of the contribution from the electronic conductivity of that phase.