Electrical properties of Tb-doped barium cerate

摘要

The electrical conductivity of Ba_(0.8)Ce_(1-x)Tb_xO_(3-δ) (0 ≤ x≤0.15) has been studied in air and moist reducing atmosphere (5% H_2 in Ar) in the temperature range between 550 and 900℃. The powders of such materials are prepared by the combustion synthesis technique. The microstructure of the sintered specimens correlates well with its electrical properties. Electrical conduction mechanism of sintered specimens in various atmospheres is explained with respect to defect sites formed within the material. The generation of hydroxyl vacancy, proton and hole in moist reducing atmosphere increases the protonic conductivity significantly compared to hole/oxide ion conductivity in air atmosphere. Grain and grain boundary conductivity have been determined from the impedance measurements. The complex mechanism of electrical conduction of the sintered materials does not follow the linear behaviour in the Arrhenious plot. Maximum electrical conductivity obtained under moist reducing atmosphere is 0.049 S cm~(-1) for Ba_(0.8)Ce_(0.85)Tb_(0.15)O_(3-δ) at 900℃.