Preparation and electrical conductivity of core-shell structured Ce0.8Sm0.2O1.90-δ@xBaCe0.8Sm0.2O2.95-δ (x = 0, 0.5, 1, 1.5) ceramics

Abstract

Core-shell structured powders of Ce_0.8Sm_0.2O_1.90-δ(SDC)@xBaCe_0.8Sm_0.2O_2.95-δ(BCS) (x = 0, 0.5, 1, 1.5) were synthesized by a two-step co-precipitation method and then sintered to prepare the corresponding SDC@xBCS (x = 0, 0.5, 1, 1.5) ceramics. The XRD detection combined with SEM and TEM analysis confirms that the powders and ceramics are only composed of SDC and BCS phases, and no other phases are detected. The average diameter of the spherical core-shell structured SDC@xBCS powders is in 20–60 nm. A thin layer of BCS is coated on the surface of SDC in the synthesized SDC@BCS nanopowders, and a core-shell structure forms in the SDC@BCS composite ceramics. With the increase of the ratio of BCS:SDC from 1 to 1.5, the sample is more difficult to be densified. For x = 1, the sample of SDC@BCS achieves the highest electrical conductivity in four samples (x = 0, 0.5, 1, 1.5). At the test temperature of 600 °C, the electrical conductivity of the core-shell structured SDC@BCS ceramic (1:1) is higher than that of the common uniformly-mixed SDC-BCS samples, i.e., 1.545 × 10⁻² S/cm and 0.685 × 10⁻² S/cm in air and 10 %H₂–90 %N₂ atmosphere, respectively. At the same time, the specific grain boundary electrical conductivity of the core-shell structured SDC@BCS ceramics is also higher than that of uniformly mixed SDC-BCS composite ceramics. The construction of a core-shell structure can contribute to improving the electrical conductivity of the SDC-BCS composite ceramics.