Preparation and electrical properties of double-doped perovskitestructured conducting ceramics Sm0.9Sr0.1Al1-xCoxO3-δ

Abstract

A series of new mixed-conducting ceramics Sm0.9Sr0.1Al1-xCoxO3-δ(SSAC, x=0.2, 0.4, 0.5, 0.6) with perovskite structure were prepared by sintering the precursor powders derived from organic gel process. The effects of sintering temperature and Co doping concentration on the crystal structure, phase composition and electrical properties were also discussed in detail. The X-ray diffraction results show that the over-high sintering temperature or Co doping content will lead to the formation of impure phase with a chemical formula of Sm(Sr)CoO3 in sinters, and the solid solubility limit of Co in this system lies in the range of 50 mol%—60 mol%. The partial substitution of Co for Al in Sm0.9Sr0.1Al1-xCoxO3-δ results in an increase in lattice volume. The measurement results of electrical properties reveal that the conductivities of SSAC ceramics are dominated by p-type conduction, and the conduction behavior conforms to the small polaron hopping transport mechanism. With the increasing sintering temperature, the conductivities of as-prepared samples gradually increase. For the SSAC ceramics with Co content lower than the solid solubility limit, it is observed that their conductivities increase with the increase of Co content while the corresponding apparent activation energies decrease. The prepared single-phase Sm0.9Sr0.1Al0.5Co0.5O3-δ ceramic body by sintering at 1200℃ for 10h has a conductivity of 63.4 S/cm and an apparent activation energy of 0.14eV. These novel SSAC mixed-conducting ceramics with good electrical properties can potentially be used in the field of high temperature electrochemistry.