Study on the Conductivity of La0.4Sr1.6CoNbO6-δ As an Electrode Material for Symmetrical SOFC

The double-perovskite La0.4Sr1.6CoNbO6-δ(LSCN) powders were synthesized by the solid-state reaction method. The electrical conductivities of LSCN samples were tested in air and 5 vol%H2/Ar. The results show that the conductivity of LSCN in 5 vol%H2/Ar (8.12 Scm-1) at 850 °C was higher than that in air (7.03 Scm-1). The activation energy obtained from the Arrhenius function was 0.821 eV in air and 0.707 eV in 5 vol%H2/Ar. The analysis of XPS shows that there exit three valence states of Co (Co+2, Co+3, Co+4) and two of Nb (Nb+4, Nb+5). The loss of lattice oxygen in LSCN not only produces oxygen vacancies, but also generates excess electrons, which contributes to the electrical conductivity of the LSCN samples.