Synthesis of La0.7Sr0.3Fe1-xMxO3 (M=Ni, Cu, A1 and Mn) as anode materials for solid oxide fuel cell

Abstract

The influence of Cu, Ni, Al and Mn doping at the B–site on the structure and properties of the perovskite oxide La0.7Sr0.3FeO3 was studied. These oxides were synthesized by the modified citrate method. The Cu, Al and Mn specimens showed homogeneous and single phase with cubic perovskite structure, except that Ni–doped specimens which showed single phase with tetragonal structure. The doped metals at the Fe site had significant effect on the crystallite size of La0.7Sr0.3FeO3 materials. The increase of doping amounts of Cu, Al and Mn caused a decrease in the crystallite size of La0.7Sr0.3FeO3 species. On the contrary, the crystallite size increased with the amount of Ni substituted at the Fe site. Reduction property was determined by Temperature–Programmed Reduction (TPR) technique. The result showed that the reduction process increased with the B site metal doping. The conductivity of La0.7Sr0.3FeO3 species was improved by Cu and Ni doping, especially 30% Ni doping that was the most effective quantity for enhancing the electrical conductivity of La0.7Sr0.3FeO3. At 750°C, the conductivity of La0.7Sr0.3Fe0.7Ni0.3O3 (650.5 S/cm) was about 3.8 times higher than that of undoped La0.7Sr0.3FeO3 (170 S/cm). In addition, thermal expansion coefficient of Ni-doped specimens increased with increasing Ni contents.