Preparation And Properties Of Doped Titanate Anode For Direct Oxidation Of Hydrocarbon Fuels In Solid Oxide Fuel Cells

Direct electrochemical oxidation of hydrocarbon fuels is the current development trend of SOFCs. Doped SrTiO3 is considered to be the potential anode material for SOFC because of its mixed ionic-electronic conductivities and excellent catalysis to hydrocarbon fuels. It is investigated with La substitution in A-site and Ga and Mn substitutions in B-site to improve its electrical properties.The calcinations process was investigated by DSC-TG. The optimal sintering temperature was investigated by DIL analysis. The structure of this material was characterized by means of XRD and SEM. The electrical performance was studied through a DC 4-probe method. The relative density and mechanical strength were also studied.The powders are fabricated by solid-state reaction at 1060℃for 2 h. After ball milling, drying and sieving, bars are shaped at 170 MPa, followed by isostatic pressing at 180 MPa. Samples are sealed into a crucible with carbon inside to create reducing atmospheres. They are sintered at 1360℃for 2 h. The main conclusions are as follows:The samples have a single perovskite phase. There is no chemical reaction between doped SrTiO₃ and 8YSZ sintered at 1400℃that showed good chemical compatibility.The composite is mixed oxygen-ionic/electronic conductor at 400℃ 900℃. It is electronic conductor at low temperatures and ionic conductor at high temperatures. The conductivity is related to the kind of dopant, its content and sintering temperature.The best properties are obtained for Sr_0.57La_0.29Ti_0.9Mn_0.05Ga_0.05O_2.95 sintered at 1360℃. Its conductivity reached 60.9 S/cm tested at 800℃. The relative density reached 96.6 % and the bending strength reached 128 MPa.