| A fuel cell is a device which can convert chemical energy directly to electric energy at a constant temperature. Because it is not limited by carnot cycle, it generates electricity in a high efficient and environmental friendly way. Furthermore, fuel is fed to the anode where it is oxidized and electrons are released to the external circuet.Solid Oixde Fuel Cell (SOFC), a kind of solid-only fuel cells which eliminates the problems that liquid electrolyte fuel cell face, is a promising fuel cell with many prominent advantages, such as no liquid, longevity. It becomes increasingly important to reduce the operation temperature of the fuel cells down to the range of 600 to 800℃. Howevers, there are significant barriers to intermediate temperature SOFC:electrolyte ohmic resistance and electrode overpotential, especially cathode overpotential. So a good performance cathode becomes the target. This thesis intends to reveal the property of cathode materials, aiming at developing practical intermediate temperatures SOFCs. The main work incudes the following dections:First, Ln0.5Sr0.5CoO3 samples was prepared and characterized. Hall coefficient and four-probe DC were exploited to investigate the carrier concentration, mobility and electrical conductivity, respectively. The results indicated that Ln0.5Sr0.5CoO3 (Ln=La,Pr) became perovskite polycrystalline thin films on YSZ substrate and LaAlO3 substrate when there sintered at 600℃, Ln0.5Sr0.5CoO3 thin film conductivity is bigger than Pr0.5Sr0.5CoO3 thin film, which is agreement with small-polaron conduction model in the adiabatic region by Emin and Holstein.Ln0.5Sr0.5CoO3 thin films carrier concentration and mobility became bigger with the temperature.And then, Synthetical Process and electrical properties of (La1-xPrx)2/3Sr1/3CoO3 were Studied. Sampies were tested by XRD,TG-DSC,XPS to investigate the carrier concentration, mobility and electrical conductivity, respectively. The results indicated that the sample became a perovskite phase at 1250℃. The maximum conductivity of the (La1-xPrx)2/3Sr1/3CoO3 (x=0.2,0.4,0.6,0.8) materials was shown at 973K.X-ray photon-electron spectroscopy (XPS)show that (La1-xPrx)2/3Sr1/3CoO3 the valences of Praseodymium in is +3 . There are two kinds of oxygen species, adsorption oxygen and lattice oxygen on (La1-xPrx)2/3Sr1/3CoO3 surface. Withing augmentation of Praseodymium,Crystal cell became small and bond force became strong. Oxygen became reduction. Co3+and Co4+ binding energy became descendence.
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