Effect of temperature on the porosity, microstructure, and properties of porous La0.8Sr0.2MnO3 cathode materials

Porous La0.8Sr0.2MnO3 cathode materials were prepared by the gelcasting technology. Carbon was employed to produce pores. It is shown that the open porosity decreases with increasing temperature. The proper sintering temperature is 1100 °C and the median pore size of the sample obtained at this temperature is about 460 nm. The microstructure indicates that the grain grows as the sintering temperature increases, which leads to the decrease of the number of open pores. Generally, the pores are located at multi-grain boundaries. Some closed pores appear in the sample prepared at 1100 °C and more. Both the conductivity and the interface bonding between La0.8Sr0.2MnO3 and YSZ get better as the temperature increases. When the sintering temperature is more than 1250 °C, La and Mn ions begin to diffuse into YSZ, and therefore interface reactions happen. According to ln(σT) ∼ 1/T curves, Ea was calculated to be 10.18 kJ/mol.