Solid oxide fuel cell is a very attractive candidate for the future power generation system. The following materials are used in the state of the art SOFC: yttria-stabilized zirconia (YSZ) for electrolyte, La1-xSrxMn1±yO3-d for cathode, Ni-YSZ cermet for anode, and LaCrO3-based perovskites for interconnector. The instability of the cathode-electrolyte interface is one of the major disadvantages. It has been experimentally confirmed that some insulation phases, like SrZrO3 and La2Zr2O7, can be formed at the LSM-YSZ interface under certain conditions, and that the diffusion of Mn from LSM into YSZ plays a very important role. Numerous researches have been done to investigate this interface reaction. However, the mechanism is still not yet clarified.
A lot of efforts have been made in our group to model the reaction between La1-xSrxMn1±yO3-d and YSZ, using the CALPHAD method, and also to build a database of the La-Sr-Mn-Y-Zr-O system. In this paper, a thermodynamic description of the complete Mn-Y-Zr-O system is presented. The phase equilibria between YSZ and MnOx oxides under different temperatures and oxygen partial pressures are calculated. A very good represent of the experimental data was achieved in the present work. The solubilities of Mnx+ and other metal ions in cubic ZrO2 are also discussed.