LSM-YSZ Reactions in Different Atmospheres

The influences of the oxygen partial pressure and the LSM/YSZ ratio on the LSM-YSZ interface reactions at 1,000 °C were investigated. Both pellets and diffusion couples were employed in the study. The equilibrium thermodynamics of the LSM-YSZ reactions was clarified based on the pellet study-powder reaction. LSM reacts differently with YSZ in different atmospheres. In air, m-ZrO2 (monoclinic) is formed; while in N2, SrZrO3 and/or La2Zr2O7 are formed depending on the initial LSM/YSZ ratio. The reactions are reversible with varying P(O2) i.e. treating the sample in air after the heat treatment in N2 results in a decomposition of the formed La- and Sr-zirconates. The de-stabilisation of the LSM-YSZ interface under long-term annealing at 1,000 °C originates mainly from the inter-diffusion across the interface. Under reduced P(O2), the Mn diffusion from LSM into YSZ is enhanced. High P(O2) (0.21 atm) promotes the m-ZrO2 formation.