High-temperature thermal expansion and conductivity of cobaltites: potentials for adaptation of the thermal expansion to the demands for solid oxide fuel cells

Thermal expansion and conductivity measurements of LaCoO3−δ, EuCoO3−δ, Y1−xCoO3−δ and Y1−xCo1−yMnyO3−δ perovskites are presented and compared with magnetization and magnetic susceptibility data. An analysis by means of a phenomenological model reveals the importance of the spin state transition and its dependence on changes of the lattice structure in cobaltites. The influence of the insulator-to-metal transition at high temperature on the thermal expansion is also discussed. The potential of these compounds as cathodes for solid oxide fuel cells (SOFCs) is evaluated.