Experimental Visualization of the Diffusional Pathway of Oxide Ions in a Layered Perovskite-type Cobaltite PrBaCo2O5+δ

Layered perovskite-type cobaltite PrBaCo2O5+delta is an oxide-ion and electronic mixed conductor with high oxide-ion conductivity and is promising for potential use in SOFC (solid oxide fuel cell) cathodes and oxygen membranes. The crystal structure and oxide-ion diffusional pathway of PrBaCo2O5+delta at 596 and 1000 degrees C have been investigated by in situ high-temperature neutron powder diffraction and a maximum-entropy method (MEM)-based nuclear-density analysis. The oxide ions of PrBaCo2O5+delta two-dimensionally and anisotropically diffuse through equatorial and deficient apical oxygen sites along the < 101 > directions in the Pr-Co-O ion-conducting slab.