Structural investigation of the cubic perovskite-type doped lanthanum cobaltite La0.6Sr0.4CoO3−δat 1531 K: possible diffusion path of oxygen ions in an electrode material

The crystal structure of a cubic Pm 3 m perovskite-type doped lanthanum cobaltite, La0.6Sr0.4CoO3−δ, has been studied usingin situneutron powder diffraction data measured at 1531 K. The refined occupancy 0.886 (6) of O atoms at the 3d1/2, 0, 0 site indicated an oxygen deficiency of δ = 0.34 (2) and an average valence of +2.7 for Co cations in La0.6Sr0.4CoO3−δat 1531 K. Refined anisotropic atomic displacement parameters and nuclear density mapping reveal that the oxygen ions in La0.6Sr0.4CoO3−δexhibit a large thermal motion perpendicular to the Co—O bond. A curved path for oxygen-ion migration between adjacent anion sites in La0.6Sr0.4CoO3−δis proposed, although it was not observed as a connected density in the experimental mapping.