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

The crystal structure of a cubic Pm (3) over barm perovskite-type doped lanthanum cobaltite, La0.6Sr0.4CoO3-delta , has been studied using in situ neutron powder diffraction data measured at 1531 K. The refined occupancy 0.886 ( 6) of O atoms at the 3d 1/2, 0, 0 site indicated an oxygen deficiency of delta=0.34 ( 2) and an average valence of +2.7 for Co cations in La0.6Sr0.4CoO3-delta at 1531 K. Refined anisotropic atomic displacement parameters and nuclear density mapping reveal that the oxygen ions in La0.6Sr0.4CoO3-delta exhibit 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-delta is proposed, although it was not observed as a connected density in the experimental mapping.