Structural investigation of the cubic perovskite-type doped lanthanum cobaltite La_0.6Sr_0.4CoO_3- at 1531 K: possible diffusion path of oxygen ions in an electrode material

The crystal structure of a cubic perovskite-type doped lanthanum cobaltite, La_0.6Sr_0.4CoO_3-, 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 = 0.34 (2) and an average valence of +2.7 for Co cations in La_0.6Sr_0.4CoO_3- at 1531 K. Refined anisotropic atomic displacement parameters and nuclear density mapping reveal that the oxygen ions in La_0.6Sr_0.4CoO_3- exhibit a large thermal motion perpendicular to the Co-O bond. A curved path for oxygen-ion migration between adjacent anion sites in La_0.6Sr_0.4CoO_3- is proposed, although it was not observed as a connected density in the experimental mapping.