Rietveld Refinement and X-ray Absorption Study on the Bonding States of Lanthanum-Based Perovskite-Type Oxides La1-xCexCoO3

Metal-oxygen bonding of the Ce-doped LaCoO3 system remains largely unexplored despite extensive studies on its magnetic properties. Here, we investigate the structure and local structure of nanoscale La1-xCexCoO3, with x = 0, 0.2, and 0.4, using the Rietveld refinement and synchrotron X-ray absorption techniques, complemented by topological analysis of experimental electron density and electron energy distribution. The Rietveld refinement results show that LaCoO3 subject to Ce addition is best interpretable by a model of cubic symmetry in contrast to the pristine LaCoO3, conventionally described by either a monoclinic model or a rhombohedral model. Ce4+/Co2+ are more evidently compatible dopants than Ce3+ for insertion into the main lattice. X-ray absorption data evidence the partially filled La 5d-band of the pristine LaCoO3 in accordance with the presence of La-O bonds with the shared-type atomic interaction. With increasing x, the increased Ce spectroscopic valence and enhanced La-O ionic bonding are noticeable. Characterization of the local structures around Co species also provides evidence to support the findings of the Rietveld refinement analysis.