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

Crystals

Chih-Hao Lee¹  Chia-Chin Chu¹  Aswin Kumar Anbalagan¹  Duc-Chau Nguyen²  Chia-Seng Chang² 

[1] Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan;Institute of Physics, Academia Sinica, Taipei 115, Taiwan;

关键词: perovskites;    Rietveld refinement;    EXAFS;    LaCoO₃;    X-ray absorption;    X-ray diffraction;   

DOI  :  10.3390/cryst12010050

来源: DOAJ

【 摘 要 】

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 La_1−xCe_xCoO₃, 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.

【 授权许可】

Unknown