Cu K-edge X-ray absorption spectroscopic (XAS) analyses have been systematically performed to examine the evolution of crystal and electronic structures of Sr2CuO3 upon fluorination. From the Cu K-edge X-ray absorption near-edge structure (XANES) results presented here, it becomes clear that the fluorination process leads to hole doping of the CuO2 layer as well as to structural modification from the square planar CuO4 cluster of Sr2CuO3 to the octahedral CuO4F2 one of Sr2CuO2F2+x. In addition, the comparative extended X-ray absorption fine structure (EXAFS) analyses for Sr2CuO2F2+x and the reference La2CuO4 reveal that the apical copper-ligand bond has a larger bond distance and a greater structural disorder in the former than in the latter. Based on these findings, it can be concluded that fluorine is preferentially incorporated into the apical site of CuO4F2 octahedra in Sr2CuO2F2+x. We suggest that this work can provide an excellent basis for the application of XAS to investigate the electronic and crystal structures of copper oxyhalides.
Bibliographical noteFunding Information:
The authors wish to acknowledge the financial support of Korea Research Foundation made in the program year of 1997. We thank also Prof. M. Nomura for his help in performing XAS measurement.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering