Synchrotron X-ray Absorption Spectroscopy Study of Local Structure in Al-Doped BiFeO3 Powders

Autor: Jiaou Wang, Hai Jie Qian, Lirong Zheng, Turghunjan Gholam, Hui-Qiong Wang, Rui Wu
Rok vydání: 2019
Předmět:
Zdroj: Nanoscale Research Letters, Vol 14, Iss 1, Pp 1-12 (2019)
ISSN: 1556-276X
1931-7573
Popis: The Al-doped BiFeO3, i.e., BFA x O powder samples with x = 0, 0.025, 0.05, and 0.1, were prepared via the hydrothermal route. The effects of Al substitution on the structural, electrical, and optical properties of BFA x O samples were investigated. It is found that the substitution of Al ions at B-site of BiFeO3 did not cause structural change and it still retains the rhombohedral perovskite structure with R3c symmetry, which was confirmed by the X-ray diffraction (XRD) and Raman measurements. X-ray absorption fine structure (XAFS) above the Fe K-edge and Bi L 3-edge in BFA x O powders was also measured and analyzed. Fe ions exhibit mixed valence states (Fe2+/Fe3+) while Bi ions keep the + 3 valence state in all the samples. Fe K-edge XAFS also indicated that there was a competition between hybridization of Fe 3d and Al 3d with O 2p orbitals and occurrence of the more 4p orbitals with Al doping. The Bi L 3-edge XAFS revealed that transition from 2p 3/2 to 6d state increased, so did the energy of 6d state. Besides, Al ion doping affected both the nearest-neighbor and next-nearest coordination shells of Fe atom and nearest-neighbor shells of Bi atom. Ultraviolet-visible (UV-Vis) spectroscopy results show the BFA x O prepared by hydrothermal method could be an appropriate visible-light photocatalytic material.
Databáze: OpenAIRE
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