Probing the Ba 5d states in BaTiO₃ and BaSO₄: A resonant x-ray emission study at the Ba-L₃ edge

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• 作者：Kenji Yoshii^a ; ^{yoshiike@spring8.or.jp} ; Ignace Jarrige^a ; Chikashi Suzuki^b ; Daiju Matsumura^a ; Yasuo Nishihata^a ; Yasuhiro Yoneda^a ; Tatsuo Fukuda^a ; Kazuhisa Tamura^a ; Yoshiaki Ito^c ; Takeshi Mukoyama^c ; Tatsunori Tochio^d ; Hiroshi Shinotsuka^e ; Sei Fukushima^e
• 关键词：A. Oxides ; C. Ab initio calculations ; C. XAFS (EXAFS and XANES) ; D. Electronic structure
• 刊名：Journal of Physics and Chemistry of Solids
• 出版年：2012
• 期刊代码：69_00223697
• 类别：ch
• 出版时间：September, 2012
• 卷：73
• 期：9
• 页码：1106-1110
• 文件大小：328 K

摘要

We have directly probed the Ba 5d states in the ferroelectric barium titanate BaTiO₃ using two bulk-sensitive spectroscopic probes, resonant x-ray emission spectroscopy (RXES) and x-ray absorption spectroscopy in the partial fluorescence mode (PFY-XAS) at the Ba-L₃ edge. The results are compared with those of the non-ferroelectric barium sulfate BaSO₄. While the RXES spectra point to a localized character for the Ba 5d states in both compounds, the main peak of the PFY-XAS spectrum, corresponding to the dipolar transitions from 2p to 5d, is found to be significantly broader for BaTiO₃ than for BaSO₄. On the basis of band structure calculations, this broadening is ascribed to strong hybridization between the unoccupied Ba 5d and O 2p states in the ferroelectric. This suggests that the hybridization between the conduction states of the Ba²⁺ and O^{2鈭?/sup> ions, and not only Ti4+ and O2鈭?/sup>, plays a central role in determining the electronic structure of BaTiO₃, and is therefore likely to be indirectly correlated with the occurrence of ferroelectricity in this material.}