Determination of valence state of Mn ions in Pr_1?xA_xMnO_3?¦Ä (A = Ca, Sr) by Mn-L₃ X-ray absorption near-edge structure analysis

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• 作者：Haruto Kanamori ; Tsuyoshi Yoshioka ; Kazuyuki Hirose ; Tomoyuki Yamamoto
• 关键词：Perovskite manganite ; X-ray absorption spectrum ; Valence state ; Magnetic property ; Electrical conductivity
• 刊名：Journal of Electron Spectroscopy and Related Phenomena
• 出版年：2012
• 出版时间：August, 2012
• 年：2012
• 卷：185
• 期：5-7
• 页码：129-132
• 全文大小：383 K

文摘

The valence states of the Mn ions in Pr_1?xA_xMnO_3?¦Ä (A = Ca, Sr) are investigated by Mn-L₃ X-ray absorption near-edge structure (XANES) analysis. The spectral fine structures in the Mn-L₃ XANES analysis show a significant difference between Pr_0.5Ca_0.5MnO_3?¦Ä and Pr_0.5Sr_0.5MnO_3?¦Ä, a paramagnetic insulator and a ferromagnetic metal, respectively, at room temperature, whereas the spectral structures of Pr_0.7Ca_0.3MnO_3?¦Ä and Pr_0.7Sr_0.3MnO_3?¦Ä, paramagnetic insulators, are almost identical. These results indicate that the valence states of the Mn ions in these materials are highly correlated with their magnetic and electrical properties. A significant difference was also found between the Mn-L₃ XANES profiles of Pr_1?xCa_xMnO_3?¦Ä and the profiles formed by the linear combination of the Mn-L₃ XANES spectra of PrMnO₃ (Mn³⁺) and CaMnO₃ (Mn⁴⁺). This difference indicates that the Mn ions in these materials do not have a mixed-valence state of 3+ and 4+, but have an intermediate valence state o 3+ and 4+.