Evidence of charge ordering of Fe2+ and Fe3+ in magnetite observed by synchrotron X-ray anomalous scattering
Evidence of charge ordering of Fe2+ and Fe3+ in magnetite observed by synchrotron X-ray anomalous scattering
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同步加速器X射线反常散射观测到磁铁矿中Fe2和Fe3电荷有序性的证据
DOI：
10.2138/am-1999-0312
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发表时间：
1999
影响因子：
3.1
通讯作者：
S. Sasaki
中科院分区：
文献类型：
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作者：
T. Toyoda;Masahiko Tanaka;S. Sasaki
在Fe - K吸收边的x射线波长同步加速器异常散射实验使得在低温下区分磁铁矿中不同价态的离子成为可能。利用Fe2+和Fe3+异常散射因子的较大差异，应用价差对比法测量了磁铁矿在低温下的基阵反射和超晶格反射强度。在102 K下观测到半整数指数的反射，如0 4 7⁄2和4 4 9⁄2，表明磁铁矿转变为较低的对称形式。在102 K下的0 4 7 / 2超晶格反射中，在Fe - K边缘可以清楚地观察到衍射强度的能量依赖性。在E = 7.122 keV处，归一化强度的急剧最小值是由双电池上下部分的铁离子的价态对比来解释的。因此，我们的结果强烈表明，在低温下，磁铁矿中铁离子和铁离子之间存在电荷有序。
Abstract Synchrotron anomalous scattering experiments with X-ray wavelengths at the Fe K absorption edge have made it possible to distinguish between ions having different valence states in magnetite at low temperatures. Using a large difference in anomalous scattering factors between Fe2+ and Fe3+, the valence-difference contrast method was applied for the intensity measurements of fundamental and superlattice reflections of magnetite at low temperature. Reflections with half-integer indices, such as 0 4 7⁄2 and 4 4 9⁄2, were observed at 102 K, showing that magnetite transformed to a lower symmetry form. The energy dependence in the diffracted intensity was clearly observed at the Fe K-edge for the 0 4 7⁄2 superlattice reflection at 102 K. A sharp minimum of the normalized intensity at E = 7.122 keV was explained by the valence contrast between Fe ions occupied in the respective upper and lower parts of the double cell. Thus, our results strongly suggest the existence of charge ordering between ferrous and ferric ions in magnetite at low temperatures.
Satoshi Sasaki：“利用 X 射线异常散射进行价差对比度测量”J.Synch.Rad.（印刷中）。
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