Department of Materials and Chemistry, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka, 563-8577, Japan.
Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Kouto, Sayo-cho, Hyogo, 679-5198, Japan.
Sci Rep. 2018 Jan 11;8(1):415. doi: 10.1038/s41598-017-18847-0.
X-ray absorption near edge structure (XANES) measurement is one of the most powerful tools for the evaluation of a cation valence state. XANES measurement is sometimes the only available technique for the evaluation of the valence state of a dopant cation, which often occurs in phosphor materials. The validity of the core excitation process should be examined as a basis for understanding the applicability of this technique. Here, we demonstrate the validity of valence estimation of tin in oxide glasses, using Sn K-edge and L-edge XANES spectra, and compare the results with Sn Mössbauer analysis. The results of Sn K-edge XANES spectra analysis reveal that this approach cannot evaluate the actual valence state. On the contrary, in L-edge absorption whose transition is 2p-d, the change of the white line corresponds to the change of the valence state of tin, which is calculated from the Sn Mössbauer spectra. Among several analytical approaches, valence evaluation using the peak area, such as the absorption edge energy E at the fractions of the edge step or E at the zero of the second derivative, is better. The observed findings suggest that the valence state of a heavy element in amorphous materials should be discussed using several different definitions with error bars, even though L-edge XANES analyses are used.
X 射线吸收近边结构（XANES）测量是评估阳离子价态的最有力工具之一。XANES 测量有时是评估掺杂阳离子价态的唯一可用技术，这种情况经常发生在荧光材料中。为了理解该技术的适用性，应该检查核心激发过程的有效性。在这里，我们使用 Sn K 边和 L 边 XANES 光谱来证明氧化物玻璃中锡价态估计的有效性，并将结果与 Sn Mössbauer 分析进行比较。Sn K 边 XANES 光谱分析的结果表明，这种方法不能评估实际的价态。相反，在 2p-d 跃迁的 L 边吸收中，白线的变化对应于锡价态的变化，这是从 Sn Mössbauer 光谱计算得出的。在几种分析方法中，使用峰面积进行价态评估，例如边缘台阶的分数处的吸收边缘能量 E 或二阶导数为零时的 E ，效果更好。观察到的结果表明，即使使用 L 边 XANES 分析，也应该使用带有误差条的几个不同定义来讨论非晶态材料中重元素的价态。
