X-ray emission spectroscopy: an effective route to extract site occupation of cations
X-ray emission spectroscopy: an effective route to extract site occupation of cations
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DOI：
10.1039/c8cp04628j
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发表时间：
2018-12-14
影响因子：
3.3
通讯作者：
Robinson, Richard D.
中科院分区：
文献类型：
--
作者：
Bhargava, Anuj;Chen, Cindy Y.;Robinson, Richard D.
阳离子位置占据是材料性质的重要决定因素，特别是在具有多个阳离子的复杂系统中，例如在三元尖晶石中。过去已经探索了许多用于提取阳离子位点信息的方法，包括通过K边X射线吸收光谱（XAS）获得的光谱的分析。在这项工作中，我们测量的有效性，X射线发射光谱（XES）确定阳离子位点的占领。作为测试系统，我们使用被CoO相污染的尖晶石相CoxMn 3-xO 4纳米颗粒，因为Co和Mn可以占据所有阳离子位点，并且杂质模拟氧化物合成的典型产物。我们利用的自旋和氧化态敏感的K β（1，3）峰使用XES得到的，并证明XES是一个强大的和可靠的技术，用于确定现场占领在三元尖晶石系统。扩展X射线吸收精细结构（EXAFS）和XES技术之间的比较表明，XES不仅提供了网站的EXAFS占据信息，但也在每个网站上的阳离子的氧化态的额外信息。我们表明，EXAFS的误差可高达35%，这使得某些化学计量的结果不明确，而对于XES，确定的误差始终小于10%。因此，我们得出结论，XES是一个上级和更准确的方法比XAS在提取阳离子占位尖晶石晶体结构。
Cation site occupation is an important determinant of materials properties, especially in a complex system with multiple cations such as in ternary spinels. Many methods for extracting the cation site information have been explored in the past, including analysis of spectra obtained through K-edge X-ray absorption spectroscopy (XAS). In this work, we measure the effectiveness of X-ray emission spectroscopy (XES) for determining the cation site occupation. As a test system we use spinel phase CoxMn3-xO4 nanoparticles contaminated with CoO phases because Co and Mn can occupy all cation sites and the impurity simulates typical products of oxide syntheses. We take advantage of the spin and oxidation state sensitive K beta(1,3) peak obtained using XES and demonstrate that XES is a powerful and reliable technique for determining site occupation in ternary spinel systems. Comparison between the extended X-ray absorption fine structure (EXAFS) and XES techniques reveals that XES provides not only the site occupation information as EXAFS, but also additional information on the oxidation states of the cations at each site. We show that the error for EXAFS can be as high as 35% which makes the results obtained ambiguous for certain stoichiometries, whereas for XES, the error determined is consistently smaller than 10%. Thus, we conclude that XES is a superior and a far more accurate method than XAS in extracting cation site occupation in spinel crystal structures.