Determination of Elemental Ratio in an Atomic Column by Electron Energy Loss Spectroscopy
Determination of Elemental Ratio in an Atomic Column by Electron Energy Loss Spectroscopy
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DOI：
10.1021/acsnano.6b01887
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发表时间：
2016-07-01
期刊：
影响因子：
17.1
通讯作者：
Kurata, Hiroki
中科院分区：
文献类型：
--
作者：
Haruta, Mitsutaka;Hosaka, Yoshiteru;Kurata, Hiroki
利用电子能量损失谱结合像差校正扫描透射电子显微镜测定了八面体和四面体Ca2Fe1.07Mn0.93O5中Fe与Mn元素比的原子分辨率定量。综合技术表明，光谱成像数据的过采样产生了一个空间分辨区域，非常接近原子分辨率（类似于1.2埃半径）。在该区域内的Fe与Mn的平均实验比率对于八面体位点为17.5：82.5，对于四面体位点为81.6：18.4。通过估计最近邻柱信号的混合，成功地提取了八面体原子柱中的元素比。结果表明，在八面体位置上，Fe与Mn的比例为13：87，这与中子衍射分析结果相一致。此外，通过使用平均1.2埃半径获得的实验结果的不确定性小于10%，在八面体网站，取决于样品的厚度。与此相反，由于入射电子的退散的实验误差较大的四面体网站。该实验方法在确定类钙钛矿化合物中元素的空间分辨组成比方面具有广泛的应用。
Atomic-resolution quantification of the elemental ratio of Fe to Mn at the octahedral and tetrahedral sites in brownmillerite Ca2Fe1.07Mn0.93O5 was determined using electron energy-loss spectroscopy combined with aberration-corrected scanning transmission electron microscopy. The combined techniques revealed that oversampling of the spectral imaging data yielded a spatially resolved area that very nearly reflects atomic resolution (similar to 1.2 angstrom radius). The average experimental ratios of Fe to Mn within this region were 17.5:82.5 for the octahedral sites and 81.6:18.4 for the tetrahedral sites. The elemental ratio in an octahedral atomic column was successfully extracted by estimating the mixing of signals from nearest neighbor columns. The results indicated that the ratio of Fe to Mn was 13:87 at the octahedral site, which is in good agreement with the results of neutron diffraction analysis. In addition, the uncertainty of experimental results obtained by using an average 1.2 angstrom radius was less than 10% at octahedral sites, depending on the sample thickness. In contrast, the experimental error due to dechanneling of incident electrons was larger at the tetrahedral sites. This experimental procedure has wide application for determining the spatially resolved composition ratio of elements in perovskite-like compounds.