Atomic resolution chemical bond analysis of oxygen in La2CuO4
Atomic resolution chemical bond analysis of oxygen in La2CuO4
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DOI：
10.1063/1.4819397
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发表时间：
2013-08-28
影响因子：
3.2
通讯作者：
Kimoto, K.
中科院分区：
文献类型：
--
作者：
Haruta, M.;Nagai, T.;Kimoto, K.
用原子分辨率的像差校正扫描透射电镜研究了La2CuO4中CuO6八面体的畸变。记录了氧k边电子能量损失谱中的近边结构是电子探针位置的函数。背景减除后，测量的光谱图像使用最近开发的反演过程进行处理，以消除原子柱上由于弹性和热散射引起的信号混合。然后将光谱与基于局域密度近似加现场库仑排斥（LDA + U）方法的第一性原理能带结构计算进行了比较。在本文中，我们不仅详细描述了氧2p态与Cu 3d态的各向异性化学键，而且还详细描述了氧2p态与Cu 4p态和La 5d/4f态的各向异性化学键。此外，在原子分辨率的氧k边也可以检测到CuO2平面的屈曲。最后，我们发现，在O - k边的核心孔的影响强烈依赖于局部化学键的性质，特别是，它是离子还是共价键。(C) 2013 AIP出版有限责任公司
The distorted CuO6 octahedron in La2CuO4 was studied using aberration-corrected scanning transmission electron microscopy at atomic resolution. The near-edge structure in the oxygen K-edge electron energy-loss spectrum was recorded as a function of the position of the electron probe. After background subtraction, the measured spectrum image was processed using a recently developed inversion process to remove the mixing of signals on the atomic columns due to elastic and thermal scattering. The spectra were then compared with first-principles band structure calculations based on the local-density approximation plus on-site Coulomb repulsion (LDA + U) approach. In this article, we describe in detail not only anisotropic chemical bonding of the oxygen 2p state with the Cu 3d state but also with the Cu 4p and La 5d/4f states. Furthermore, it was found that buckling of the CuO2 plane was also detectable at the atomic resolution oxygen K-edge. Lastly, it was found that the effects of core-hole in the O K-edge were strongly dependent on the nature of the local chemical bonding, in particular, whether it is ionic or covalent. (C) 2013 AIP Publishing LLC.