ELECTRONIC-STRUCTURE OF COO, LI-DOPED COO, AND LICOO2
ELECTRONIC-STRUCTURE OF COO, LI-DOPED COO, AND LICOO2
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DOI：
10.1103/physrevb.44.6090
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发表时间：
1991-09-15
影响因子：
3.7
通讯作者：
TURNER, TS
中科院分区：
文献类型：
--
作者：
VANELP, J;WIELAND, JL;TURNER, TS
用X射线光电子能谱（XPS）、韧致辐射等色谱（BIS）和X射线吸收谱研究了Li（x）Co（1-x）O（0.01 ≤ x ≤ 0.2）、LiCoO 2和Co 3 O 4（1%Li）的电子结构。 实验结果与模型集群计算进行了比较。 我们发现，CoO的带隙是一个中间字符，Mott-Hubbard类和电荷转移类之间。 因此，第一电离态的CoO是强烈混合的Co 3d和O 2 p字符。 它的局部对称性对应于3 T1 g，类似于中间自旋Co 3+态。 对于x小于或等于0.2的本地Co的电子结构是类似的CoO。 然而，LiCoO 2具有强烈降低的Co-O原子间距离，导致配体场足够强以稳定Co 3+低自旋基态。 LiCoO 2是具有2.7 eV间隙的绝缘体。 从XPS和BIS CoO光谱的簇计算的比较，我们发现值为U（= 5.3 eV），DELTA（= 5.5 eV），和（Pd-sigma）（= 1.3 eV）。
The electronic structure of Li(x)Co(1-x)O (0.01 less-than-or-equal-to x less-than-or-equal-to 0.2), LiCoO2, and Co3O4(1% Li) has been investigated using x-ray photoemission spectroscopy (XPS), bremsstrahlung isochromat spectroscopy (BIS), and x-ray-absorption spectroscopy. The experimental results are compared with model cluster calculations. We find that the CoO band gap is of an intermediate character, between Mott-Hubbard-like and charge-transfer-like. The first ionization state of CoO is therefore of strongly mixed Co 3d and O 2p character. Its local symmetry corresponds to 3T1g, similar to an intermediate-spin Co3+ state. For x less-than-or-equal-to 0.2 the local Co electronic structure is similar to that of CoO. However, LiCoO2 has a strongly reduced Co-O interatomic distance, resulting in a ligand field strong enough to stabilize a Co3+ low-spin ground state. LiCoO2 is an insulator with a gap of 2.7 eV. From a comparison of the XPS and BIS CoO spectra to the cluster calculations, we find values for U (= 5.3 eV), DELTA (= 5.5 eV), and (pd-sigma) (= 1.3 eV).