Chang Tzu-Chien, Lu Yi-Ting, Lee Chih-Heng, Gupta Jyoti K, Hardwick Laurence J, Hu Chi-Chang, Chen Hsin-Yi Tiffany
Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300044, Taiwan.
Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300044, Taiwan.
ACS Omega. 2021 Mar 30;6(14):9692-9699. doi: 10.1021/acsomega.1c00295. eCollection 2021 Apr 13.
In this study, electronic structure calculations and Bader charge analysis have been completed on the inverse, intermediate, and normal spinel structures of NiCoO in both primitive and conventional cells, using density functional theory with Hubbard correction. Three spinel structures have been computed in the primitive cell, where the fully inverse spinel, 50% intermediate spinel, and normal spinel can be acquired by swapping Ni and Co atoms on tetrahedral and octahedral sites. Furthermore, NiCoO with different degrees of inversion in the conventional cells was also investigated, along with their doping energies. Confirmed by the assigned formal charges, magnetic moments, and decomposed density of state, our results suggest that the electronic properties of Ni and Co on the tetrahedral site can be altered by swapping Ni and Co atoms, whereas both Ni and Co on the octahedral site are uninfluenced. A simple and widely used model, crystal field theory, is also compared with our calculations and shows a consistent prediction about the cation distribution in NiCoO. This study analyzes the correlation between cation arrangements and formal charges, which could potentially be used to predict the desired electronic properties of NiCoO for various applications.
在本研究中，使用含哈伯德修正的密度泛函理论，对原始晶胞和常规晶胞中NiCoO的反尖晶石结构、中间尖晶石结构和正常尖晶石结构进行了电子结构计算和巴德电荷分析。在原始晶胞中计算了三种尖晶石结构，通过在四面体和八面体位置交换Ni和Co原子可得到完全反尖晶石、50%中间尖晶石和正常尖晶石。此外，还研究了常规晶胞中不同反演程度的NiCoO及其掺杂能。通过指定的形式电荷、磁矩和态密度分解得到证实，我们的结果表明，通过交换Ni和Co原子可以改变四面体位置上Ni和Co的电子性质，而八面体位置上的Ni和Co均不受影响。还将一个简单且广泛使用的模型——晶体场理论与我们的计算进行了比较，该理论对NiCoO中的阳离子分布给出了一致的预测。本研究分析了阳离子排列与形式电荷之间的相关性，这可能有助于预测NiCoO在各种应用中所需的电子性质。
