半导体
硫化
共价键
离子
材料科学
结晶学
八面体
化学
化学物理
光电子学
复合材料
晶体结构
有机化学
天然橡胶
作者
Lu Liu,Congmian Zhen,Lei Xu,Zizhou Shui,Li Ma,Dewei Zhao,Denglu Hou
标识
DOI:10.1016/j.jpcs.2022.111189
摘要
The effects of vulcanization on the electrical transport properties and magnetic structure of NiCo2O4 were studied in this work. NiCo2O4 films were epitaxially grown on Al2O3 substrate, and then vulcanized. The NiCo2O4 structures with O replaced by S atoms were calculated based on the density functional theory. As O were replaced by S atoms, the orbital overlap between S and cations increases, the localized electrons around cations are transformed into collective electrons, and the conductive behavior of the film changes from semiconductor to metal. The formation of covalent bonds caused by S substitution leads to the weakening of the interaction between tetrahedral Co and octahedral Ni ions. Meanwhile, the d-orbital energy level of cations shifts. The spin direction of Ni ions and half tetrahedral Co ions is flipped in the vulcanized NiCo2O4 structure, and the electrons at Ni3+ eg level enter the conduction band, which makes the carrier type of the vulcanized NiCo2O4 film change from p to n-type. These results indicate that S atoms play an active role in improving the conductivity of NiCo2O4.
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