Theoretical analysis on O vacancy and cation inversion in NiCo2O4

•Two typical defects in NCO, O vacancy and cation inversion, were studied.•O vacancy introduces some energy levels, increasing chances of electron hopping.•O vacancy only affects the magnetic moment of the neighbor atoms.•Coordinated sites of metal ions affect their spin state and valence. We have i...

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Bibliographic Details
Published in:Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2021-01, Vol.263, p.114886, Article 114886
Main Authors: Wu, Chunfang, liu, Lu, Xu, Ruiping, Zhang, Kaiqi, Zhen, Congmian, Ma, Li, Hou, Denglu
Format: Article
Language:English
Subjects:
Band structures
Cation inversion
Cations
Density functional theory
Electron states
Electron transitions
Energy levels
Ferrimagnetism
Magnetic moments
Metal ions
Nickel compounds
NiCo2O4
Oxygen vacancy
Spin configuration
Transition metals
Vacancies
Valence band
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Summary:•Two typical defects in NCO, O vacancy and cation inversion, were studied.•O vacancy introduces some energy levels, increasing chances of electron hopping.•O vacancy only affects the magnetic moment of the neighbor atoms.•Coordinated sites of metal ions affect their spin state and valence. We have implemented polarized density function theory (DFT) on the transition metal d orbitals to explore the effects of oxygen vacancy and cation inversion on properties of NiCo2O4. The results show that NiCo2O4 has ferrimagnetic half-metallic ground states. Oxygen vacancy introduces additional energy levels in the majority spin band gap, which increases the chance of electron transition. In addition, O vacancy only affects the magnetic moment of the neighbor Oct Ni and Oct Co atoms. Calculations on NiCo2O4 with cation inversion confirms that coordinated sites of metal ions affect their spin state and valence, which further influence the conductivity and ferrimagnetic properties. The valence information of metal ions in NiCo2O4 was given. And the increased electron states in top of valence band make great contributions to p-type conductivity of NiCo2O4.
ISSN:0921-5107
1873-4944
DOI:10.1016/j.mseb.2020.114886