Vacancy Formation Energy in the Cubic Phase of Magnetite in the Framework of the DFT+U Method

Шутикова, М. И.; Stegaĭlov, V. V.

doi:10.1134/s1063776121080100

Cited by 7 publications

(24 citation statements)

References 46 publications

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“…1), which are free in the ideal cubic phase 32,33 . Our earlier results 28 confirm that the formation energy of a vacancy in the B-sublattice is lower than in the A-(or tetrahedral) sublattice. Calculations of the formation energies of iron interstitial atoms in the DFT+U framework is one of the tasks of this study.…”

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confidence: 80%

“…In this work, we present the results of the density functional theory calculations with the Hubbard correction (DFT+U 25,26 ) for the formation energies of vacancies and interstitials and compare the results with E f exp FP . Following Liu and Di Valentin 27 and our recent study 28 , we use the static DFT+U model of cubic magnetite without symmetry constraints on electron density that predicts the existence of a small band gap above T V that is in agreement with several experiments [29][30][31] .…”

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confidence: 52%

“…The use of the symmetry constraint on the electron density and the wave function in the DFT+U model of defect-free magnetite cubic phase is a problem of current interest 27,28 . It goes without saying that for defect magnetite such problem is not actual: a defect breaks lattice symmetry.…”

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confidence: 99%

“…The total energy convergence threshold for selfconsistent calculations and the forces-on-atoms convergence threshold for geometry optimizations are 10 −6 eV and 10 −2 eV/ Å respectively. The geometry optimization of the supercells with a defect and the atomic relaxation of defect-free supercells are performed at a fixed equilibrium lattice constant 20,21,28 . Equilibrium (zero pressure) lattice constants are obtained for the cubic phase of Fe 3 O 4 with the oxygen parameter x = 0.2549 (pressure has a strong influence on magnetite structure 39,40 ).…”

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confidence: 99%

“…A single pattern of charge-orbital ordering is considered, which has the lowest total energy (the case 'm2 -545' in 28 ).…”

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confidence: 99%

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Frenkel pair formation energy for cubic Fe$_3$O$_4$ in DFT+U calculations

Шутикова¹,

Stegaĭlov²

2022

Preprint

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Ab initio modelling of point defects in the cubic phase of magnetite faces two problems: the cubic structure becomes unstable below the Verwey temperature and there is no consensus on the electronic structure of the cubic phase (if there is a band gap, what type of symmetry of the wavefunction should be considered and how to describe strong electronic correlations). In this paper, we show that the comparison of the experimental data on the band gap and the Frenkel pair formation energy with the first-principles calculations allows to determine a consistent DFT+U model of cubic Fe3O4.

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supporting

confidence: 80%

mentioning

confidence: 52%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…A single pattern of charge-orbital ordering is considered, which has the lowest total energy (the case 'm2 -545' in 28 ).…”

mentioning

confidence: 99%

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Frenkel pair formation energy for cubic Fe$_3$O$_4$ in DFT+U calculations

Шутикова¹,

Stegaĭlov²

2022

Preprint

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High‐Temperature Oxidation of 60Si2Mn Spring Steel in Dry Air and Wet Air: Insights from an Experimental and First‐Principles Study

Zhao

Zhang

et al. 2023

steel research int.

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During the hot‐rolling process, the 60Si2Mn spring steel is exposed to both dry air and water vapor at high temperatures. However, no precise mechanism or theory is developed to explain the effect of water vapor on the oxide layer from a microscopic atomic perspective. The high‐temperature oxidation of 60Si2Mn spring steel with dry and wet air is investigated herein using a combination of experiments and first‐principles calculations. After high‐temperature oxidation in both dry and wet air, the 60Si2Mn spring steel generates a typical three‐layer structure consisting of Fe2O3, Fe3O4, and FeO + SiO2/Fe2SiO4; however, the oxide layer produced in wet air is significantly thicker. Furthermore, the phase transformation from Fe3O4 to Fe2O3 occurs in the middle Fe3O4 layer, which is associated with H protons derived from H2O molecules penetrating into oxide layers and promoting the development of Fe vacancies in the center of the tetrahedral interstices. The high porosity of the Fe3O4 layer essentially encourages Fe and O diffusion, hence enhancing the growth of the oxide layer and facilitating the transformation from Fe3O4 to Fe2O3. These findings provide a more detailed mechanistic explanation of how water vapor affects the high‐temperature oxidation of 60Si2Mn spring steel at the atomic level.

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