Anti-Ferromagnetic Structure and Magnetic Properties of FeO with GGA+U+SOC Study

Yahi, N.; Azzaz, Y.; Ameri, M.; Benouis, M.; Bensaid, Djillali; Arbouche, O.; Yamani, M. El; Moulay, N.

doi:10.1134/s106378342003004x

Cited by 4 publications

(3 citation statements)

References 42 publications

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“…This indicates that the valence state of Fe is +3. 46,47 The spin magnetic moment of Fe in K−Fe/Beta-H is reduced to 3.51 μB. This reveals that there is electron transfer from K to Fe 3+ .…”

Section: Resultsmentioning

confidence: 91%

Insight into the Potassium Poisoning Effect for Selective Catalytic Reduction of NO_x with NH₃ over Fe/Beta

et al. 2021

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Alkali metal poisoning has been a complex yet unresolved issue restricting the catalytic activity of NH3–SCR catalysts in industry to date. Herein, the effect of K deposition on the catalytic activity of Fe/beta catalysts for NH3–SCR of NO x was systematically investigated by a series of experimental characterizations and density functional theory (DFT) calculations. It has been determined that a lower K deposition could activate and facilitate the transfer of electrons and enhance the ratio of Fe2+/Fe3+ and reducible Fe species, thereafter promoting the NO and O2 adsorption and decreasing the activation energy of NO to NO2, and thereby significantly improving the catalytic activity of 0.25% K–Fe/Beta. To the best of our knowledge, this phenomenon has not been reported in the field of exhaust abatement. Nevertheless, excessive K deposition (≥0.50%) can not only occupy the Brönsted acid sites, leading to perceptible aggregation of the active Fe species and an increase in the activation energy for NO oxidation on Lewis acid sites, but also induce the generation of inactive nitrates, blocking the pore structure of the Beta molecular sieve, resulting in the distinctive reduction of catalytic active Fe species, thereby seriously restricting the catalytic performances of 0.50% K–Fe/beta and 1.0% K–Fe/beta catalysts. Thus, this study may shine light on the deep understanding of alkali metal poison during NH3–SCR of NO x and the design of advanced catalysts in heterogeneous catalysis in the future.

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Section: Resultsmentioning

confidence: 91%

Insight into the Potassium Poisoning Effect for Selective Catalytic Reduction of NO_x with NH₃ over Fe/Beta

et al. 2021

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“…The samples measured at 5 K also exhibit the dependence on the magnetic field most likely coming from the magnetic properties of the FeO layer. The antiferromagnetic iron oxide (FeO) with the Néel temperature of 198 K − can be a source of additional scattering of electrons, leading to the reduction of differential resistance when compared to specimens measured at room temperature. The antiferromagnetic order can reduce the electrical conductivity due to the introduction of the energetic band gap, which causes inhibition of the charge carriers motion.…”

Section: Resultsmentioning

confidence: 99%

Manipulating Electrical Properties of Nanopatterned Double-Barrier Schottky Junctions in Ti/TiO_x/Fe Systems

Chojenka,

Zarzycki,

Perzanowski

et al. 2024

J. Phys. Chem. C

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This work characterizes the transport properties of double-barrier Schottky junctions with nanopatterned titanium oxide as a semiconductor. Nanoporous titanium oxide thin films with varying pore diameters are created by using electrochemical anodization. These films are then covered with a 50 nm thick iron layer, forming patterned Ti/TiO x /Fe junctions. SEM images confirm the nanoporous morphology of the titanium oxide, while XRD measurements show that the junctions are polycrystalline, with multiple phases of titanium oxide formed after annealing. UV−vis spectroscopy verifies the semiconducting nature of the titanium oxide, revealing a band gap of 2.3 eV. The I−V characteristics demonstrate nearly linear behavior, but deviations from Ohmic dependence occur when calculating the differential resistance. Interestingly, the pore diameter strongly influences the differential resistance at low temperatures. The magnetoresistance (MR) of the junctions exhibits different signs: positive values at room temperature and negative values at 5 K for all samples. Nanopatterning enhanced this effect. Detailed characterization uncovers that the positive MR originates from the titanium/titanium oxide interface, while the negative MR arises from the titanium oxide/iron interface regardless of temperature. The change in the MR sign is attributed to the different temperature dependences of the individual junctions, namely, Ti/TiO x and TiO x /Fe.

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“…Hubbard-U correction for oxygen was set for the first time in Fe 3 O 4 calculations, and the unit cell parameters of the three oxides achieved better results. The effects of two kinds of FeO spin magnetic orientation settings [ 25 , 26 ] are also discussed. The equation of state (EOS) curves under different pseudopotentials with the optimized parameters are calculated and compared.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Studies on the Atomistic Structure and Properties of Iron Oxides: A Parametric Study

Zhang

et al. 2022

Materials

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With the aim to find the best simulation routine to accurately predict the ground−state structures and properties of iron oxides (hematite, magnetite, and wustite) using density functional theory (DFT) with Hubbard-U correction, a significant amount of DFT calculations were conducted to investigate the influence of various simulation parameters (energy cutoff, K-point, U value, magnetization setting, smearing value, etc.) and pseudopotentials on the structures and properties of iron oxides. With optimized simulation parameters, the obtained equation of state, lattice constant, bulk moduli, and band gap is much closer to the experimental values compared with previous studies. Due to the strong coupling between the 2p orbital of O and the 3d orbital of Fe, it was found that Hubbard-U correction obviously improved the results for all three kinds of iron oxides including magnetite which has not yet been tested with U correction before, but the U value should be different for different oxides (3 ev, 4 ev, 4 ev for hematite, magnetite, and wustite, respectively). Two kinds of spin magnetism settings for FeO are considered, which should be chosen according to different calculation purposes. The detailed relationship between the parameter settings and the atomic structures and properties were analyzed, and the general principles for future DFT calculation of iron oxides were provided.

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Anti-Ferromagnetic Structure and Magnetic Properties of FeO with GGA+U+SOC Study

Cited by 4 publications

References 42 publications

Insight into the Potassium Poisoning Effect for Selective Catalytic Reduction of NO_x with NH₃ over Fe/Beta

Insight into the Potassium Poisoning Effect for Selective Catalytic Reduction of NO_x with NH₃ over Fe/Beta

Manipulating Electrical Properties of Nanopatterned Double-Barrier Schottky Junctions in Ti/TiO_x/Fe Systems

Density Functional Studies on the Atomistic Structure and Properties of Iron Oxides: A Parametric Study

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Anti-Ferromagnetic Structure and Magnetic Properties of FeO with GGA+U+SOC Study

Cited by 4 publications

References 42 publications

Insight into the Potassium Poisoning Effect for Selective Catalytic Reduction of NOx with NH3 over Fe/Beta

Insight into the Potassium Poisoning Effect for Selective Catalytic Reduction of NOx with NH3 over Fe/Beta

Manipulating Electrical Properties of Nanopatterned Double-Barrier Schottky Junctions in Ti/TiOx/Fe Systems

Density Functional Studies on the Atomistic Structure and Properties of Iron Oxides: A Parametric Study

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Insight into the Potassium Poisoning Effect for Selective Catalytic Reduction of NO_x with NH₃ over Fe/Beta

Insight into the Potassium Poisoning Effect for Selective Catalytic Reduction of NO_x with NH₃ over Fe/Beta

Manipulating Electrical Properties of Nanopatterned Double-Barrier Schottky Junctions in Ti/TiO_x/Fe Systems