Orbital and spin contributions to magnetic hyperfine fields of the 3d transition metal ions

Ayuel, K.; Zakaria, Ahmed

doi:10.1016/j.jmmm.2018.02.044

Cited by 7 publications

(4 citation statements)

References 42 publications

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“…Given the ground-state electronic configuration of t 2g 4 e g 2 for the Fe 2+ ion in the octahedral crystal field, the unquenched orbital moment are expected from t 2g electrons, since the t 2g orbitals may be interconverted by rotation about a suitable axis . Similar orbital moments have been reported in other Fe 2+ -containing systems . The negative Weiss constant −5.892(1) K indicates extremely weak antiferromagnetic interaction among the Fe cations, which allows for the paramagnetism behavior down to 2 K. This is due to that FeO 6 octahedra are isolated in the shifted structure without direct Fe–Fe exchange nor Fe–O–Fe superexchange interaction.…”

Section: Resultssupporting

confidence: 52%

“…23 Similar orbital moments have been reported in other Fe 2+ -containing systems. 24 The negative Weiss constant −5.892(1) K indicates extremely weak antiferromagnetic interaction among the Fe cations, which allows for the paramagnetism behavior down to 2 K. This is due to that FeO 6 octahedra are isolated in the shifted structure without direct Fe−Fe exchange nor Fe−O− Fe superexchange interaction.…”

Section: ■ Introductionmentioning

confidence: 99%

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Shift–Twin Option in Eight-Layer Hexagonal Perovskite Niobates Ba₈MNb₆O₂₄

et al. 2020

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Two new eight-layer hexagonal perovskites with the composition Ba8MNb6O24 (M = Fe and Cu) are synthesized by solid-state reaction at 1350–1400 °C. Their crystal structures have been investigated using X-ray and electron diffractions as well as high-resolution transmission electron microscopy. Although both compounds have similar M2+ size, Ba8FeNb6O24 and Ba8CuNb6O24 adopt shifted and twinned structures, respectively. Through comparison with the reported shifted Ba8MNb6O24 (M = Mn, Co, and Zn) and twinned Ba8NiNb6O24 as well as inexistent Ba8Mg(Nb/Ta)6O24, we elucidate that the twin–shift competition of Ba8MNb6O24 family could be related with multiple chemical factors including tolerance factors, B-cationic size difference, entropy variation with B-cation and vacancy disorder, Jahn–Teller distortion, and FSO B–B d orbit interactions.

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Section: Resultssupporting

confidence: 52%

Section: ■ Introductionmentioning

confidence: 99%

Shift–Twin Option in Eight-Layer Hexagonal Perovskite Niobates Ba₈MNb₆O₂₄

et al. 2020

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“…Metal ions in coal samples catalyze the oxidative combustion process by reducing the activation energy and thereby promote spontaneous coal combustion. 34 Metal ions can control the spontaneous combustion of coal by activating hydrocarbon chains and initiating chain reactions. The addition of pre-oxidation and malic acid changes the catalytic activity of metal ions in the coal samples.…”

Section: Reaction Mechanismmentioning

confidence: 99%

DL‐malic acid for inhibiting the re‐ignition of long‐flame coal and its micro‐reaction mechanism

Bu,

Niu,

Wang

et al. 2024

Asia-Pacific J Chem Eng

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To study the metal ion chelating agent (DL‐malic acid) inhibiting oxidation characteristics of residual coal in goaf, the microscopic thermal transformation characteristics of the treated coal samples were obtained using apparent morphology, infrared spectroscopy, free radical testing, and thermal analysis. The results demonstrate that after the addition of malic acid, the sphericity and roundness of the coal samples decrease, and the small fractured particles accumulate in the pores of the oxidized coal samples and, thereby, reduce the number of coal–oxygen contact sites. The addition of 10% malic acid promotes the conversion of functional groups (FG) and free radicals in pre‐oxidized coal, inhibits the catalytic effect of metal ions, generates more active sites, and increases the total heat release during the combustion process. There are strong endothermic points in the malic acid‐treated coal samples, and the free water evaporation blocked by small particles in the holes delays the initial heat release temperature of the coal samples. Pre‐oxidation can promote changes in the valence state of metal ions in coal, increase the adhesion between broken pre‐oxidized coal particles via malic acid chelation, and lose the catalytic effect of metal ions; this inhibits the process of oxidative re‐ignition of coal samples.

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“…Copper complexes that have electronic absorption in the region of 20366 and 20202 cm −1 have 2 B 1g → 2 E 1g transitions and have a square planar geometry [24] [24]. The significantly higher moment magnetic of octahedral Co(II) complexes than that of spin-only value (μs, 3.87 BM) for three unpaired electrons is due to the orbital contribution to the magnetic moment [30][31]. The proposed structures of the Cu(II) and Co(II) complexes are shown in Fig.…”

Section: Uv-vismentioning

confidence: 99%

Novel Metal Coordination Complexes Based on 4-Aminophenol: Spectroscopic Analysis and Antibacterial Test

Syaima,

Rahardjo,

Hanifa

et al. 2023

Indones. J. Chem.

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The aims of this research are to synthesize and determine the formula, characteristics, and complex structure of Cu(II) and Co(II) with 4-aminophenol and to investigate their antibacterial activity. The complexes were synthesized by refluxing a solution of CuSO4·5H2O and CoSO4·7H2O, respectively, with 4-aminophenol in methanol for 1 h. The products were characterized using UV-Vis spectroscopy, atomic absorption spectroscopy, thermal analysis, conductivity, FTIR, and magnetic moment. The formation of the complex was indicated by shifting of maximum wavelength of the metal solution toward shorter, i.e., 817 to 421 nm for Cu(II) and 566 to 450 nm for Co(II). From the characterization, the proposed formulas of the complexes are [Cu(4-aminophenol)4]SO4 and [Co(4-aminophenol)4(H2O)2]SO4·5H2O forming square planar and octahedral geometry, respectively. Both complexes are paramagnetic with negligible antibacterial activity against Staphylococcus aureus, Staphylococcus epidermis, Escherichia coli, and Pseudomonas aeruginosa.

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Orbital and spin contributions to magnetic hyperfine fields of the 3d transition metal ions

Cited by 7 publications

References 42 publications

Shift–Twin Option in Eight-Layer Hexagonal Perovskite Niobates Ba₈MNb₆O₂₄

Shift–Twin Option in Eight-Layer Hexagonal Perovskite Niobates Ba₈MNb₆O₂₄

DL‐malic acid for inhibiting the re‐ignition of long‐flame coal and its micro‐reaction mechanism

Novel Metal Coordination Complexes Based on 4-Aminophenol: Spectroscopic Analysis and Antibacterial Test

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Orbital and spin contributions to magnetic hyperfine fields of the 3d transition metal ions

Cited by 7 publications

References 42 publications

Shift–Twin Option in Eight-Layer Hexagonal Perovskite Niobates Ba8MNb6O24

Shift–Twin Option in Eight-Layer Hexagonal Perovskite Niobates Ba8MNb6O24

DL‐malic acid for inhibiting the re‐ignition of long‐flame coal and its micro‐reaction mechanism

Novel Metal Coordination Complexes Based on 4-Aminophenol: Spectroscopic Analysis and Antibacterial Test

Contact Info

Product

Resources

About

Shift–Twin Option in Eight-Layer Hexagonal Perovskite Niobates Ba₈MNb₆O₂₄

Shift–Twin Option in Eight-Layer Hexagonal Perovskite Niobates Ba₈MNb₆O₂₄