Searching for pure iron in nature: the Chelyabinsk meteorite

Leedahl, Brett; Королев, А. В.; Skornyakov, S. L.; Анисимов, В. И.; Белозеров, А. С.; Kukharenko, Andrey I.; Kurmaev, E.Z.; Гроховский, В. И.; Cholakh, S. O.; Moewes, A.

doi:10.1039/c6ra16598b

Cited by 11 publications

(8 citation statements)

References 34 publications

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“…The formation of strong arc discharge was also observed in other studies based on the analysis of discharge current and voltage [14,39] and the light emission signals due to arc discharge [42]. Fe 0 , Fe 2+ (FeO) and Fe 3+ (Fe2O3) [39,40] [29]. In addition to strong Fe-O-C bonding, the Fe and FeO nanoparticles may also link with the graphene films by other contact types, such as physisorption, electrostatic binding, covalent bond, and charge transfer interactions [29].…”

Section: Resultssupporting

confidence: 70%

“…1. The inset of Figure 6d shows the binding energy peaks of Fe 0 , Fe 2+ (FeO) and Fe 3+ (Fe 2 O 3 ) [39,40] in sample No.1; demonstrating the existence of Fe and FeO nanoparticles and partial oxidation of Fe nanoparticles in this sample. The presence of the Fe-O-C bond demonstrates that the graphene films have been anchored with Fe or FeO nanoparticles by Fe-O-C bonds.…”

Section: Resultsmentioning

confidence: 90%

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One Step Preparation of Fe–FeO–Graphene Nanocomposite through Pulsed Wire Discharge

et al. 2018

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The Fe-FeO-graphene nanocomposite material was produced successfully by pulsed wire discharge in graphene oxide (GO) suspension. Pure iron wires with a diameter of 0.25 mm and a length of 100 mm were used in the experiments. The discharge current and voltage were recorded to analyze the process of the pulsed wire discharge. The as-prepared samples-under different charging voltages-were recovered and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM). Curved and loose graphene films that were anchored with spherical Fe and FeO nanoparticles were obtained at the charging voltage of 8-10 kV. The present study discusses the mechanism by which the Fe-FeO-graphene nanocomposite material was formed during the pulsed wire discharge process.

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Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 90%

One Step Preparation of Fe–FeO–Graphene Nanocomposite through Pulsed Wire Discharge

et al. 2018

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“…The other sample (a1b) had not reached its Curie temperature by 1000 K, indicating a Ni‐poor FeNi phase (Leedahl et al. ); this sample also had a NRM intensity six times greater than the next strongest sample, and was one of the two samples for which HC and LC components were not identified. As stated above, sample a1b had a large chondrule near the surface.…”

Section: Resultsmentioning

confidence: 99%

Evidence for an impact‐induced magnetic fabric in Allende, and exogenous alternatives to the core dynamo theory for Allende magnetization

Muxworthy

Bland

Davison

et al. 2017

Meteorit & Planetary Scien

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Abstract-We conducted a paleomagnetic study of the matrix of Allende CV3 chondritic meteorite, isolating the matrix's primary remanent magnetization, measuring its magnetic fabric and estimating the ancient magnetic field intensity. A strong planar magnetic fabric was identified; the remanent magnetization of the matrix was aligned within this plane, suggesting a mechanism relating the magnetic fabric and remanence. The intensity of the matrix's remanent magnetization was found to be consistent and low (~6 lT). The primary magnetic mineral was found to be pyrrhotite. Given the thermal history of Allende, we conclude that the remanent magnetization was formed during or after an impact event. Recent mesoscale impact modeling, where chondrules and matrix are resolved, has shown that low-velocity collisions can generate significant matrix temperatures, as pore-space compaction attenuates shock energy and dramatically increases the amount of heating. Nonporous chondrules are unaffected, and act as heat-sinks, so matrix temperature excursions are brief. We extend this work to model Allende, and show that a 1 km/s planar impact generates bulk porosity, matrix porosity, and fabric in our target that match the observed values. Bimodal mixtures of a highly porous matrix and nominally zero-porosity chondrules make chondrites uniquely capable of recording transient or unstable fields. Targets that have uniform porosity, e.g., terrestrial impact craters, will not record transient or unstable fields. Rather than a core dynamo, it is therefore possible that the origin of the magnetic field in Allende was the impact itself, or a nebula field recorded during transient impact heating.

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“…The DFT alone, however, has difficulties in description of electron correlations, which in particular yield formation of local magnetic moments. The latter were shown to play an important role in iron [31][32][33][34][35][36][37][38] and its alloys [37][38][39][40]. An accurate treatment of local spin dynamics and many-body effects, which are especially relevant at finite temperatures, can be provided by a combination of DFT and dynamical mean-field theory (DMFT) [41,42].…”

Section: Introductionmentioning

confidence: 99%

Coulomb correlations and magnetic properties of L1$_0$ FeCo: a DFT+DMFT study

Belozerov,

Katanin,

Anisimov

2022

Preprint

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We consider electronic correlation effects and their impact on magnetic properties of tetragonally distorted chemically ordered FeCo alloy (L1 0 structure) being a promising candidate to rare-earthfree permanent magnets. We employ a state-of-the-art method combining the density functional (DFT) and dynamical mean-field theory (DMFT). According to our results, the predicted Curie temperature reduces with increase of lattice parameters ratio c/a and reaches nearly 850 K at c/a = 1.22. For all considered c/a from 1 to √ 2 we find well-localized magnetic moments on Fe sites, which are formed due to strong correlations originating from Hund's coupling. At the same time, magnetism of Co sites is more itinerant with a much less lifetime of local magnetic moments. However, these short-lived local moments are also formed due to Hund's exchange.Electronic states at Fe sites are characterized by non-quasiparticle form of self-energies, while the ones for Co sites are found to have a Fermi-liquid-like shape with quasiparticle mass enhancement factor m * /m ∼ 1.4, corresponding to moderately correlated metal. The strong electron correlations on Fe sites leading to Hund's metal behaviour can be explained by peculiarities of density of states, which has pronounced peaks near the Fermi level, while weaker many-body effects on Co sites can be caused by stronger deviation from half-filling of their 3d states. The obtained momentum dependence of magnetic susceptibility suggests that the ferromagnetic ordering is the most favourable one except for the near vicinity of the fcc structure and the magnetic exchange is expected to be of RKKY-type.

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Searching for pure iron in nature: the Chelyabinsk meteorite

Abstract: Herein we aimed to use thermomagnetic analysis (TMA) to determine the nature of iron and nickel in the Chelyabinsk meteorite, and their effect on the meteorite's magnetism.

Cited by 11 publications

References 34 publications

One Step Preparation of Fe–FeO–Graphene Nanocomposite through Pulsed Wire Discharge

One Step Preparation of Fe–FeO–Graphene Nanocomposite through Pulsed Wire Discharge

Evidence for an impact‐induced magnetic fabric in Allende, and exogenous alternatives to the core dynamo theory for Allende magnetization

Coulomb correlations and magnetic properties of L1$_0$ FeCo: a DFT+DMFT study

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