Understanding the Mössbauer spectrum of magnetite below the Verwey transition:<i>Ab initio</i>calculations, simulation, and experiment

Řezníček, R.; Chlan, V.; Štěpánková, H.; Novák, P.; Żukrowski, J.; Kozłowski, A.; Ka̧kol, Z.; Tarnawski, Z.; Honig, J. M.

doi:10.1103/physrevb.96.195124

Cited by 21 publications

(26 citation statements)

References 36 publications

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“…Mössbauer spectra of the magnetite sample (MGP) at room temperature were in agreement with the data observed in several works ( Figure 1S) [47][48][49]. At room temperature, the magnetite spectrum showed two sextets derived from the sum of signals referring to two distinct iron sites on a magnetite structure.…”

Section: Discussionsupporting

confidence: 90%

“…Since the formation of the goethite phase can occur on the surface of the magnetite, the parameters of the second sextet (i.e., the outer octahedral layer) undergo major alterations, such as a slight decrease in B FH values. [40,47,48] Mössbauer parameters of the MGSCN sample showed a signal referring to the goethite mineral phase that was presented in the spectra as a sextet with isomeric shift at 0.39 mm s −1 and quadrupole splitting at −0.23. mm s −1 .…”

Section: Discussionmentioning

confidence: 98%

“…mm s −1 . This result is due to the formation of goethite crystals with small sizes, which generated differentiation in quadrupole splitting and hyperfine magnetic field parameters [40,47,48].…”

Section: Discussionmentioning

confidence: 99%

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Magnetite Synthesis in the Presence of Cyanide or Thiocyanate under Prebiotic Chemistry Conditions

Samulewski

Gonçalves

Urbano

et al. 2020

Life

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Magnetite is an iron oxide mineral component of primitive Earth. It is naturally synthesized in different ways, such as magma cooling as well as olivine decomposition under hydrothermal conditions. It is probable magnetite played a significant role in biogenesis. The seawater used in the current work contained high Mg2+, Ca2+ and SO42− concentrations, unlike the seawater of today that has high Na+ and Cl− concentrations. It is likely that this seawater better resembled the ion composition of the seas of the Earth from 4 billion years ago. Cyanide and thiocyanate were common molecules in prebiotic Earth, and especially in primitive oceans, where they could act on the magnetite mechanism synthesis via Fe2+ interaction. In this research, magnetite samples that were synthesized under prebiotic conditions in the presence of cyanide or thiocyanate, (both with and without artificial seawater), showed that, besides magnetite, goethite and ferrihydrite can be produced through different Fe2+-ion interactions. Cyanide apparently acts as a protective agent for magnetite production; however, thiocyanate and seawater 4.0 Gy ions produced goethite and ferrihydrite at different ratios. These results validate that Fe3+ oxides/hydroxides were possibly present in primitive Earth, even under anoxic conditions or in the absence of UV radiation. In addition, the results show that the composition of water in early oceans should not be neglected in prebiotic chemistry experiments, since this composition directly influences mineral formation.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 98%

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Magnetite Synthesis in the Presence of Cyanide or Thiocyanate under Prebiotic Chemistry Conditions

Samulewski

Gonçalves

Urbano

et al. 2020

Life

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“…The 24 different Fe atomic positions should result in the same number of sextets in a Mössbauer spectroscopy experiment, yielding spectra too complex for reliable analysis. However,Řezníček et al [30] have shown that these 24 sextets naturally break into four groups: eight FeA positions, eight less anisotropic FeB positions, five more anisotropic FeB positions, and three FeB sites with anisotropy comparable to the previous group yet with special orientation of the principal axes of the hyperfine field anisotropy tensor. Differences in parameters defining the sextets [hyperfine magnetic fields B eff , electric field gradient affecting quadrupole splitting (QS), and isomer shift (IS)] within these groups are too subtle to be revealed separately and the differences among these groups are relatively high.…”

Section: A Crystal Lattice Below T Vmentioning

confidence: 99%

“…Differences in parameters defining the sextets [hyperfine magnetic fields B eff , electric field gradient affecting quadrupole splitting (QS), and isomer shift (IS)] within these groups are too subtle to be revealed separately and the differences among these groups are relatively high. Consequently, only four groups were proposed to be important for the analysis, and this procedure was successfully applied in the interpretation of Mössbauer spectra in stoichiometric [30] and Zn-doped magnetite [11]. The same procedure will be used here, although it is strictly valid only in a zero external magnetic field [29], as discussed below.…”

Section: A Crystal Lattice Below T Vmentioning

confidence: 99%

Magnetic field induced structural changes in magnetite observed by resonant x-ray diffraction and Mössbauer spectroscopy

Kołodziej¹,

Bialo

Tabiś

et al. 2020

Phys. Rev. B

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When a magnetic field is applied to a single crystal of magnetite at 124 K > T > 50 K, the monoclinic c M axis, which is the easy magnetization axis, switches to one of the 100 cubic directions, nearest to the direction of the magnetic field, and the phenomenon known as an axis switching (AS) occurs. A global symmetry probe, resonant x-ray scattering, and a local probe, Mössbauer spectroscopy, are used to better understand the mechanism of axis switching. The behavior of three subsystems ordered below the Verwey transition temperature T V , i.e., lattice distortion, an orbital, and charge orderings, was observed via resonant x-ray scattering as a function of an external magnetic field. This was preceded by calculation of selected peak intensities using the FDMNES code. The Mössbauer spectroscopy studies confirmed that the magnetic field triggers electronic rearrangements and atomic displacements. The structure observed after the process of axis switching is very similar to the one obtained after cooling below T V with the magnetic field applied along one of the initial 100 cubic directions and distinct from the cooling in the absence of a magnetic field. From all the experimental observations of the phenomenon done so far, it is clear that AS starts from the fluctuations between octahedral iron orbitals that ultimately lead to the Verwey transition, but also to the higher-temperature trimeron dynamics. Therefore, further observation of the axis switching may be a key point to the understanding of a majority of strongly correlated electronic behavior in magnetite as well as in other transition metal oxides.

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Reverse‐Engineering Strain in Nanocrystallites by Tracking Trimerons

et al. 2021

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Although strain underpins the behavior of many transition‐oxide‐based magnetic nanomaterials, it is elusive to quantify. Since the formation of orbital molecules is sensitive to strain, a metal–insulator transition should be a window into nanocrystallite strain. Using three sizes of differently strained Fe3O4 polycrystalline nanorods, the impact of strain on the Verwey transition and the associated formation and dissolution processes of quasiparticle trimerons is tracked. In 40 and 50 nm long nanorods, increasing isotropic strain results in Verwey transitions going from TV ≈ 60 K to 20 K. By contrast, 700 nm long nanorods with uniaxial strain along the (110) direction have TV ≈ 150 K—the highest value reported thus far. A metal–insulator transition, like TV in Fe3O4, can be used to determine the effective strain within nanocrystallites, thus providing new insights into nanoparticle properties and nanomagnetism.

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Understanding the Mössbauer spectrum of magnetite below the Verwey transition:Ab initiocalculations, simulation, and experiment

Cited by 21 publications

References 36 publications

Magnetite Synthesis in the Presence of Cyanide or Thiocyanate under Prebiotic Chemistry Conditions

Magnetite Synthesis in the Presence of Cyanide or Thiocyanate under Prebiotic Chemistry Conditions

Magnetic field induced structural changes in magnetite observed by resonant x-ray diffraction and Mössbauer spectroscopy

Reverse‐Engineering Strain in Nanocrystallites by Tracking Trimerons

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