Zero-field and in-field Mössbauer spectroscopy as a tool for structural and magnetic characterization of maghemite (γ-Fe2O3) nanoparticles

Zbořil, Radek

doi:10.1007/s10582-005-0091-1

Cited by 10 publications

(6 citation statements)

References 76 publications

(63 reference statements)

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“…For the smallest concentration of iron acetate complex the spectrum consists of relatively broad singlet. It shows typical superparamagnetic behaviour for interacting particles at room temperature which agree with published results [8]. All nanoparticles in the sample (1 mmol) have relaxation times larger than the time scale of Mössbauer spectroscopy (i.e.…”

Section: Resultssupporting

confidence: 90%

Mössbauer Studies of Core-Shell Nanoparticles.

et al. 2011

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The ferrite magnetic nanoparticles with core-shell structures were obtained in two step preparation process. The Mössbauer spectra obtained for particles of pure maghemite or magnetite and two layered core-shell one the magnetite on maghemite and maghemite on magnetite are very different from each other. The presented results show that interparticle and intraparticle interaction plays important role in overall magnetic properties as well.

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Section: Resultssupporting

confidence: 90%

Mössbauer Studies of Core-Shell Nanoparticles.

et al. 2011

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“…We additionally have, however, a quite different method how to decide, whether the particles are in a superparamagnetic state -Mössbauer spectroscopy, as reviewed in detail for γ-Fe 2 O 3 nanoparticles in [7]. If the relaxation time given by (1) becomes comparable with the relevant time window of the Mössbauer effect, E84 A…”

Section: Introductionmentioning

confidence: 99%

Superparamagnetic properties of γ-Fe2O3 particles: Mössbauer spectroscopy and d.c. magnetic measurements

et al. 2006

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Particles of Fe oxide were prepared by chemical coprecipitation and their sizes were shown by TEM and confirmed by XRD to be in the range of 5 nm. The Mössbauer spectra at 120 K clearly indicated the absence of magnetite and presence of the maghemite (γ-Fe2O3) phase. We studied the transition of the system to superparamagnetic behaviour, which strongly depends on the relevant time window amounting to ∼ 10 −7 s for Mössbauer spectroscopy of 57 Fe and units of seconds for d.c. magnetic measurements. From the temperature dependences of magnetic moments of zero-field-cooled (ZFC)) and field-cooled (FC) samples, the distributions of blocking temperatures were determined. The comparison of the transition temperatures derived from these two types of measurements gave an independent estimate for the pre-exponential factor and the energy barrier and thus magnetocrystalline anisotropy in an order-of-magnitude agreement with the published data for bulk γ-Fe2O3.PACS : 61.46.Df, 75.30.Gw

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“…Common 300-K Mössbauer spectroscopy detected hematite in both samples, and magnetite and goethite in the Indian sample, but no maghemite. In-field Mössbauer spectroscopy would help detecting maghemite (Tuček and Zboril 2005). raman spectroscopy identified hematite in the overall bright parts of the martite grains and magnetite in small darker patches from both samples.…”

Section: Discussionmentioning

confidence: 99%

Micro- to nano-scale characterization of martite from a banded iron formation in India and a lateritic soil in Brazil

et al. 2014

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Indian crystals show trellis of subhedral magnetite hosting maghemite in sharp contact with interstitial hematite crystals, which suggests exsolution along parting planes. grain boundary migrations within the hematite point to dynamic crystallization during deformation. Dislocations and fluid inclusions in hematite reflect its precipitation related to a hydrothermal event. In the Brazilian martite, dislocations are observed and maghemite occurs as Insel structures and nano-twin sets. The latter, typical for the hematite, are a transformation product from maghemite into hematite. For both samples, a deformation-induced hydrothermally driven transformation from magnetite via maghemite to hematite is proposed. The transformation from magnetite into maghemite comprises intermediate non-stoichiometric magnetite steps related to a redox process. This study shows that martite found in supergene environment may result from earlier hypogene processes.

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Zero-field and in-field Mössbauer spectroscopy as a tool for structural and magnetic characterization of maghemite (γ-Fe2O3) nanoparticles

Cited by 10 publications

References 76 publications

Mössbauer Studies of Core-Shell Nanoparticles.

Mössbauer Studies of Core-Shell Nanoparticles.

Superparamagnetic properties of γ-Fe2O3 particles: Mössbauer spectroscopy and d.c. magnetic measurements

Micro- to nano-scale characterization of martite from a banded iron formation in India and a lateritic soil in Brazil

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