Metamagnetism of Siderite (FeCO3)

Jacobs, I. S.

doi:10.1063/1.1729389

Cited by 86 publications

(35 citation statements)

References 7 publications

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“…For the Ancora CIE bulk sample (Fig. 3 C and D), we also observe an inflection at around 37 K, which corresponds to the Neel temperature of siderite (33,34). We estimate the mass concentration of siderite of about 1-2 ‰.…”

Section: Resultsmentioning

confidence: 57%

Evidence for abundant isolated magnetic nanoparticles at the Paleocene–Eocene boundary

Wang

Kent

Jackson

2012

Proc. Natl. Acad. Sci. U.S.A.

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New rock magnetic results (thermal fluctuation tomography, highresolution first-order reversal curves and low temperature measurements) for samples from the Paleocene-Eocene thermal maximum and carbon isotope excursion in cored sections at Ancora and Wilson Lake on the Atlantic Coastal Plain of New Jersey indicate the presence of predominantly isolated, near-equidimensional single-domain magnetic particles rather than the chain patterns observed in a cultured magnetotactic bacteria sample or magnetofossils in extracts. The various published results can be reconciled with the recognition that chain magnetosomes tend to be preferentially extracted in the magnetic separation process but, as we show, may represent only a small fraction of the overall magnetic assemblage that accounts for the greatly enhanced magnetization of the carbon isotope excursion sediment but whose origin is thus unclear. T he Paleocene-Eocene boundary (∼55.8 Ma) is marked by an abrupt negative carbon isotope excursion (CIE) (1, 2) that coincides with an oxygen isotope decrease interpreted as the Paleocene-Eocene thermal maximum (PETM) (3). In a cored section at Ancora (AN) (Ocean Drilling Program Leg 174AX) on the Atlantic Coastal Plain of New Jersey (Fig. 1), a zone of anomalously high magnetic susceptibility was discovered coincident with the CIE at the base of the Manasquan Formation (now known as the Marlboro Clay) (4). Bulk sediment magnetic hysteresis measurements indicated that the high magnetization corresponds to an increased abundance of very fine-grained magnetite with single domain (SD)-like magnetic properties. A similar association of high concentration of SD magnetite in a kaolinite-rich interval with minimum carbon isotope values was subsequently found in two other drill cores (Clayton and Bass River), which with the Ancora site, formed a transect across the New Jersey Atlantic Coastal Plain (5). The average distance between the magnetic particles is estimated to be 20 times larger than their lengths, given a concentration of 100 parts per million (ppm) estimated from the bulk saturation magnetization. Attempts to image the magnetic grains by transmission electron microscopy (TEM) in a bulk sample from the CIE interval in the Clayton site resulted in finding only a handful of isolated grains, which nevertheless had the requisite nanoscale dimensions (∼50-70 nm) expected from the bulk hysteresis properties (5). Iron-rich nanophase material had been previously detected (with Mössbauer techniques) at several Cretaceous-Paleogene boundary sites and was ascribed to condensates from an impact ejecta plume (6, 7). Accordingly, the nanoparticle-rich interval associated with the CIE on the New Jersey Atlantic Coastal Plain was suggested to have a similar origin, providing circumstantial evidence for a major extraterrestrial (in this case cometary) impact at the onset of the CIE (5, 8).Anomalously high concentrations of SD-like material have been confirmed by subsequent studies of the CIE from the Atlantic Coastal Plain, making these C...

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Section: Resultsmentioning

confidence: 57%

Evidence for abundant isolated magnetic nanoparticles at the Paleocene–Eocene boundary

Wang

Kent

Jackson

2012

Proc. Natl. Acad. Sci. U.S.A.

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“…Applying a mathematical fit to this curve provides a quantitative analysis of the magnetic particle size distribution [23]. The resulting log-normal distribution can be seen figure 3d, with the values obtained for mean particle size and most probable particle size listed in table 1.…”

Section: Tem (N=200)mentioning

confidence: 98%

Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite byGeobacter sulfurreducens

et al. 2011

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The bioproduction of nano-scale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens, by adjusting the total biomass introduced at the start of the process.The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different 2 biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process.Relative cation distributions within the structure of the nanoparticles has been investigated by X-ray magnetic circular dichroism and indicates the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimised biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently in the less harmful trivalent form.

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“…Siderite is known to be antiferromagnetic below the Néel temperature of $38 K with the magnetic moments of Fe 2+ atoms oriented parallel to the [1 1 1] axis (e.g. Jacobs, 1963). Our calculations have been set up with this antiferromagnetic configuration.…”

Section: Structural and Vibrational Propertiesmentioning

confidence: 99%

Iron isotope fractionation between pyrite (FeS2), hematite (Fe2O3) and siderite (FeCO3): A first-principles density functional theory study

Blanchard

Poitrasson

Méheut

et al. 2009

Geochimica et Cosmochimica Acta

178

122

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Metamagnetism of Siderite (FeCO3)

Cited by 86 publications

References 7 publications

Evidence for abundant isolated magnetic nanoparticles at the Paleocene–Eocene boundary

Evidence for abundant isolated magnetic nanoparticles at the Paleocene–Eocene boundary

Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite byGeobacter sulfurreducens

Iron isotope fractionation between pyrite (FeS2), hematite (Fe2O3) and siderite (FeCO3): A first-principles density functional theory study

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