The synthesis and some properties of Co, Ni, Zn, Cu, Mn and Cd substituted magnetites

Sidhu, P. S.; Gilkes, R. J.; Posner, A. M.

doi:10.1016/0022-1902(78)80418-7

Cited by 116 publications

(50 citation statements)

References 24 publications

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“…Chemical precipitation of highly crystalline particulate magnetite can be a spontaneous reaction (23). However, such chemical reactions are carried out at high temperatures, with ambient temperature reactions being slower and generally producing poor quality crystals (24).…”

Section: Discussionmentioning

confidence: 99%

Rapid magnetosome formation shown by real-time x-ray magnetic circular dichroism

Staniland

Ward

Harrison

et al. 2007

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

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Magnetosomes are magnetite nanoparticles formed by biomineralization within magnetotactic bacteria. Although there have been numerous genetic and proteomic studies of the magnetosomeformation process, there have been only limited and inconclusive studies of mineral-phase evolution during the formation process, and no real-time studies of such processes have yet been performed. Thus, suggested formation mechanisms still need substantiating with data. Here we report the examination of the magnetosome material throughout the formation process in a real-time in vivo study of Magnetospirillum gryphiswaldense, strain MSR-1. Transmission EM and x-ray absorption spectroscopy studies reveal that full-sized magnetosomes are seen 15 min after formation is initiated. These immature magnetosomes contain a surface layer of the nonmagnetic iron oxide-phase hematite. Mature magnetite is found after another 15 min, concurrent with a dramatic increase in magnetization. This rapid formation result is contrary to previously reported studies and discounts the previously proposed slow, multistep formation mechanisms. Thus, we conclude that the biomineralization of magnetite occurs rapidly in magnetotactic bacteria on a similar time scale to high-temperature chemical precipitation reactions, and we suggest that this finding is caused by a biological catalysis of the process.biomineralization ͉ magnetotactic bacteria ͉ biogenic magnetite ͉ ␣-hematite precursor

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Section: Discussionmentioning

confidence: 99%

Rapid magnetosome formation shown by real-time x-ray magnetic circular dichroism

Staniland

Ward

Harrison

et al. 2007

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

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“…Sidhu et aL (1978) showed that in aqueous systems, magnetite appeared to precipitate directly from solution. Formation of magnetite by interaction of Fe 2 § ions with 3,-FeOOH and by the oxidation of Fe(OH)2 also appears to involve dissolution of the initial solid phase (Schwertmann and Taylor, 1972;Tamaura et aL, 1981).…”

Section: Discussionmentioning

confidence: 99%

Effect of Cobalt on the Formation of Crystalline Iron Oxides from Ferrihydrite in Alkaline Media

Cornell

1989

Clays and clay miner.

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Abstract--At pH 12 Co-ferrihydrite transformed to either Co-goethite or Co-magnetite, the latter compound appearing at Co additions of > 18 mole %. Although Co was readily taken up by the magnetite structure, chemical analysis showed that no more than 7 mole % substitution of Co in goethite was achieved. Hematite formation was not strongly promoted by the presence of Co; with 9 mole % Co in the system, the amount of hematite relative to goethite in the product increased slightly. Co-substituted goethites grew as long, thin crystals. The presence of Co promoted some dendritic twinning of goethite. Cobalt retarded the transformation of ferrihydrite to more crystalline oxides mainly by stabilizing ferrihydrite against dissolution. A comparison of Co with divalent ions previously studied showed that their stabilizing ability decreases in the order Cu > Co > Mn, i.e., they follow the Irving-Williams series for the stability of metal complexes.

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“…Magnetite samples consisting of -0.1 /xm equant crystals ( Figure 1) were prepared by a precipitation technique (Sidhu et al, 1978). Magnetite was heated at 220~ for 3 hr to obtain maghemite of identical morphology.…”

Section: Preparation and Characterization Of Sarnplesmentioning

confidence: 99%

Dissolution of Iron Oxides and Oxyhydroxides in Hydrochloric and Perchloric Acids

Sidhu

Gilkes

Cornell

et al. 1981

Clays and clay miner.

210

120

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Abstract--The dissolution of synthetic magnetite, maghemite, hematite, goethite, lepidocrocite, and akaganeite was faster in HCI than in HCIO4. In the presence of H § the C1-ion increased the dissolution rate, but the 004-ion had no effect, suggesting that the formation of Fe-Cl surface complexes assists dissolution. The effect of temperature on the initial dissolution rate can be described by the Arrhenius equation, with dissolution rates in the order: lepidocrocite > magnetite > akaganeite > maghemite > hematite > goethite. Activation energies and frequency factors for these minerals are 20.0, 19.0, 16.0, 20.3, 20.9, 22.5 kcal/ mole and 5.8 • 1011, 1.8 • 101~ 7.4 • 10 7, 5.1 • 101~ 2.1 • 101~ 3.0 x 1011 g Fe dissolved/mZ/hr, respectively. The complete dissolution of magnetite, maghemite, hematite, and goethite is well described by the cube-root law, whereas that of lepidocrocite is not.

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The synthesis and some properties of Co, Ni, Zn, Cu, Mn and Cd substituted magnetites

Cited by 116 publications

References 24 publications

Rapid magnetosome formation shown by real-time x-ray magnetic circular dichroism

Rapid magnetosome formation shown by real-time x-ray magnetic circular dichroism

Effect of Cobalt on the Formation of Crystalline Iron Oxides from Ferrihydrite in Alkaline Media

Dissolution of Iron Oxides and Oxyhydroxides in Hydrochloric and Perchloric Acids

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