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Issue 9, 1989
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Crystallochemical characterization of magnetic spinels prepared from aqueous solution

Abstract

The crystallochemical characterization of magnetic spinels prepared from aqueous solution has been studied primarily by electron microscopy and 57Fe Mössbauer spectroscopy. Two synthetic routes have been investigated: method 1; partial oxidation of FeII solutions in the presence of NO3 at 100 °C, and method 2; reaction of hydrated FeIII oxide (ferrihydrite) with FeII ions at room temperature, pH = 7, 8 and 9. Both routes gave small (10–60 nm) irregular magnetite (Fe3O4) particles that were readily oxidised to maghemite (γ-Fe2O3). The reaction proceeded via a green-rust intermediate and anions such as inorganic phosphate (Pi) and SO2–4 reduced the rate of transformation. Spinel formation at room temperature was severely inhibited by Pi levels of 1 mol %, whereas 20–30 mol % Pi was required for retardation of crystallization at 100 °C. Intermediate levels (5–10 mole %) resulted in morphological enhancement of the octahedral crystal habit. A similar effect was observed in the presence of SO2–4 and at neutral pH in method 2.

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Article type: Paper
DOI: 10.1039/F19898503033
Citation: J. Chem. Soc., Faraday Trans. 1, 1989,85, 3033-3044
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    Crystallochemical characterization of magnetic spinels prepared from aqueous solution

    S. Mann, N. H. C. Sparks, S. B. Couling, M. C. Larcombe and R. B. Frankel, J. Chem. Soc., Faraday Trans. 1, 1989, 85, 3033
    DOI: 10.1039/F19898503033

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