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Single crystalline magnetite, maghemite, and hematite nanoparticles with rich coercivity

Dar, Ibrahim M and Shivashankar, SA (2014) Single crystalline magnetite, maghemite, and hematite nanoparticles with rich coercivity. In: RSC ADVANCES, 4 (8). pp. 4105-4113.

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Official URL: http://dx.doi.org/10.1039/c3ra45457f

Abstract

One-pot synthesis of amorphous iron oxide nanoparticles with two different dimensions (<5 nm and 60 nm) has been achieved using the reverse micelle method, with <5 nm nanoparticles separated from the stable colloid by exploiting their magnetic behaviour. The transformation of the as-prepared amorphous powders into Fe3O4 and Fe2O3 phases (gamma and alpha) is achieved by carrying out controlled annealing at elevated temperatures under different optimized conditions. The as-prepared samples resulting from micellar synthesis and the corresponding annealed ones are thoroughly characterized by powder X-ray diffraction, transmission electron microscopy (TEM), and by Raman and X-ray photoelectron spectroscopies. Expectedly, the magnetic characteristics of Fe3O4 and Fe2O3 phase (gamma and alpha) nanoparticles are found to have strong dependence on their phase, dimension, and morphology. The coercivity of Fe3O4 and Fe2O3 (gamma and alpha) nanoparticles is reasonably high, even though high resolution TEM studies bring out that these nanoparticles are single crystalline. This is in contrast with previous reports wherein poly-crystallinity of iron oxides nanoparticles has been regarded as a prerequisite for high coercivity.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the ROYAL SOC CHEMISTRY ENGLAND
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Division of Interdisciplinary Research > Centre for Nano Science and Engineering
Depositing User: Id for Latest eprints
Date Deposited: 06 Feb 2014 06:10
Last Modified: 06 Feb 2014 06:10
URI: http://eprints.iisc.ac.in/id/eprint/48317

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