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Issue 4, 2007
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Reversible post-synthesis tuning of the superparamagnetic blocking temperature of γ-Fe2O3nanoparticles by adsorption and desorption of Co(ii) ions

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Abstract

The influence of the post-synthesis adsorption of Co(II) ions on the structural and magnetic properties of maghemite (γ-Fe2O3) nanoparticles with a mean particle size of about 10 nm has been investigated. It is shown that the step-wise adsorption of Co(II) can controllably increase the blocking temperature, TB, of the system up to 60 K with respect to that of untreated particles, while neither the particle size nor the particle size distribution are significantly modified. This is accompanied by a four-fold increase in the coercivity, HC, at low temperatures. Using a selective leaching of the previously adsorbed Co(II) ions the TB and HC values of the pristine γ-Fe2O3 nanoparticles are recovered. Hence, a reversible and controllable tailoring of the magnetic properties (e.g., TB and HC) of the γ-Fe2O3 nanoparticles can be achieved by a simple adsorption and desorption process of Co(II) ions after their synthesis.

Graphical abstract: Reversible post-synthesis tuning of the superparamagnetic blocking temperature of γ-Fe2O3 nanoparticles by adsorption and desorption of Co(ii) ions

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Article information


Submitted
08 Sep 2006
Accepted
19 Oct 2006
First published
02 Nov 2006

J. Mater. Chem., 2007,17, 322-328
Article type
Paper

Reversible post-synthesis tuning of the superparamagnetic blocking temperature of γ-Fe2O3 nanoparticles by adsorption and desorption of Co(II) ions

G. Salazar-Alvarez, J. Sort, A. Uheida, M. Muhammed, S. Suriñach, M. D. Baró and J. Nogués, J. Mater. Chem., 2007, 17, 322
DOI: 10.1039/B613026G

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