Evolution of the structure and magnetic properties of FeCo nanoparticles in an alumina aerogel matrix

Corrias, A., Casula, M.F., Falqui, A., Paschina, G. (2004) Evolution of the structure and magnetic properties of FeCo nanoparticles in an alumina aerogel matrix. Chemistry of Materials, 16 (16). pp. 3130-3138. ISSN 0897-4756. (doi:10.1021/cm049796h) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Official URL
http://dx.doi.org/10.1021/cm049796h

Abstract

Nanocrystalline γ-Al2O3 and FeCo-Al 2O3 nanocomposite aerogels with high surface areas and pore volumes were prepared by high-temperature supercritical drying of alcogels obtained by a fast sol-gel procedure. The formation of γ-Al 2O3 occurs via a sequence of stages: in the parent aerogel an alkyl derivative of boehmite is observed whose calcination gives rise to a disordered phase and finally to γ-Al2O3 which is stable up to 1000 °C. In the presence of iron and cobalt, calcination of the aerogel gives rise to a spinel phase similar to γ-Al2O 3 where metal ions partially fill the vacancies. Nanocomposites constituted of FeCo alloy nanoparticles dispersed into γ-Al 2O3 matrix are obtained via reduction in hydrogen flow of the aerogels containing iron and cobalt. The amount and average size of the nanoparticles depends both on the temperature and time of the reduction treatment and affects the resulting magnetic properties. All the reduced aerogels show superparamagnetic behavior, but the collective magnetic properties are strongly dependent on the amount and mean size of the alloy nanoparticles.

Item Type: Article
DOI/Identification number: 10.1021/cm049796h
Uncontrolled keywords: Aerogels, Alloys, Calcination, Charged particles, Cobalt, Drying, Hydrogen, Magnetic properties, Nanostructured materials, Reduction, Sol-gels, Superparamagnetism, Alcogels, Disordered phase, Nanocomposite aerogels, Supercritical drying, Iron, article, crystallization, derivatization, evolution, gel, magnetic field, nanoparticle, particle size, phase separation, structure analysis, supercritical fluid, surface property
Subjects: Q Science > QC Physics > QC176.8.N35 Nanoscience, nanotechnology
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Anna Corrias
Date Deposited: 16 Dec 2014 15:20 UTC
Last Modified: 29 May 2019 13:56 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/46180 (The current URI for this page, for reference purposes)
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