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

Anna Corrias*, Maria F. Casula, Andrea Falqui, Giorgio Paschina

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)3130-3138
Number of pages9
JournalChemistry of Materials
Issue number16
StatePublished - Aug 10 2004
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry


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