Jump to main content
Jump to site search

Issue 5, 2009
Previous Article Next Article

Nanocrystalline Co30Fe70 alloy synthesized by alkalide reduction

Author affiliations


Co30Fe70 nanocrystallites have been synthesized by alkalide co-reduction of Co2+ and Fe3+. As produced, the material consists of highly pyrophoric 4.0 nm nanocrystals with a narrow (<12%) size distribution, that are superparamagnetic with an average blocking temperature <TB> of ∼20 K prior to removal of the by-products in which they are embedded. Removal of the by-products allows magnetic interactions between the particles with a consequent increase in the transition temperature to greater than 300 K. Annealing at temperatures higher than 300 °C under vacuum resulted in agglomeration and particle growth; annealing above 500 °C resulted in a change in the shape of the particles to largely rectangular prisms with little further growth above 700 °C. Ms increased with increasing annealing temperature reaching values as large as ∼89% of the bulk value (245 emu/g) after annealing at 700 °C while retaining low Mr and Hc. While rapid exposure of the Co30Fe70 nanocrystallites to air resulted in spontaneous combustion, gradual, slow exposure over a period of one week resulted in the formation of a thin surface coating of CoFe2O4, or air stable “core-shell” alloy–oxide nanocrystallites.

Graphical abstract: Nanocrystalline Co30Fe70 alloy synthesized by alkalide reduction

Back to tab navigation

Publication details

The article was received on 09 Sep 2008, accepted on 30 Oct 2008 and first published on 10 Dec 2008

Article type: Paper
DOI: 10.1039/B815751K
Citation: J. Mater. Chem., 2009,19, 611-616
  •   Request permissions

    Nanocrystalline Co30Fe70 alloy synthesized by alkalide reduction

    K. E. Mooney and M. J. Wagner, J. Mater. Chem., 2009, 19, 611
    DOI: 10.1039/B815751K

Search articles by author