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Carbonization of solvent and capping agent based enhancement in the stabilization of cobalt nanoparticles and their magnetic study

Arora, Neha and Jagirdar, Balaji R (2012) Carbonization of solvent and capping agent based enhancement in the stabilization of cobalt nanoparticles and their magnetic study. In: JOURNAL OF MATERIALS CHEMISTRY, 22 (38). pp. 20671-20679.

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Official URL: http://dx.doi.org/10.1039/c2jm33712f

Abstract

We describe a hybrid synthetic protocol, the solvated metal atom dispersion (SMAD) method, for the synthesis and stabilization of monodisperse amorphous cobalt nanoparticles. By employing an optimized ratio of a weakly coordinating solvent and a capping agent monodisperse colloidal cobalt nanoparticles (2 +/- 0.5 nm) have been prepared by the SMAD method. However, the as-prepared samples were found to be oxidatively unstable which was elucidated by their magnetic studies. Oxidative stability in our case was achieved via a pyrolysis process that led to the decomposition of the organic solvent and the capping agent resulting in the formation of carbon encapsulated cobalt nanoparticles which was confirmed by Raman spectroscopy. Controlled annealing at different temperatures led to the phase transformation of metallic cobalt from the hcp to fcc phase. The magnetic behaviour varies with the phase and the particle size; especially, the coercivity of nanoparticles exhibited strong dependence on the phase transformation of cobalt. The high saturation magnetization close to that of the bulk value was achieved in the case of the annealed samples. In addition to detailed structural and morphological characterization, the results of thermal and magnetic studies are also presented.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the Royal Society of Chemistry
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Depositing User: Id for Latest eprints
Date Deposited: 31 Jan 2013 12:43
Last Modified: 31 Jan 2013 12:43
URI: http://eprints.iisc.ac.in/id/eprint/45301

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