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Ferromagnetism Exhibited by Nanoparticles of Noble Metals

Maitra, Urmimala and Das, Barun and Kumar, Nitesh and Sundaresan, Athinarayanan and Rao, CNR (2011) Ferromagnetism Exhibited by Nanoparticles of Noble Metals. In: ChemPhysChem, 12 (12). pp. 2322-2327.

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Gold nanoparticles with average diameters in the range 2.515 nm, prepared at the organic/aqueous interface by using tetrakis( hydroxymethyl) phosphonium chloride (THPC) as reducing agent, exhibit ferromagnetism whereby the saturation magnetization M(S) increases with decreasing diameter and varies linearly with the fraction of surface atoms. The value of M(S) is higher when the particles are present as a film instead of as a sol. Capping with strongly interacting ligands such as alkane thiols results in a higher M(S) value, which varies with the strength of the metal-sulfur bond. Ferromagnetism is also found in Pt and Ag nanoparticles prepared as sols, and the M(S) values vary as Pt > Au > Ag. A careful study of the temperature variation of the magnetization of Au nanoparticles, along with certain other observations, suggests that small bare nanoparticles of noble metals could indeed possess ferromagnetism, albeit weak, which is accentuated in the presence of capping agents, specially alkane thiols which form strong metal-sulfur bonds.

Item Type: Journal Article
Publication: ChemPhysChem
Publisher: John Wiley & Sons
Additional Information: Copyright of this article belongs to John Wiley & Sons.
Keywords: gold;magnetic properties;nanoparticles;platinum;silver
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 30 Sep 2011 06:08
Last Modified: 30 Sep 2011 06:08
URI: http://eprints.iisc.ac.in/id/eprint/41010

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