Nanoparticle aggregation and relaxation effects in ferrofluids studied through anisotropic light scattering

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Titre du document / Document title

Nanoparticle aggregation and relaxation effects in ferrofluids studied through anisotropic light scattering

Auteur(s) / Author(s)

RABLAU Corneliu⁽¹⁾ ; VAISHNAVA Prem⁽¹⁾ ; SUDAKAR Chandran⁽²⁾ ; TACKETT Ronald⁽²⁾ ; LAWES Gavin⁽²⁾ ; NAIK Ratna⁽²⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾Department of Physics, Kettering University, 1700 West Third Ave, Flint, MI, 48504, ETATS-UNIS
⁽²⁾Department of Physics and Astronomy, Wayne State University, Detroit, MI, 48201, ETATS-UNIS

Résumé / Abstract

We have investigated the aggregation and dissociation dynamics of 6-nm size Fe₃O₄ nanoparticles coated by tetra methyl ammonium hydroxide (TMAH) and the same size γ-Fe₂O₃ nanoparticles precipitated inside an alginate hydrogel matrix, both in aqueous suspensions, using dc magnetic-field-induced time-dependent light scattering patterns. For the Fe₃O₄ ferrofluid, a strong anisotropy in light scattering was observed for light propagating perpendicular to the magnetic field. This behavior is attributed to the aggregation of the nanoparticles into chain-like and column-like structures oriented parallel to the magnetic field. A significantly different behavior is observed for the aqueous suspension of γ-Fe₂O₃ nanoparticles precipitated in alginate hydrogel, for which the application of the dc magnetic field produced little to no change in the light scattering patterns. We attribute this difference to the constrained random distribution of γ-Fe₂O₃ nanoparticles precipitated in the alginate matrix. Correlating the results from this investigation with our previous study of magneto-thermal measurements in ac fields [Vaishnava et al., J. Appl. Phys. 102, 063914 (2007)], we conclude that for a ferrofluid to exhibit significant thermal effects under an ac magnetic field, it should exhibit optical anisotropy by developing a chain like structure under the influence of a dc magnetic field.

Revue / Journal Title

Proceedings of SPIE, the International Society for Optical Engineering ISSN 0277-786X CODEN PSISDG

Source / Source

Congrès
Plasmonics : ( metallic nanostructures and their optical properties VI ) ( 10-14 August 2008, San Diego, California, USA )
Plasmonics N^o6, San Diego CA , ETATS-UNIS (2008)
2008 , vol. 7032, pp. 70320Z.1-70320Z.12[Note(s) : 1 v. (various pagings), ] (33 ref.) ISBN 0-8194-7252-2 ; 978-0-8194-7252-6 ; Illustration : Illustration ;

Langue / Language

Anglais

Editeur / Publisher

Society of Photo-Optical Instrumentation Engineers, Bellingham, WA, ETATS-UNIS (1981) (Revue)
SPIE, Bellingham, Wash., ETATS-UNIS (2008) (Monographie)