Journal Article

PreJuSER-54004

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Thermal diffusion behavior of hard-sphere suspensions

Ning, H.FZJ* ; Buitenhuis, J.FZJ* ; Dhont, J. K. G.FZJ* ; Wiegand, S.FZJ*

2006
American Institute of Physics Melville, NY

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Please use a persistent id in citations: http://hdl.handle.net/2128/1214  http://hdl.handle.net/2128/2616  doi:10.1063/1.2400860

Abstract: We studied the thermal diffusion behavior of octadecyl coated silica particles (R(h)=27 nm) in toluene between 15.0 and 50.0 degrees C in a volume fraction range of 1%-30% by means of thermal diffusion forced Rayleigh scattering. The colloidal particles behave like hard spheres at high temperatures and as sticky spheres at low temperatures. With increasing temperature, the obtained Soret coefficient S(T) of the silica particles changed sign from negative to positive, which implies that the colloidal particles move to the warm side at low temperatures, whereas they move to the cold side at high temperatures. Additionally, we observed also a sign change of the Soret coefficient from positive to negative with increasing volume fraction. This is the first colloidal system for which a sign change with temperature and volume fraction has been observed. The concentration dependence of the thermal diffusion coefficient of the colloidal spheres is related to the colloid-colloid interactions, and will be compared with an existing theoretical description for interacting spherical particles. To characterize the particle-particle interaction parameters, we performed static and dynamic light scattering experiments. The temperature dependence of the thermal diffusion coefficient is predominantly determined by single colloidal particle properties, which are related to colloid-solvent molecule interactions.

Keyword(s): J

Note: Record converted from VDB: 12.11.2012

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Contributing Institute(s):

1. Weiche Materie (IFF-IWM)

Research Program(s):

1. Kondensierte Materie (P54)

Appears in the scientific report 2006
Notes: This version is available at http://dx.doi.org/10.1063/1.2400860 Copyright © American Institute of Physics

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