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Nanocomposite powders by evaporation driven self assembly during spray drying: Some new insights on the structure evolution

Debasis Sen 1,2Olivier Spalla 1Antoine Thill 1Patrick Haltebourg 1

1. LIONS, SCM, CEA Saclay (LIONS), BAT 125, CEA Saclay, Gif sur Yvette, Gif-sur-Yvette 91191, France
2. Bhabha Atomic Research Centre (BARC), SSPD, Trombay, Mumbai, Mumbai 400085, India


Spray drying is an interesting process to synthesize nanocomposite powders of technological interests. However, structure and organization of the particles depend strongly on the thermodynamic/hydrodynamic conditions and interaction of the basic particles. Structural/compositional investigations on dried powders can reveal the mechanism of the organization during drying. In-situ scattering experiments can reveal such information. Small-angle X-ray scattering (SAXS) is a novel technique to investigate mesoscopic structure over a wide length scale. As volume fraction of droplets is not high enough to be probed in-situ by laboratory X-ray source, experiments at synchrotron source becomes essential. In-situ SAXS experiments on structural/correlation evolution of grains, during drying have been performed at ID2 beamline of European synchrotron radiation facility. An indigenously developed spray dryer has been used. Some salient results will be presented. In brief, depending on thermal gradiant of the tube, in intermediate drying stage, the arrest/drag of the nanocolloids at the droplet surface produces core-shell type grain with jammed particle concentration in shell and core with lower concentration. With the passage of droplets through thermal atmosphere, gradually the core also mimic the jammed concentration followed by the overall compression of initial droplet size. In addition, spray drying of mixed inorganic/organic colloids followed by post thermal treatments lead to production of porous nanopowders. The evolution of the structure, the correlation and the composition of such nanoporous powders [1] during the post thermal treatments will also be elaborated. [1] D. Sen, O. Spalla, L. Belloni, T. Charpentier, and A. Thill; Langmuir 22 3798-3806 (2006)


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Presentation: Oral at E-MRS Fall Meeting 2006, Symposium C, by Debasis Sen
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 15:44
Revised:   2009-06-07 00:44