Article ID Journal Published Year Pages File Type
5430254 Journal of Quantitative Spectroscopy and Radiative Transfer 2008 10 Pages PDF
Abstract

The morphology of WO3 aggregates formed by irregular nanoparticles (D∼40 nm) and nanowires of different aspect ratios (2, 4, 6, and 10 μm nominal lengths) dispersed in commonly used polar solvents without dispersant agents is investigated using a small-angle light scattering technique and by means of fractal theory. Nanoparticles form compact spherical aggregates (Df∼2.6), whereas 2 μm nanowires with low aspect ratio (L/D∼10) follow a slow cluster-cluster aggregation mechanism with no discernable change in fractal dimension (Df=2.1) monitored in an extended period of 6 months, despite a notable growth in size (Rg=2.3-3.1 μm). For higher aspect ratio nanowires, scattered intensity profiles, which migrate towards the Porod regime, qualitatively obey the Lorenz-Mie theory predictions. The 10 μm nanowires with very high aspect ratio (L/D∼250) are observed to form stable dispersions in a time span of 6 days. Analytical methods based on spherical primary particle formulations predict Df=1.9, 1.7, and 1.4 for 4, 6, and 10 μm nanowires, respectively.

Related Topics
Physical Sciences and Engineering Chemistry Spectroscopy
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