Crystal growth through progressive densification identified by synchrotron small-angle x-ray scattering
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Date
2008-05
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American Chemical Society
Abstract
For the first time, evolution of the interfacial structure of aluminum hydroxide nuclei forming within concentrated caustic solutions has been examined in situ in real time. In both dilute and concentrated caustic aluminate solutions (NaOH = 1.0 and 3.0 M, respectively, [NaOH]/[Al] = 1.22), the measured synchrotron small-angle X-ray scattering data indicate distinctly different surface structures throughout the maturation process. In the dilute solution, the data are consistent with a thin layer of less dense, recently accreted material on the surface of large fully dense particles-consistent with the familiar model process of species attachment to well-faceted surfaces. In contrast to this, the data for the concentrated solution are consistent with large diffuse particles growing with a mass fractal dimension of approximately 2.5 which density to form rough surface fractal particles on maturation. This unusual densification crystallization mechanism may occur in analogous concentrated systems where the fractal structures may be entropically stablized. © 2008, American Chemical Society
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Keywords
Aluminium chlorides, Synthetic materials, Aqueous solutions, Silica, Alkoxides, Polymers, Crystallization, Crystal growth, Hydrolysis, Nucleation
Citation
Li, J., Cookson, D. J., & Gerson, A. R. (2008). Crystal growth through progressive densification identified by synchrotron small-angle x-ray scattering. Crystal Growth & Design, 8(5), 1730-1733. doi:10.1021%2Fcg700788n