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The impact of nanocrystallite size and shape on phase transformation: Application to the boehmite/alumina transformation

Karouia, Fouad and Boualleg, Malika and Digne, Mathieu and Alphonse, Pierre The impact of nanocrystallite size and shape on phase transformation: Application to the boehmite/alumina transformation. (2016) Advanced Powder Technology, 27 (4). 1814-1820. ISSN 0921-8831

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Official URL: http://dx.doi.org/10.1016/j.apt.2016.06.014

Abstract

The thermal activation of oxyhydroxides is a key industrial process in preparing oxide materials. When dealing with nanoparticles, the phase transition properties are drastically modified. By preparing size- and shape-controlled boehmite nanoparticles, we demonstrate that the transformation temperature into γ-alumina is significantly altered. Rhombus crystallites were obtained from boehmite precipitated at basic pH, whereas crystallites precipitated at pH 4.5 were hexagonal. For the same crystallite size (ca. 4.5 nm), the transition temperature of the hexagonal crystallites was 315 °C whereas that of the rhombus ones was only 270 °C. A thermodynamic model was developed to rationalize these observations: the transition temperature results from a compromise between the crystallite size and the ratio of the lateral and basal surfaces. Consequently, the as-determined kinetic data could be a powerful tool for developing new efficient calcination processes and optimizing alumina properties.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at http://www.sciencedirect.com/science/article/pii/S0921883116301492
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
French research institutions > IFP Energies Nouvelles - IFPEN (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: cirimat webmestre
Deposited On:02 Feb 2017 14:16

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