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Issue 13, 2009
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Combination of (100), (110) and (111) facets in MgO crystals shapes from dry to wet environment

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Abstract

At the onset of dissolution in water, cubic MgO smoke crystals present (110) cuts of the edges of the cubes. Next, (111) facets progressively dominate the shape of the crystallites, which finally transform into truncated octahedra. The morphology of the crystallites that are derived from surface energies computed within the density functional theory (DFT), only involve (100) and (111) facets. We explain the unexpected (110) cuts via a “constrained” Wulff equilibrium shape that arises from a slower kinetics of formation of (111) facets than (110) ones. Experiment and theory fully agree on the hierarchy of hydroxylated surface energies: Γ(111) < Γ(100) < Γ(110), both supporting the partial dissociation of water on MgO(100). Finally, from low to high PH2O (high to low T), DFT-based calculations predict a switch from Wulff shapes involving dry (100) facets, in which the (100)/(111) area ratio decreases upon increasing PH2O, to shapes involving hydroxylated (100) surfaces, in which the above ratio increases with PH2O.

Graphical abstract: Combination of (100), (110) and (111) facets in MgO crystals shapes from dry to wet environment

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Publication details

The article was received on 21 Jul 2008, accepted on 27 Nov 2008 and first published on 15 Jan 2009


Article type: Paper
DOI: 10.1039/B812376D
Citation: Phys. Chem. Chem. Phys., 2009,11, 2228-2233
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    Combination of (100), (110) and (111) facets in MgO crystals shapes from dry to wet environment

    P. Geysermans, F. Finocchi, J. Goniakowski, R. Hacquart and J. Jupille, Phys. Chem. Chem. Phys., 2009, 11, 2228
    DOI: 10.1039/B812376D

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