(10.4) Face of Ordered and Disordered Dolomite, MgCa(CO3)2: A Computational Study to Reveal the Growth Mechanism
by
Marco Bruno 1,*
and Erica Bittarello 2
Marco Bruno 1,* and Erica Bittarello 2
1
Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, 10125 Torino, Italy
2
Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, 10125 Torino, Italy
*
Author to whom correspondence should be addressed.
Minerals 2018, 8(8), 323; https://doi.org/10.3390/min8080323
Received: 6 July 2018 / Revised: 19 July 2018 / Accepted: 27 July 2018 / Published: 27 July 2018
(This article belongs to the Special Issue Computational Methods in Mineralogy and Geochemistry)
In this study, the stability of the (10.4) face of dolomite was systematically investigated. The surface energies at 0 K of the different (10.4) surfaces resulting from the cut of both ordered and disordered bulk structures were determined and compared, to establish how different atomic configurations (surface terminations) can affect the stability of the investigated face. To study the thermodynamic behavior of a surface, a 2D periodic slab model and the ab initio CRYSTAL code were adopted. The surface energies of the (10.4) faces of calcite and magnesite were also calculated in order to compare them with those of the different terminations of the (10.4) face of dolomite. Our calculations showed that the bulk of the dolomite crystal must have an ordered structure to reach the minimum of the energy, whereas the (10.4) surface is more stable when its structure is disordered. A growth model of the (10.4) face has been proposed: the peculiarity of this model consists in the existence of some disordered layers forming at the interface crystal/solution, which arrange in an ordered structure once covered by others disordered layers resulting by the spiral steps propagation.
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Keywords:
dolomite; surfaces; surface energy; quantum-mechanical calculations; disorder
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MDPI and ACS Style
Bruno, M.; Bittarello, E. (10.4) Face of Ordered and Disordered Dolomite, MgCa(CO3)2: A Computational Study to Reveal the Growth Mechanism. Minerals 2018, 8, 323.
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