Biblioteca de la Universidad Complutense de Madrid

The effect of barium on calcite {101¯4} surfaces during growth

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Astilleros García-Monge, José Manuel y Pina Martínez, Carlos Manuel y Fernández Díaz, Lourdes y Putnis, Andrew (2000) The effect of barium on calcite {101¯4} surfaces during growth. Geochimica et cosmochimica acta, 64 (17). pp. 2965-2972. ISSN 0016-7037

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URL Oficial: http://www.journals.elsevier.com/geochimica-et-cosmochimica-acta/



Resumen

In situ atomic force microscopy (AFM) experiments have provided information about the effect of Ba21 on crystal growth of calcite {101¯4} surfaces. The microtopographic features observed have been interpreted by considering both the structural control that the calcite surfaces exert on the incorporation of divalent cations and the supersaturation state of the solution used. Pinning of the calcite growth steps occurs at low Ba concentrations, suggesting specific sites for Ba incorporation. When the Ba content of the solution is increased the advancement of monomolecular steps is observed. Although [4¯41]1 and [481¯]1 steps advance showing characteristic jagged edges, the parallel steps (i.e., [4¯41]2 and [481¯]2) remain practically immobile. This fact can be explained by considering the nonsymmetrically related distribution of large and small sites along the calcite steps and the easier incorporation of barium on the former. The measured increase in the height of the newly grown steps is also consistent with such preferential incorporation of Ba in certain positions. A further increase in the Ba concentration of the solutions leads to the formation of bidimensional nuclei on the calcite {101¯4} surfaces. The nature of these nuclei is discussed taking into account the supersaturation of the solution with respect to two possible structures that can accommodate Ba: the calcite-type structure and the aragonite-type structure.


Tipo de documento:Artículo
Palabras clave:Crystal growth; Calcite; Barium
Materias:Ciencias > Geología > Cristalografía
Código ID:14533
Depositado:07 Feb 2012 12:56
Última Modificación:24 Sep 2015 06:50

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