Thermochemistry of strontium incorporation in aragonite from atomistic simulations

We have investigated the thermodynamics of mixing between aragonite (orthorhombic CaCO3) and strontianite (SrCO3). In agreement with experiment, our simulations predict that there is a miscibility gap between the two solids at ambient conditions. All SrxCa1 xCO3 solids with compositions 0.12 < x < 0.87 are metastable with respect to separation into a Ca-rich and a Sr-rich phase. The concentration of Sr in coral aragonites (x 0.01) lies in the miscibility region of the phase diagram, and therefore formation of separated Sr-rich phases in coral aragonites is not thermodynamically favorable. The miscibility gap disappears at around 380 K. The enthalpy of mixing, which is positive and nearly symmetric with respect to x = 0.5, is the dominant contribution to the excess free energy, while the vibrational and configurational entropic contributions are small and of opposite sign. We provide a detailed comparison of our simulation results with available experimental data. Se investigó la actividad termodinámica existente entre la mezcla de la aragonita y el estroncio. Se ofrecen todos los datos experimentales y los resultados de la simulación efectuada predicen que hay un vacío en condiciones de ambiente.

Bibliographic Details

Main Authors:	Grau-Crespo, R., Ruiz-Hernández, S. E., Ruiz-Salvador, A. R., De Leeuw, N. H.
Format:	Journal Contribution biblioteca
Language:	English
Published:	Elsevier 2010
Subjects:	Strontium, Aragonite, Coral reefs, Thermodynamic activity,
Online Access:	http://hdl.handle.net/1834/4103
Tags:	Add Tag No Tags, Be the first to tag this record!