Molecular dynamics investigation of MgO–CaO–SiO2 liquids: Influence of pressure and composition on density and transport properties

• Published in: Chemical geology Vol. 275; no. 1-2; pp. 50 - 57
• Main Authors: Zhang, Liqun, Van Orman, James A, Lacks, Daniel J
• Format: Journal Article
• Language: English
• Published: 01.07.2010
• Subjects: Density; Diffusivity; Dynamical systems; Liquids; Low pressure; Molecular dynamics; Silicon dioxide; Simulation; Transport properties
• ISSN: 0009-2541
• DOI: 10.1016/j.chemgeo.2010.04.012

Molecular dynamics simulations are carried out to address the influence of pressure and composition on the properties of liquids in the MgO-CaO-SiO2 system. At low pressure the mixing of liquids with different SiO2 fractions is highly non-ideal, while mixing of liquids with the same SiO2 fraction is nearly ideal; at high pressure, mixing becomes ideal for all systems. At low pressure, the viscosity and diffusivity of network forming ions, and their activation volumes, can change dramatically with changes in the SiO2 fraction of the liquid; at high pressure, the dependence of these properties on composition is relatively small, and the Ca/Mg ratio has an influence comparable to the SiO2 fraction. In general, the properties of the MgO-CaO-SiO2 system become much simpler at high pressure -- in contrast to the situation at low pressure, at high pressure mixing is ideal, the transport properties are relatively insensitive to composition, and there are no anomalous property changes with pressure.