Calculations of fluid-ternary solid solution equilibria: An application of the Wilson equation to fluid-(Fe, Mn, Mg)TiO3 equilibria at 600 °C and 1 kbar

Abstract

The Wilson equation (Wilson 1964) is applied to (Fe,Mn,Mg)TiO3 solid solutions for obtaining the mixing properties of the ternary solid solution at 600 °C and 1 kbar. The present study utilizes data on cation exchange between (Fe,Mn)Cl(2(aq)) and (Fe,Mn)TiO3, between (Mn,Mg)Cl(2(aq)) and (Mn,Mg)TiO3, and between (Fe,Mg)Cl(2(aq)) and (Fe,Mg)TiO3 (Kubo et al. 1992). The molar excess Gibbs energy (G(ex)) is the following: G(ex) (kJ/mol) =-7.260[X(FeTiO(3))ln(X(FeTiO(3)) + 1.314X(MnTiO(3)) + 0.962X(MgTiO(3))) + X(MnTiO(3))1n(0.585X(FeTiO(3)) + X(MnTiO(3)) + 0.393X(MgTiO(3))) + X(MgTiO(3))1n(0.406X(FeTiO(3)) + 0.371X(MnTiO(3)) + X(MgTiO(3)))], where X stands for the mole fraction of the subscripted component. The predicted compositions of (Fe,Mn,Mg)Cl(2(aq)) fluids in equilibrium with the ternary solid solutions are in good agreement with the experimental values.