Static lattice energy calculations of mixing and ordering enthalpy in binary carbonate solid solutions

Enthalpies of mixing and ordering in the binaries of the quaternary carbonate (Ca,Mg,Fe,Mn)CO3 solid solution have been modeled using static lattice energy minimization calculations. A set of self-consistent empirical potentials has been specially developed for this task. The calculations illustrate the importance of size mismatch in determining magnitudes of the enthalpies of mixing and ordering in the binaries. The enthalpy effects show positive correlation with the predicted temperatures of the order/disorder transitions in intermediate compounds with the dolomite structure. It is shown that the general behavior of the mixing enthalpy in high- and low-T limits can be constrained with a minimum set of sampled configurations.