A Model To Compute Phase Diagrams In Oxides With Empirical Or First-Principles Energy Methods And Application To The Solubility Limits In The Cao-Mgo System

The CaO-MgO system is currently used as a prototype system to evaluate the accuracy of several energy and entropy approximations for predicting solid-state phase diagrams in ionic materials. Configurational disorder between the cations is parameterized with the cluster expansion technique. The vibrational contribution to the free energy is incorporated with a harmonic model that accounts for the dependence of the vibrational density of states on the cation configuration. The CaO-MgO phase diagram can be predicted very accurately with quantum mechanical energy methods, without the use of any adjustable parameters.