Computational study on thermodynamics of mixing and phase behaviour for CoO/FeO and CoO/MnO solid solutions

In this paper, a modified Monte Carlo technique, referred to as Monte Carlo exchange (MCX), is used to investigate the thermodynamic properties of CoO/FeO and CoO/MnO solid solutions. From MCX simulations the phase behaviour of CoO/FeO and CoO/MnO systems can be studied. The results show that these two systems exhibit a high degree of linear dependence of unit cell volume on composition. The calculated enthalpy of mixing shows very near-ideal behaviour at all compositions for CoO/FeO, but it predicts small positive deviation for CoO/MnO. The CoO/FeO solid solutions are completely miscible and form a single phase at all compositions (300, 1000, and 2000 K). The CoO/MnO solid solutions form two-phase region at 300 K but at high-temperatures (1000 and 2000 K) they are completely miscible and form a single phase at all compositions.