Thermodynamic modelling of the B-Ca, B-Sr and B-Ba systems

The boron-alkaline earth metal binary systems B-Ca, B-Sr and B-Ba have been modelled by means of the calculation of phase diagram (CALPHAD) technique, wherein the thermodynamic properties of the alkaline-earth hexaborides CaB6, SrB6, BaB6, and the elements α-B, β-B, fcc-Ca, fcc-Sr and bcc-Ba are obtained on the basis of the previous first-principles quasiharmonic phonon calculations. The temperature-composition (T-x) phase diagrams under different pressures are calculated for the aforementioned systems. These results provide helpful insights into appropriate processing conditions for guiding better fabrications of bulks and thin films of the alkaline-earth hexaborides. The present work indicates that the lower the pressures, the more favoured growth of thin films of the alkaline-earth hexaborides.