Phase equilibria modeling in Bi2O3–SrO–MnOx system

The selected pseudobinary, isothermal and isoactivity sections of the Bi2O3–SrO–MnOx phase diagram are constructed from the calculated phase equilibria. The starting point for the thermodynamic analysis were the assessments of the respective pseudobinary systems Bi2O3–SrO, Bi2O3–MnOx and SrO–MnOx. The only quaternary solid phase–the perovskite solid solution–is described in terms of the point defect model [ Bi3+1−xSr2+x] [ Mn3+1−x+2δ Mn4+x−2δ] [O2−1−δ/3 V aδ/3]3. The quaternary liquid is approximated by a phenomenological model using the liquid species Mn, MnO, MnO1.5, SrO, and BiO1.5 with only binary Redlich–Kister coefficients. The ab initio electronic structure calculations of cohesive energies are employed to evaluate the enthalpies of formation of some stoichiometric phases.