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.